text: /*global self*/
  /*jshint latedef: nofunc*/
  /*
  Distributed under both the W3C Test Suite License [1] and the W3C
  3-clause BSD License [2]. To contribute to a W3C Test Suite, see the
  policies and contribution forms [3].
  
  [1] http://www.w3.org/Consortium/Legal/2008/04-testsuite-license
  [2] http://www.w3.org/Consortium/Legal/2008/03-bsd-license
  [3] http://www.w3.org/2004/10/27-testcases
  */
  
  /* Documentation: https://web-platform-tests.org/writing-tests/testharness-api.html
   * (../docs/_writing-tests/testharness-api.md) */
  
  (function (global_scope)
  {
      var debug = false;
      // default timeout is 10 seconds, test can override if needed
      var settings = {
          output:true,
          harness_timeout:{
              "normal":10000,
              "long":60000
          },
          test_timeout:null,
          message_events: ["start", "test_state", "result", "completion"]
      };
  
      var xhtml_ns = "http://www.w3.org/1999/xhtml";
  
      /*
       * TestEnvironment is an abstraction for the environment in which the test
       * harness is used. Each implementation of a test environment has to provide
       * the following interface:
       *
       * interface TestEnvironment {
       *   // Invoked after the global 'tests' object has been created and it's
       *   // safe to call add_*_callback() to register event handlers.
       *   void on_tests_ready();
       *
       *   // Invoked after setup() has been called to notify the test environment
       *   // of changes to the test harness properties.
       *   void on_new_harness_properties(object properties);
       *
       *   // Should return a new unique default test name.
       *   DOMString next_default_test_name();
       *
       *   // Should return the test harness timeout duration in milliseconds.
       *   float test_timeout();
       * };
       */
  
      /*
       * A test environment with a DOM. The global object is 'window'. By default
       * test results are displayed in a table. Any parent windows receive
       * callbacks or messages via postMessage() when test events occur. See
       * apisample11.html and apisample12.html.
       */
      function WindowTestEnvironment() {
          this.name_counter = 0;
          this.window_cache = null;
          this.output_handler = null;
          this.all_loaded = false;
          var this_obj = this;
          this.message_events = [];
          this.dispatched_messages = [];
  
          this.message_functions = {
              start: [add_start_callback, remove_start_callback,
                      function (properties) {
                          this_obj._dispatch("start_callback", [properties],
                                             {type: "start", properties: properties});
                      }],
  
              test_state: [add_test_state_callback, remove_test_state_callback,
                           function(test) {
                               this_obj._dispatch("test_state_callback", [test],
                                                  {type: "test_state",
                                                   test: test.structured_clone()});
                           }],
              result: [add_result_callback, remove_result_callback,
                       function (test) {
                           this_obj.output_handler.show_status();
                           this_obj._dispatch("result_callback", [test],
                                              {type: "result",
                                               test: test.structured_clone()});
                       }],
              completion: [add_completion_callback, remove_completion_callback,
                           function (tests, harness_status) {
                               var cloned_tests = map(tests, function(test) {
                                   return test.structured_clone();
                               });
                               this_obj._dispatch("completion_callback", [tests, harness_status],
                                                  {type: "complete",
                                                   tests: cloned_tests,
                                                   status: harness_status.structured_clone()});
                           }]
          }
  
          on_event(window, 'load', function() {
              this_obj.all_loaded = true;
          });
  
          on_event(window, 'message', function(event) {
              if (event.data && event.data.type === "getmessages" && event.source) {
                  // A window can post "getmessages" to receive a duplicate of every
                  // message posted by this environment so far. This allows subscribers
                  // from fetch_tests_from_window to 'catch up' to the current state of
                  // this environment.
                  for (var i = 0; i < this_obj.dispatched_messages.length; ++i)
                  {
                      event.source.postMessage(this_obj.dispatched_messages[i], "*");
                  }
              }
          });
      }
  
      WindowTestEnvironment.prototype._dispatch = function(selector, callback_args, message_arg) {
          this.dispatched_messages.push(message_arg);
          this._forEach_windows(
                  function(w, same_origin) {
                      if (same_origin) {
                          try {
                              var has_selector = selector in w;
                          } catch(e) {
                              // If document.domain was set at some point same_origin can be
                              // wrong and the above will fail.
                              has_selector = false;
                          }
                          if (has_selector) {
                              try {
                                  w[selector].apply(undefined, callback_args);
                              } catch (e) {
                                  if (debug) {
                                      throw e;
                                  }
                              }
                          }
                      }
                      if (supports_post_message(w) && w !== self) {
                          w.postMessage(message_arg, "*");
                      }
                  });
      };
  
      WindowTestEnvironment.prototype._forEach_windows = function(callback) {
          // Iterate over the windows [self ... top, opener]. The callback is passed
          // two objects, the first one is the window object itself, the second one
          // is a boolean indicating whether or not it's on the same origin as the
          // current window.
          var cache = this.window_cache;
          if (!cache) {
              cache = [[self, true]];
              var w = self;
              var i = 0;
              var so;
              while (w != w.parent) {
                  w = w.parent;
                  so = is_same_origin(w);
                  cache.push([w, so]);
                  i++;
              }
              w = window.opener;
              if (w) {
                  cache.push([w, is_same_origin(w)]);
              }
              this.window_cache = cache;
          }
  
          forEach(cache,
                  function(a) {
                      callback.apply(null, a);
                  });
      };
  
      WindowTestEnvironment.prototype.on_tests_ready = function() {
          var output = new Output();
          this.output_handler = output;
  
          var this_obj = this;
  
          add_start_callback(function (properties) {
              this_obj.output_handler.init(properties);
          });
  
          add_test_state_callback(function(test) {
              this_obj.output_handler.show_status();
          });
  
          add_result_callback(function (test) {
              this_obj.output_handler.show_status();
          });
  
          add_completion_callback(function (tests, harness_status) {
              this_obj.output_handler.show_results(tests, harness_status);
          });
          this.setup_messages(settings.message_events);
      };
  
      WindowTestEnvironment.prototype.setup_messages = function(new_events) {
          var this_obj = this;
          forEach(settings.message_events, function(x) {
              var current_dispatch = this_obj.message_events.indexOf(x) !== -1;
              var new_dispatch = new_events.indexOf(x) !== -1;
              if (!current_dispatch && new_dispatch) {
                  this_obj.message_functions[x][0](this_obj.message_functions[x][2]);
              } else if (current_dispatch && !new_dispatch) {
                  this_obj.message_functions[x][1](this_obj.message_functions[x][2]);
              }
          });
          this.message_events = new_events;
      }
  
      WindowTestEnvironment.prototype.next_default_test_name = function() {
          var suffix = this.name_counter > 0 ? " " + this.name_counter : "";
          this.name_counter++;
          return get_title() + suffix;
      };
  
      WindowTestEnvironment.prototype.on_new_harness_properties = function(properties) {
          this.output_handler.setup(properties);
          if (properties.hasOwnProperty("message_events")) {
              this.setup_messages(properties.message_events);
          }
      };
  
      WindowTestEnvironment.prototype.add_on_loaded_callback = function(callback) {
          on_event(window, 'load', callback);
      };
  
      WindowTestEnvironment.prototype.test_timeout = function() {
          var metas = document.getElementsByTagName("meta");
          for (var i = 0; i < metas.length; i++) {
              if (metas[i].name == "timeout") {
                  if (metas[i].content == "long") {
                      return settings.harness_timeout.long;
                  }
                  break;
              }
          }
          return settings.harness_timeout.normal;
      };
  
      /*
       * Base TestEnvironment implementation for a generic web worker.
       *
       * Workers accumulate test results. One or more clients can connect and
       * retrieve results from a worker at any time.
       *
       * WorkerTestEnvironment supports communicating with a client via a
       * MessagePort.  The mechanism for determining the appropriate MessagePort
       * for communicating with a client depends on the type of worker and is
       * implemented by the various specializations of WorkerTestEnvironment
       * below.
       *
       * A client document using testharness can use fetch_tests_from_worker() to
       * retrieve results from a worker. See apisample16.html.
       */
      function WorkerTestEnvironment() {
          this.name_counter = 0;
          this.all_loaded = true;
          this.message_list = [];
          this.message_ports = [];
      }
  
      WorkerTestEnvironment.prototype._dispatch = function(message) {
          this.message_list.push(message);
          for (var i = 0; i < this.message_ports.length; ++i)
          {
              this.message_ports[i].postMessage(message);
          }
      };
  
      // The only requirement is that port has a postMessage() method. It doesn't
      // have to be an instance of a MessagePort, and often isn't.
      WorkerTestEnvironment.prototype._add_message_port = function(port) {
          this.message_ports.push(port);
          for (var i = 0; i < this.message_list.length; ++i)
          {
              port.postMessage(this.message_list[i]);
          }
      };
  
      WorkerTestEnvironment.prototype.next_default_test_name = function() {
          var suffix = this.name_counter > 0 ? " " + this.name_counter : "";
          this.name_counter++;
          return get_title() + suffix;
      };
  
      WorkerTestEnvironment.prototype.on_new_harness_properties = function() {};
  
      WorkerTestEnvironment.prototype.on_tests_ready = function() {
          var this_obj = this;
          add_start_callback(
                  function(properties) {
                      this_obj._dispatch({
                          type: "start",
                          properties: properties,
                      });
                  });
          add_test_state_callback(
                  function(test) {
                      this_obj._dispatch({
                          type: "test_state",
                          test: test.structured_clone()
                      });
                  });
          add_result_callback(
                  function(test) {
                      this_obj._dispatch({
                          type: "result",
                          test: test.structured_clone()
                      });
                  });
          add_completion_callback(
                  function(tests, harness_status) {
                      this_obj._dispatch({
                          type: "complete",
                          tests: map(tests,
                              function(test) {
                                  return test.structured_clone();
                              }),
                          status: harness_status.structured_clone()
                      });
                  });
      };
  
      WorkerTestEnvironment.prototype.add_on_loaded_callback = function() {};
  
      WorkerTestEnvironment.prototype.test_timeout = function() {
          // Tests running in a worker don't have a default timeout. I.e. all
          // worker tests behave as if settings.explicit_timeout is true.
          return null;
      };
  
      /*
       * Dedicated web workers.
       * https://html.spec.whatwg.org/multipage/workers.html#dedicatedworkerglobalscope
       *
       * This class is used as the test_environment when testharness is running
       * inside a dedicated worker.
       */
      function DedicatedWorkerTestEnvironment() {
          WorkerTestEnvironment.call(this);
          // self is an instance of DedicatedWorkerGlobalScope which exposes
          // a postMessage() method for communicating via the message channel
          // established when the worker is created.
          this._add_message_port(self);
      }
      DedicatedWorkerTestEnvironment.prototype = Object.create(WorkerTestEnvironment.prototype);
  
      DedicatedWorkerTestEnvironment.prototype.on_tests_ready = function() {
          WorkerTestEnvironment.prototype.on_tests_ready.call(this);
          // In the absence of an onload notification, we a require dedicated
          // workers to explicitly signal when the tests are done.
          tests.wait_for_finish = true;
      };
  
      /*
       * Shared web workers.
       * https://html.spec.whatwg.org/multipage/workers.html#sharedworkerglobalscope
       *
       * This class is used as the test_environment when testharness is running
       * inside a shared web worker.
       */
      function SharedWorkerTestEnvironment() {
          WorkerTestEnvironment.call(this);
          var this_obj = this;
          // Shared workers receive message ports via the 'onconnect' event for
          // each connection.
          self.addEventListener("connect",
                  function(message_event) {
                      this_obj._add_message_port(message_event.source);
                  }, false);
      }
      SharedWorkerTestEnvironment.prototype = Object.create(WorkerTestEnvironment.prototype);
  
      SharedWorkerTestEnvironment.prototype.on_tests_ready = function() {
          WorkerTestEnvironment.prototype.on_tests_ready.call(this);
          // In the absence of an onload notification, we a require shared
          // workers to explicitly signal when the tests are done.
          tests.wait_for_finish = true;
      };
  
      /*
       * Service workers.
       * http://www.w3.org/TR/service-workers/
       *
       * This class is used as the test_environment when testharness is running
       * inside a service worker.
       */
      function ServiceWorkerTestEnvironment() {
          WorkerTestEnvironment.call(this);
          this.all_loaded = false;
          this.on_loaded_callback = null;
          var this_obj = this;
          self.addEventListener("message",
                  function(event) {
                      if (event.data && event.data.type && event.data.type === "connect") {
                          if (event.ports && event.ports[0]) {
                              // If a MessageChannel was passed, then use it to
                              // send results back to the main window.  This
                              // allows the tests to work even if the browser
                              // does not fully support MessageEvent.source in
                              // ServiceWorkers yet.
                              this_obj._add_message_port(event.ports[0]);
                              event.ports[0].start();
                          } else {
                              // If there is no MessageChannel, then attempt to
                              // use the MessageEvent.source to send results
                              // back to the main window.
                              this_obj._add_message_port(event.source);
                          }
                      }
                  }, false);
  
          // The oninstall event is received after the service worker script and
          // all imported scripts have been fetched and executed. It's the
          // equivalent of an onload event for a document. All tests should have
          // been added by the time this event is received, thus it's not
          // necessary to wait until the onactivate event. However, tests for
          // installed service workers need another event which is equivalent to
          // the onload event because oninstall is fired only on installation. The
          // onmessage event is used for that purpose since tests using
          // testharness.js should ask the result to its service worker by
          // PostMessage. If the onmessage event is triggered on the service
          // worker's context, that means the worker's script has been evaluated.
          on_event(self, "install", on_all_loaded);
          on_event(self, "message", on_all_loaded);
          function on_all_loaded() {
              if (this_obj.all_loaded)
                  return;
              this_obj.all_loaded = true;
              if (this_obj.on_loaded_callback) {
                this_obj.on_loaded_callback();
              }
          }
      }
  
      ServiceWorkerTestEnvironment.prototype = Object.create(WorkerTestEnvironment.prototype);
  
      ServiceWorkerTestEnvironment.prototype.add_on_loaded_callback = function(callback) {
          if (this.all_loaded) {
              callback();
          } else {
              this.on_loaded_callback = callback;
          }
      };
  
      /*
       * JavaScript shells.
       *
       * This class is used as the test_environment when testharness is running
       * inside a JavaScript shell.
       */
      function ShellTestEnvironment() {
          this.name_counter = 0;
          this.all_loaded = false;
          this.on_loaded_callback = null;
          Promise.resolve().then(function() {
              this.all_loaded = true
              if (this.on_loaded_callback) {
                  this.on_loaded_callback();
              }
          }.bind(this));
          this.message_list = [];
          this.message_ports = [];
      }
  
      ShellTestEnvironment.prototype.next_default_test_name = function() {
          var suffix = this.name_counter > 0 ? " " + this.name_counter : "";
          this.name_counter++;
          return "Untitled" + suffix;
      };
  
      ShellTestEnvironment.prototype.on_new_harness_properties = function() {};
  
      ShellTestEnvironment.prototype.on_tests_ready = function() {};
  
      ShellTestEnvironment.prototype.add_on_loaded_callback = function(callback) {
          if (this.all_loaded) {
              callback();
          } else {
              this.on_loaded_callback = callback;
          }
      };
  
      ShellTestEnvironment.prototype.test_timeout = function() {
          // Tests running in a shell don't have a default timeout, so behave as
          // if settings.explicit_timeout is true.
          return null;
      };
  
      function create_test_environment() {
          if ('document' in global_scope) {
              return new WindowTestEnvironment();
          }
          if ('DedicatedWorkerGlobalScope' in global_scope &&
              global_scope instanceof DedicatedWorkerGlobalScope) {
              return new DedicatedWorkerTestEnvironment();
          }
          if ('SharedWorkerGlobalScope' in global_scope &&
              global_scope instanceof SharedWorkerGlobalScope) {
              return new SharedWorkerTestEnvironment();
          }
          if ('ServiceWorkerGlobalScope' in global_scope &&
              global_scope instanceof ServiceWorkerGlobalScope) {
              return new ServiceWorkerTestEnvironment();
          }
          if ('WorkerGlobalScope' in global_scope &&
              global_scope instanceof WorkerGlobalScope) {
              return new DedicatedWorkerTestEnvironment();
          }
  
          if (!('location' in global_scope)) {
              return new ShellTestEnvironment();
          }
  
          throw new Error("Unsupported test environment");
      }
  
      var test_environment = create_test_environment();
  
      function is_shared_worker(worker) {
          return 'SharedWorker' in global_scope && worker instanceof SharedWorker;
      }
  
      function is_service_worker(worker) {
          // The worker object may be from another execution context,
          // so do not use instanceof here.
          return 'ServiceWorker' in global_scope &&
              Object.prototype.toString.call(worker) == '[object ServiceWorker]';
      }
  
      /*
       * API functions
       */
      function test(func, name, properties)
      {
          var test_name = name ? name : test_environment.next_default_test_name();
          properties = properties ? properties : {};
          var test_obj = new Test(test_name, properties);
          var value = test_obj.step(func, test_obj, test_obj);
  
          if (value !== undefined) {
              var msg = "Test named \"" + test_name +
                  "\" inappropriately returned a value";
  
              try {
                  if (value && value.hasOwnProperty("then")) {
                      msg += ", consider using `promise_test` instead";
                  }
              } catch (err) {}
  
              tests.status.status = tests.status.ERROR;
              tests.status.message = msg;
          }
  
          if (test_obj.phase === test_obj.phases.STARTED) {
              test_obj.done();
          }
      }
  
      function async_test(func, name, properties)
      {
          if (typeof func !== "function") {
              properties = name;
              name = func;
              func = null;
          }
          var test_name = name ? name : test_environment.next_default_test_name();
          properties = properties ? properties : {};
          var test_obj = new Test(test_name, properties);
          if (func) {
              test_obj.step(func, test_obj, test_obj);
          }
          return test_obj;
      }
  
      function promise_test(func, name, properties) {
          var test = async_test(name, properties);
          test._is_promise_test = true;
  
          // If there is no promise tests queue make one.
          if (!tests.promise_tests) {
              tests.promise_tests = Promise.resolve();
          }
          tests.promise_tests = tests.promise_tests.then(function() {
              return new Promise(function(resolve) {
                  var promise = test.step(func, test, test);
  
                  test.step(function() {
                      assert(!!promise, "promise_test", null,
                             "test body must return a 'thenable' object (received ${value})",
                             {value:promise});
                      assert(typeof promise.then === "function", "promise_test", null,
                             "test body must return a 'thenable' object (received an object with no `then` method)",
                             null);
                  });
  
                  // Test authors may use the `step` method within a
                  // `promise_test` even though this reflects a mixture of
                  // asynchronous control flow paradigms. The "done" callback
                  // should be registered prior to the resolution of the
                  // user-provided Promise to avoid timeouts in cases where the
                  // Promise does not settle but a `step` function has thrown an
                  // error.
                  add_test_done_callback(test, resolve);
  
                  Promise.resolve(promise)
                      .catch(test.step_func(
                          function(value) {
                              if (value instanceof AssertionError) {
                                  throw value;
                              }
                              assert(false, "promise_test", null,
                                     "Unhandled rejection with value: ${value}", {value:value});
                          }))
                      .then(function() {
                          test.done();
                      });
                  });
          });
      }
  
      function promise_rejects(test, expected, promise, description) {
          return promise.then(test.unreached_func("Should have rejected: " + description)).catch(function(e) {
              assert_throws(expected, function() { throw e }, description);
          });
      }
  
      function promise_rejects_js(test, expected, promise, description) {
          return promise.then(test.unreached_func("Should have rejected: " + description)).catch(function(e) {
              assert_throws_js_impl(expected, function() { throw e },
                                    description, "promise_reject_js");
          });
      }
  
      function promise_rejects_dom(test, expected, promise, description) {
          return promise.then(test.unreached_func("Should have rejected: " + description)).catch(function(e) {
              assert_throws_dom_impl(expected, function() { throw e },
                                     description, "promise_rejects_dom");
          });
      }
  
      function promise_rejects_exactly(test, expected, promise, description) {
          return promise.then(test.unreached_func("Should have rejected: " + description)).catch(function(e) {
              assert_throws_exactly_impl(expected, function() { throw e },
                                         description, "promise_rejects_exactly");
          });
      }
  
      /**
       * This constructor helper allows DOM events to be handled using Promises,
       * which can make it a lot easier to test a very specific series of events,
       * including ensuring that unexpected events are not fired at any point.
       */
      function EventWatcher(test, watchedNode, eventTypes, timeoutPromise)
      {
          if (typeof eventTypes == 'string') {
              eventTypes = [eventTypes];
          }
  
          var waitingFor = null;
  
          // This is null unless we are recording all events, in which case it
          // will be an Array object.
          var recordedEvents = null;
  
          var eventHandler = test.step_func(function(evt) {
              assert_true(!!waitingFor,
                          'Not expecting event, but got ' + evt.type + ' event');
              assert_equals(evt.type, waitingFor.types[0],
                            'Expected ' + waitingFor.types[0] + ' event, but got ' +
                            evt.type + ' event instead');
  
              if (Array.isArray(recordedEvents)) {
                  recordedEvents.push(evt);
              }
  
              if (waitingFor.types.length > 1) {
                  // Pop first event from array
                  waitingFor.types.shift();
                  return;
              }
              // We need to null out waitingFor before calling the resolve function
              // since the Promise's resolve handlers may call wait_for() which will
              // need to set waitingFor.
              var resolveFunc = waitingFor.resolve;
              waitingFor = null;
              // Likewise, we should reset the state of recordedEvents.
              var result = recordedEvents || evt;
              recordedEvents = null;
              resolveFunc(result);
          });
  
          for (var i = 0; i < eventTypes.length; i++) {
              watchedNode.addEventListener(eventTypes[i], eventHandler, false);
          }
  
          /**
           * Returns a Promise that will resolve after the specified event or
           * series of events has occurred.
           *
           * @param options An optional options object. If the 'record' property
           *                on this object has the value 'all', when the Promise
           *                returned by this function is resolved,  *all* Event
           *                objects that were waited for will be returned as an
           *                array.
           *
           * For example,
           *
           * ```js
           * const watcher = new EventWatcher(t, div, [ 'animationstart',
           *                                            'animationiteration',
           *                                            'animationend' ]);
           * return watcher.wait_for([ 'animationstart', 'animationend' ],
           *                         { record: 'all' }).then(evts => {
           *   assert_equals(evts[0].elapsedTime, 0.0);
           *   assert_equals(evts[1].elapsedTime, 2.0);
           * });
           * ```
           */
          this.wait_for = function(types, options) {
              if (waitingFor) {
                  return Promise.reject('Already waiting for an event or events');
              }
              if (typeof types == 'string') {
                  types = [types];
              }
              if (options && options.record && options.record === 'all') {
                  recordedEvents = [];
              }
              return new Promise(function(resolve, reject) {
                  var timeout = test.step_func(function() {
                      // If the timeout fires after the events have been received
                      // or during a subsequent call to wait_for, ignore it.
                      if (!waitingFor || waitingFor.resolve !== resolve)
                          return;
  
                      // This should always fail, otherwise we should have
                      // resolved the promise.
                      assert_true(waitingFor.types.length == 0,
                                  'Timed out waiting for ' + waitingFor.types.join(', '));
                      var result = recordedEvents;
                      recordedEvents = null;
                      var resolveFunc = waitingFor.resolve;
                      waitingFor = null;
                      resolveFunc(result);
                  });
  
                  if (timeoutPromise) {
                      timeoutPromise().then(timeout);
                  }
  
                  waitingFor = {
                      types: types,
                      resolve: resolve,
                      reject: reject
                  };
              });
          };
  
          function stop_watching() {
              for (var i = 0; i < eventTypes.length; i++) {
                  watchedNode.removeEventListener(eventTypes[i], eventHandler, false);
              }
          };
  
          test._add_cleanup(stop_watching);
  
          return this;
      }
      expose(EventWatcher, 'EventWatcher');
  
      function setup(func_or_properties, maybe_properties)
      {
          var func = null;
          var properties = {};
          if (arguments.length === 2) {
              func = func_or_properties;
              properties = maybe_properties;
          } else if (func_or_properties instanceof Function) {
              func = func_or_properties;
          } else {
              properties = func_or_properties;
          }
          tests.setup(func, properties);
          test_environment.on_new_harness_properties(properties);
      }
  
      function done() {
          if (tests.tests.length === 0) {
              // `done` is invoked after handling uncaught exceptions, so if the
              // harness status is already set, the corresponding message is more
              // descriptive than the generic message defined here.
              if (tests.status.status === null) {
                  tests.status.status = tests.status.ERROR;
                  tests.status.message = "done() was called without first defining any tests";
              }
  
              tests.complete();
              return;
          }
          if (tests.file_is_test) {
              // file is test files never have asynchronous cleanup logic,
              // meaning the fully-synchronous `done` function can be used here.
              tests.tests[0].done();
          }
          tests.end_wait();
      }
  
      function generate_tests(func, args, properties) {
          forEach(args, function(x, i)
                  {
                      var name = x[0];
                      test(function()
                           {
                               func.apply(this, x.slice(1));
                           },
                           name,
                           Array.isArray(properties) ? properties[i] : properties);
                  });
      }
  
      /*
       * Register a function as a DOM event listener to the given object for the
       * event bubbling phase.
       *
       * This function was deprecated in November of 2019.
       */
      function on_event(object, event, callback)
      {
          object.addEventListener(event, callback, false);
      }
  
      function step_timeout(f, t) {
          var outer_this = this;
          var args = Array.prototype.slice.call(arguments, 2);
          return setTimeout(function() {
              f.apply(outer_this, args);
          }, t * tests.timeout_multiplier);
      }
  
      expose(test, 'test');
      expose(async_test, 'async_test');
      expose(promise_test, 'promise_test');
      expose(promise_rejects, 'promise_rejects');
      expose(promise_rejects_js, 'promise_rejects_js');
      expose(promise_rejects_dom, 'promise_rejects_dom');
      expose(promise_rejects_exactly, 'promise_rejects_exactly');
      expose(generate_tests, 'generate_tests');
      expose(setup, 'setup');
      expose(done, 'done');
      expose(on_event, 'on_event');
      expose(step_timeout, 'step_timeout');
  
      /*
       * Return a string truncated to the given length, with ... added at the end
       * if it was longer.
       */
      function truncate(s, len)
      {
          if (s.length > len) {
              return s.substring(0, len - 3) + "...";
          }
          return s;
      }
  
      /*
       * Return true if object is probably a Node object.
       */
      function is_node(object)
      {
          // I use duck-typing instead of instanceof, because
          // instanceof doesn't work if the node is from another window (like an
          // iframe's contentWindow):
          // http://www.w3.org/Bugs/Public/show_bug.cgi?id=12295
          try {
              var has_node_properties = ("nodeType" in object &&
                                         "nodeName" in object &&
                                         "nodeValue" in object &&
                                         "childNodes" in object);
          } catch (e) {
              // We're probably cross-origin, which means we aren't a node
              return false;
          }
  
          if (has_node_properties) {
              try {
                  object.nodeType;
              } catch (e) {
                  // The object is probably Node.prototype or another prototype
                  // object that inherits from it, and not a Node instance.
                  return false;
              }
              return true;
          }
          return false;
      }
  
      var replacements = {
          "0": "0",
          "1": "x01",
          "2": "x02",
          "3": "x03",
          "4": "x04",
          "5": "x05",
          "6": "x06",
          "7": "x07",
          "8": "b",
          "9": "t",
          "10": "n",
          "11": "v",
          "12": "f",
          "13": "r",
          "14": "x0e",
          "15": "x0f",
          "16": "x10",
          "17": "x11",
          "18": "x12",
          "19": "x13",
          "20": "x14",
          "21": "x15",
          "22": "x16",
          "23": "x17",
          "24": "x18",
          "25": "x19",
          "26": "x1a",
          "27": "x1b",
          "28": "x1c",
          "29": "x1d",
          "30": "x1e",
          "31": "x1f",
          "0xfffd": "ufffd",
          "0xfffe": "ufffe",
          "0xffff": "uffff",
      };
  
      /*
       * Convert a value to a nice, human-readable string
       */
      function format_value(val, seen)
      {
          if (!seen) {
              seen = [];
          }
          if (typeof val === "object" && val !== null) {
              if (seen.indexOf(val) >= 0) {
                  return "[...]";
              }
              seen.push(val);
          }
          if (Array.isArray(val)) {
              return "[" + val.map(function(x) {return format_value(x, seen);}).join(", ") + "]";
          }
  
          switch (typeof val) {
          case "string":
              val = val.replace("\\", "\\\\");
              for (var p in replacements) {
                  var replace = "\\" + replacements[p];
                  val = val.replace(RegExp(String.fromCharCode(p), "g"), replace);
              }
              return '"' + val.replace(/"/g, '\\"') + '"';
          case "boolean":
          case "undefined":
              return String(val);
          case "number":
              // In JavaScript, -0 === 0 and String(-0) == "0", so we have to
              // special-case.
              if (val === -0 && 1/val === -Infinity) {
                  return "-0";
              }
              return String(val);
          case "object":
              if (val === null) {
                  return "null";
              }
  
              // Special-case Node objects, since those come up a lot in my tests.  I
              // ignore namespaces.
              if (is_node(val)) {
                  switch (val.nodeType) {
                  case Node.ELEMENT_NODE:
                      var ret = "<" + val.localName;
                      for (var i = 0; i < val.attributes.length; i++) {
                          ret += " " + val.attributes[i].name + '="' + val.attributes[i].value + '"';
                      }
                      ret += ">" + val.innerHTML + "</" + val.localName + ">";
                      return "Element node " + truncate(ret, 60);
                  case Node.TEXT_NODE:
                      return 'Text node "' + truncate(val.data, 60) + '"';
                  case Node.PROCESSING_INSTRUCTION_NODE:
                      return "ProcessingInstruction node with target " + format_value(truncate(val.target, 60)) + " and data " + format_value(truncate(val.data, 60));
                  case Node.COMMENT_NODE:
                      return "Comment node <!--" + truncate(val.data, 60) + "-->";
                  case Node.DOCUMENT_NODE:
                      return "Document node with " + val.childNodes.length + (val.childNodes.length == 1 ? " child" : " children");
                  case Node.DOCUMENT_TYPE_NODE:
                      return "DocumentType node";
                  case Node.DOCUMENT_FRAGMENT_NODE:
                      return "DocumentFragment node with " + val.childNodes.length + (val.childNodes.length == 1 ? " child" : " children");
                  default:
                      return "Node object of unknown type";
                  }
              }
  
          /* falls through */
          default:
              try {
                  return typeof val + ' "' + truncate(String(val), 1000) + '"';
              } catch(e) {
                  return ("[stringifying object threw " + String(e) +
                          " with type " + String(typeof e) + "]");
              }
          }
      }
      expose(format_value, "format_value");
  
      /*
       * Assertions
       */
  
      function assert_true(actual, description)
      {
          assert(actual === true, "assert_true", description,
                                  "expected true got ${actual}", {actual:actual});
      }
      expose(assert_true, "assert_true");
  
      function assert_false(actual, description)
      {
          assert(actual === false, "assert_false", description,
                                   "expected false got ${actual}", {actual:actual});
      }
      expose(assert_false, "assert_false");
  
      function same_value(x, y) {
          if (y !== y) {
              //NaN case
              return x !== x;
          }
          if (x === 0 && y === 0) {
              //Distinguish +0 and -0
              return 1/x === 1/y;
          }
          return x === y;
      }
  
      function assert_equals(actual, expected, description)
      {
           /*
            * Test if two primitives are equal or two objects
            * are the same object
            */
          if (typeof actual != typeof expected) {
              assert(false, "assert_equals", description,
                            "expected (" + typeof expected + ") ${expected} but got (" + typeof actual + ") ${actual}",
                            {expected:expected, actual:actual});
              return;
          }
          assert(same_value(actual, expected), "assert_equals", description,
                                               "expected ${expected} but got ${actual}",
                                               {expected:expected, actual:actual});
      }
      expose(assert_equals, "assert_equals");
  
      function assert_not_equals(actual, expected, description)
      {
           /*
            * Test if two primitives are unequal or two objects
            * are different objects
            */
          assert(!same_value(actual, expected), "assert_not_equals", description,
                                                "got disallowed value ${actual}",
                                                {actual:actual});
      }
      expose(assert_not_equals, "assert_not_equals");
  
      function assert_in_array(actual, expected, description)
      {
          assert(expected.indexOf(actual) != -1, "assert_in_array", description,
                                                 "value ${actual} not in array ${expected}",
                                                 {actual:actual, expected:expected});
      }
      expose(assert_in_array, "assert_in_array");
  
      function assert_object_equals(actual, expected, description)
      {
           assert(typeof actual === "object" && actual !== null, "assert_object_equals", description,
                                                                 "value is ${actual}, expected object",
                                                                 {actual: actual});
           //This needs to be improved a great deal
           function check_equal(actual, expected, stack)
           {
               stack.push(actual);
  
               var p;
               for (p in actual) {
                   assert(expected.hasOwnProperty(p), "assert_object_equals", description,
                                                      "unexpected property ${p}", {p:p});
  
                   if (typeof actual[p] === "object" && actual[p] !== null) {
                       if (stack.indexOf(actual[p]) === -1) {
                           check_equal(actual[p], expected[p], stack);
                       }
                   } else {
                       assert(same_value(actual[p], expected[p]), "assert_object_equals", description,
                                                         "property ${p} expected ${expected} got ${actual}",
                                                         {p:p, expected:expected, actual:actual});
                   }
               }
               for (p in expected) {
                   assert(actual.hasOwnProperty(p),
                          "assert_object_equals", description,
                          "expected property ${p} missing", {p:p});
               }
               stack.pop();
           }
           check_equal(actual, expected, []);
      }
      expose(assert_object_equals, "assert_object_equals");
  
      function assert_array_equals(actual, expected, description)
      {
          assert(typeof actual === "object" && actual !== null && "length" in actual,
                 "assert_array_equals", description,
                 "value is ${actual}, expected array",
                 {actual:actual});
          assert(actual.length === expected.length,
                 "assert_array_equals", description,
                 "lengths differ, expected ${expected} got ${actual}",
                 {expected:expected.length, actual:actual.length});
  
          for (var i = 0; i < actual.length; i++) {
              assert(actual.hasOwnProperty(i) === expected.hasOwnProperty(i),
                     "assert_array_equals", description,
                     "property ${i}, property expected to be ${expected} but was ${actual}",
                     {i:i, expected:expected.hasOwnProperty(i) ? "present" : "missing",
                     actual:actual.hasOwnProperty(i) ? "present" : "missing"});
              assert(same_value(expected[i], actual[i]),
                     "assert_array_equals", description,
                     "property ${i}, expected ${expected} but got ${actual}",
                     {i:i, expected:expected[i], actual:actual[i]});
          }
      }
      expose(assert_array_equals, "assert_array_equals");
  
      function assert_array_approx_equals(actual, expected, epsilon, description)
      {
          /*
           * Test if two primitive arrays are equal within +/- epsilon
           */
          assert(actual.length === expected.length,
                 "assert_array_approx_equals", description,
                 "lengths differ, expected ${expected} got ${actual}",
                 {expected:expected.length, actual:actual.length});
  
          for (var i = 0; i < actual.length; i++) {
              assert(actual.hasOwnProperty(i) === expected.hasOwnProperty(i),
                     "assert_array_approx_equals", description,
                     "property ${i}, property expected to be ${expected} but was ${actual}",
                     {i:i, expected:expected.hasOwnProperty(i) ? "present" : "missing",
                     actual:actual.hasOwnProperty(i) ? "present" : "missing"});
              assert(typeof actual[i] === "number",
                     "assert_array_approx_equals", description,
                     "property ${i}, expected a number but got a ${type_actual}",
                     {i:i, type_actual:typeof actual[i]});
              assert(Math.abs(actual[i] - expected[i]) <= epsilon,
                     "assert_array_approx_equals", description,
                     "property ${i}, expected ${expected} +/- ${epsilon}, expected ${expected} but got ${actual}",
                     {i:i, expected:expected[i], actual:actual[i], epsilon:epsilon});
          }
      }
      expose(assert_array_approx_equals, "assert_array_approx_equals");
  
      function assert_approx_equals(actual, expected, epsilon, description)
      {
          /*
           * Test if two primitive numbers are equal within +/- epsilon
           */
          assert(typeof actual === "number",
                 "assert_approx_equals", description,
                 "expected a number but got a ${type_actual}",
                 {type_actual:typeof actual});
  
          assert(Math.abs(actual - expected) <= epsilon,
                 "assert_approx_equals", description,
                 "expected ${expected} +/- ${epsilon} but got ${actual}",
                 {expected:expected, actual:actual, epsilon:epsilon});
      }
      expose(assert_approx_equals, "assert_approx_equals");
  
      function assert_less_than(actual, expected, description)
      {
          /*
           * Test if a primitive number is less than another
           */
          assert(typeof actual === "number",
                 "assert_less_than", description,
                 "expected a number but got a ${type_actual}",
                 {type_actual:typeof actual});
  
          assert(actual < expected,
                 "assert_less_than", description,
                 "expected a number less than ${expected} but got ${actual}",
                 {expected:expected, actual:actual});
      }
      expose(assert_less_than, "assert_less_than");
  
      function assert_greater_than(actual, expected, description)
      {
          /*
           * Test if a primitive number is greater than another
           */
          assert(typeof actual === "number",
                 "assert_greater_than", description,
                 "expected a number but got a ${type_actual}",
                 {type_actual:typeof actual});
  
          assert(actual > expected,
                 "assert_greater_than", description,
                 "expected a number greater than ${expected} but got ${actual}",
                 {expected:expected, actual:actual});
      }
      expose(assert_greater_than, "assert_greater_than");
  
      function assert_between_exclusive(actual, lower, upper, description)
      {
          /*
           * Test if a primitive number is between two others
           */
          assert(typeof actual === "number",
                 "assert_between_exclusive", description,
                 "expected a number but got a ${type_actual}",
                 {type_actual:typeof actual});
  
          assert(actual > lower && actual < upper,
                 "assert_between_exclusive", description,
                 "expected a number greater than ${lower} " +
                 "and less than ${upper} but got ${actual}",
                 {lower:lower, upper:upper, actual:actual});
      }
      expose(assert_between_exclusive, "assert_between_exclusive");
  
      function assert_less_than_equal(actual, expected, description)
      {
          /*
           * Test if a primitive number is less than or equal to another
           */
          assert(typeof actual === "number",
                 "assert_less_than_equal", description,
                 "expected a number but got a ${type_actual}",
                 {type_actual:typeof actual});
  
          assert(actual <= expected,
                 "assert_less_than_equal", description,
                 "expected a number less than or equal to ${expected} but got ${actual}",
                 {expected:expected, actual:actual});
      }
      expose(assert_less_than_equal, "assert_less_than_equal");
  
      function assert_greater_than_equal(actual, expected, description)
      {
          /*
           * Test if a primitive number is greater than or equal to another
           */
          assert(typeof actual === "number",
                 "assert_greater_than_equal", description,
                 "expected a number but got a ${type_actual}",
                 {type_actual:typeof actual});
  
          assert(actual >= expected,
                 "assert_greater_than_equal", description,
                 "expected a number greater than or equal to ${expected} but got ${actual}",
                 {expected:expected, actual:actual});
      }
      expose(assert_greater_than_equal, "assert_greater_than_equal");
  
      function assert_between_inclusive(actual, lower, upper, description)
      {
          /*
           * Test if a primitive number is between to two others or equal to either of them
           */
          assert(typeof actual === "number",
                 "assert_between_inclusive", description,
                 "expected a number but got a ${type_actual}",
                 {type_actual:typeof actual});
  
          assert(actual >= lower && actual <= upper,
                 "assert_between_inclusive", description,
                 "expected a number greater than or equal to ${lower} " +
                 "and less than or equal to ${upper} but got ${actual}",
                 {lower:lower, upper:upper, actual:actual});
      }
      expose(assert_between_inclusive, "assert_between_inclusive");
  
      function assert_regexp_match(actual, expected, description) {
          /*
           * Test if a string (actual) matches a regexp (expected)
           */
          assert(expected.test(actual),
                 "assert_regexp_match", description,
                 "expected ${expected} but got ${actual}",
                 {expected:expected, actual:actual});
      }
      expose(assert_regexp_match, "assert_regexp_match");
  
      function assert_class_string(object, class_string, description) {
          var actual = {}.toString.call(object);
          var expected = "[object " + class_string + "]";
          assert(same_value(actual, expected), "assert_class_string", description,
                                               "expected ${expected} but got ${actual}",
                                               {expected:expected, actual:actual});
      }
      expose(assert_class_string, "assert_class_string");
  
  
      function assert_own_property(object, property_name, description) {
          assert(object.hasOwnProperty(property_name),
                 "assert_own_property", description,
                 "expected property ${p} missing", {p:property_name});
      }
      expose(assert_own_property, "assert_own_property");
  
      function assert_not_own_property(object, property_name, description) {
          assert(!object.hasOwnProperty(property_name),
                 "assert_not_own_property", description,
                 "unexpected property ${p} is found on object", {p:property_name});
      }
      expose(assert_not_own_property, "assert_not_own_property");
  
      function _assert_inherits(name) {
          return function (object, property_name, description)
          {
              assert(typeof object === "object" || typeof object === "function",
                     name, description,
                     "provided value is not an object");
  
              assert("hasOwnProperty" in object,
                     name, description,
                     "provided value is an object but has no hasOwnProperty method");
  
              assert(!object.hasOwnProperty(property_name),
                     name, description,
                     "property ${p} found on object expected in prototype chain",
                     {p:property_name});
  
              assert(property_name in object,
                     name, description,
                     "property ${p} not found in prototype chain",
                     {p:property_name});
          };
      }
      expose(_assert_inherits("assert_inherits"), "assert_inherits");
      expose(_assert_inherits("assert_idl_attribute"), "assert_idl_attribute");
  
      function assert_readonly(object, property_name, description)
      {
           var initial_value = object[property_name];
           try {
               //Note that this can have side effects in the case where
               //the property has PutForwards
               object[property_name] = initial_value + "a"; //XXX use some other value here?
               assert(same_value(object[property_name], initial_value),
                      "assert_readonly", description,
                      "changing property ${p} succeeded",
                      {p:property_name});
           } finally {
               object[property_name] = initial_value;
           }
      }
      expose(assert_readonly, "assert_readonly");
  
      /**
       * Assert an Exception with the expected code is thrown.
       *
       * @param {object|number|string} code The expected exception code.
       * @param {Function} func Function which should throw.
       * @param {string} description Error description for the case that the error is not thrown.
       */
      function assert_throws(code, func, description)
      {
          try {
              func.call(this);
              assert(false, "assert_throws", description,
                     "${func} did not throw", {func:func});
          } catch (e) {
              if (e instanceof AssertionError) {
                  throw e;
              }
  
              assert(typeof e === "object",
                     "assert_throws", description,
                     "${func} threw ${e} with type ${type}, not an object",
                     {func:func, e:e, type:typeof e});
  
              assert(e !== null,
                     "assert_throws", description,
                     "${func} threw null, not an object",
                     {func:func});
  
              if (code === null) {
                  throw new AssertionError('Test bug: need to pass exception to assert_throws()');
              }
              if (typeof code === "object") {
                  assert("name" in e && e.name == code.name,
                         "assert_throws", description,
                         "${func} threw ${actual} (${actual_name}) expected ${expected} (${expected_name})",
                                      {func:func, actual:e, actual_name:e.name,
                                       expected:code,
                                       expected_name:code.name});
                  return;
              }
  
              var code_name_map = {
                  INDEX_SIZE_ERR: 'IndexSizeError',
                  HIERARCHY_REQUEST_ERR: 'HierarchyRequestError',
                  WRONG_DOCUMENT_ERR: 'WrongDocumentError',
                  INVALID_CHARACTER_ERR: 'InvalidCharacterError',
                  NO_MODIFICATION_ALLOWED_ERR: 'NoModificationAllowedError',
                  NOT_FOUND_ERR: 'NotFoundError',
                  NOT_SUPPORTED_ERR: 'NotSupportedError',
                  INUSE_ATTRIBUTE_ERR: 'InUseAttributeError',
                  INVALID_STATE_ERR: 'InvalidStateError',
                  SYNTAX_ERR: 'SyntaxError',
                  INVALID_MODIFICATION_ERR: 'InvalidModificationError',
                  NAMESPACE_ERR: 'NamespaceError',
                  INVALID_ACCESS_ERR: 'InvalidAccessError',
                  TYPE_MISMATCH_ERR: 'TypeMismatchError',
                  SECURITY_ERR: 'SecurityError',
                  NETWORK_ERR: 'NetworkError',
                  ABORT_ERR: 'AbortError',
                  URL_MISMATCH_ERR: 'URLMismatchError',
                  QUOTA_EXCEEDED_ERR: 'QuotaExceededError',
                  TIMEOUT_ERR: 'TimeoutError',
                  INVALID_NODE_TYPE_ERR: 'InvalidNodeTypeError',
                  DATA_CLONE_ERR: 'DataCloneError'
              };
  
              var name = code in code_name_map ? code_name_map[code] : code;
  
              var name_code_map = {
                  IndexSizeError: 1,
                  HierarchyRequestError: 3,
                  WrongDocumentError: 4,
                  InvalidCharacterError: 5,
                  NoModificationAllowedError: 7,
                  NotFoundError: 8,
                  NotSupportedError: 9,
                  InUseAttributeError: 10,
                  InvalidStateError: 11,
                  SyntaxError: 12,
                  InvalidModificationError: 13,
                  NamespaceError: 14,
                  InvalidAccessError: 15,
                  TypeMismatchError: 17,
                  SecurityError: 18,
                  NetworkError: 19,
                  AbortError: 20,
                  URLMismatchError: 21,
                  QuotaExceededError: 22,
                  TimeoutError: 23,
                  InvalidNodeTypeError: 24,
                  DataCloneError: 25,
  
                  EncodingError: 0,
                  NotReadableError: 0,
                  UnknownError: 0,
                  ConstraintError: 0,
                  DataError: 0,
                  TransactionInactiveError: 0,
                  ReadOnlyError: 0,
                  VersionError: 0,
                  OperationError: 0,
                  NotAllowedError: 0
              };
  
              var code_name_map = {};
              for (var key in name_code_map) {
                  if (name_code_map[key] > 0) {
                      code_name_map[name_code_map[key]] = key;
                  }
              }
  
              var required_props = { code: code };
  
              if (typeof code === "number") {
                  if (code === 0) {
                      throw new AssertionError('Test bug: ambiguous DOMException code 0 passed to assert_throws()');
                  } else if (!(code in code_name_map)) {
                      throw new AssertionError('Test bug: unrecognized DOMException code "' + code + '" passed to assert_throws()');
                  }
                  name = code_name_map[code];
              } else if (typeof code === "string") {
                  if (!(name in name_code_map)) {
                      throw new AssertionError('Test bug: unrecognized DOMException code "' + code + '" passed to assert_throws()');
                  }
                  required_props.code = name_code_map[name];
              }
  
              if (required_props.code === 0 ||
                 ("name" in e &&
                  e.name !== e.name.toUpperCase() &&
                  e.name !== "DOMException")) {
                  // New style exception: also test the name property.
                  required_props.name = name;
              }
  
              //We'd like to test that e instanceof the appropriate interface,
              //but we can't, because we don't know what window it was created
              //in.  It might be an instanceof the appropriate interface on some
              //unknown other window.  TODO: Work around this somehow?
  
              for (var prop in required_props) {
                  assert(prop in e && e[prop] == required_props[prop],
                         "assert_throws", description,
                         "${func} threw ${e} that is not a DOMException " + code + ": property ${prop} is equal to ${actual}, expected ${expected}",
                         {func:func, e:e, prop:prop, actual:e[prop], expected:required_props[prop]});
              }
          }
      }
      expose(assert_throws, "assert_throws");
  
      /**
       * Assert a JS Error with the expected constructor is thrown.
       *
       * @param {object} constructor The expected exception constructor.
       * @param {Function} func Function which should throw.
       * @param {string} description Error description for the case that the error is not thrown.
       */
      function assert_throws_js(constructor, func, description)
      {
          assert_throws_js_impl(constructor, func, description,
                                "assert_throws_js");
      }
      expose(assert_throws_js, "assert_throws_js");
  
      /**
       * Like assert_throws_js but allows specifying the assertion type
       * (assert_throws_js or promise_rejects_js, in practice).
       */
      function assert_throws_js_impl(constructor, func, description,
                                     assertion_type)
      {
          try {
              func.call(this);
              assert(false, assertion_type, description,
                     "${func} did not throw", {func:func});
          } catch (e) {
              if (e instanceof AssertionError) {
                  throw e;
              }
  
              // Basic sanity-checks on the thrown exception.
              assert(typeof e === "object",
                     assertion_type, description,
                     "${func} threw ${e} with type ${type}, not an object",
                     {func:func, e:e, type:typeof e});
  
              assert(e !== null,
                     assertion_type, description,
                     "${func} threw null, not an object",
                     {func:func});
  
              // Basic sanity-check on the passed-in constructor
              assert(typeof constructor == "function",
                     assertion_type, description,
                     "${constructor} is not a constructor",
                     {constructor:constructor});
              var obj = constructor;
              while (obj) {
                  if (typeof obj === "function" &&
                      obj.name === "Error") {
                      break;
                  }
                  obj = Object.getPrototypeOf(obj);
              }
              assert(obj != null,
                     assertion_type, description,
                     "${constructor} is not an Error subtype",
                     {constructor:constructor});
  
              // And checking that our exception is reasonable
              assert(e.constructor === constructor &&
                     e.name === constructor.name,
                     assertion_type, description,
                     "${func} threw ${actual} (${actual_name}) expected instance of ${expected} (${expected_name})",
                     {func:func, actual:e, actual_name:e.name,
                      expected:constructor,
                      expected_name:constructor.name});
          }
      }
  
      /**
       * Assert a DOMException with the expected type is thrown.
       *
       * @param {number|string} type The expected exception name or code.  See the
       *        table of names and codes at
       *        https://heycam.github.io/webidl/#dfn-error-names-table
       *        If a number is passed it should be one of the numeric code values
       *        in that table (e.g. 3, 4, etc).  If a string is passed it can
       *        either be an exception name (e.g. "HierarchyRequestError",
       *        "WrongDocumentError") or the name of the corresponding error code
       *        (e.g. "HIERARCHY_REQUEST_ERR", "WRONG_DOCUMENT_ERR").
       * @param {Function} func Function which should throw.
       * @param {string} description Error description for the case that the error is not thrown.
       */
      function assert_throws_dom(type, func, description)
      {
          assert_throws_dom_impl(type, func, description, "assert_throws_dom")
      }
      expose(assert_throws_dom, "assert_throws_dom");
  
      /**
       * Like assert_throws_dom but allows specifying the assertion type
       * (assert_throws_dom or promise_rejects_dom, in practice).
       */
      function assert_throws_dom_impl(type, func, description, assertion_type)
      {
          try {
              func.call(this);
              assert(false, assertion_type, description,
                     "${func} did not throw", {func:func});
          } catch (e) {
              if (e instanceof AssertionError) {
                  throw e;
              }
  
              assert(typeof e === "object",
                     assertion_type, description,
                     "${func} threw ${e} with type ${type}, not an object",
                     {func:func, e:e, type:typeof e});
  
              assert(e !== null,
                     assertion_type, description,
                     "${func} threw null, not an object",
                     {func:func});
  
              // Sanity-check our type
              assert(typeof type == "number" ||
                     typeof type == "string",
                     assertion_type, description,
                     "${type} is not a number or string",
                     {type:type});
  
              var codename_name_map = {
                  INDEX_SIZE_ERR: 'IndexSizeError',
                  HIERARCHY_REQUEST_ERR: 'HierarchyRequestError',
                  WRONG_DOCUMENT_ERR: 'WrongDocumentError',
                  INVALID_CHARACTER_ERR: 'InvalidCharacterError',
                  NO_MODIFICATION_ALLOWED_ERR: 'NoModificationAllowedError',
                  NOT_FOUND_ERR: 'NotFoundError',
                  NOT_SUPPORTED_ERR: 'NotSupportedError',
                  INUSE_ATTRIBUTE_ERR: 'InUseAttributeError',
                  INVALID_STATE_ERR: 'InvalidStateError',
                  SYNTAX_ERR: 'SyntaxError',
                  INVALID_MODIFICATION_ERR: 'InvalidModificationError',
                  NAMESPACE_ERR: 'NamespaceError',
                  INVALID_ACCESS_ERR: 'InvalidAccessError',
                  TYPE_MISMATCH_ERR: 'TypeMismatchError',
                  SECURITY_ERR: 'SecurityError',
                  NETWORK_ERR: 'NetworkError',
                  ABORT_ERR: 'AbortError',
                  URL_MISMATCH_ERR: 'URLMismatchError',
                  QUOTA_EXCEEDED_ERR: 'QuotaExceededError',
                  TIMEOUT_ERR: 'TimeoutError',
                  INVALID_NODE_TYPE_ERR: 'InvalidNodeTypeError',
                  DATA_CLONE_ERR: 'DataCloneError'
              };
  
              var name_code_map = {
                  IndexSizeError: 1,
                  HierarchyRequestError: 3,
                  WrongDocumentError: 4,
                  InvalidCharacterError: 5,
                  NoModificationAllowedError: 7,
                  NotFoundError: 8,
                  NotSupportedError: 9,
                  InUseAttributeError: 10,
                  InvalidStateError: 11,
                  SyntaxError: 12,
                  InvalidModificationError: 13,
                  NamespaceError: 14,
                  InvalidAccessError: 15,
                  TypeMismatchError: 17,
                  SecurityError: 18,
                  NetworkError: 19,
                  AbortError: 20,
                  URLMismatchError: 21,
                  QuotaExceededError: 22,
                  TimeoutError: 23,
                  InvalidNodeTypeError: 24,
                  DataCloneError: 25,
  
                  EncodingError: 0,
                  NotReadableError: 0,
                  UnknownError: 0,
                  ConstraintError: 0,
                  DataError: 0,
                  TransactionInactiveError: 0,
                  ReadOnlyError: 0,
                  VersionError: 0,
                  OperationError: 0,
                  NotAllowedError: 0
              };
  
              var code_name_map = {};
              for (var key in name_code_map) {
                  if (name_code_map[key] > 0) {
                      code_name_map[name_code_map[key]] = key;
                  }
              }
  
              var required_props = {};
              var name;
  
              if (typeof type === "number") {
                  if (type === 0) {
                      throw new AssertionError('Test bug: ambiguous DOMException code 0 passed to assert_throws_dom()');
                  } else if (!(type in code_name_map)) {
                      throw new AssertionError('Test bug: unrecognized DOMException code "' + type + '" passed to assert_throws_dom()');
                  }
                  name = code_name_map[type];
                  required_props.code = type;
              } else if (typeof type === "string") {
                  name = type in codename_name_map ? codename_name_map[type] : type;
                  if (!(name in name_code_map)) {
                      throw new AssertionError('Test bug: unrecognized DOMException code name or name "' + type + '" passed to assert_throws_dom()');
                  }
  
                  required_props.code = name_code_map[name];
              }
  
              if (required_props.code === 0 ||
                 ("name" in e &&
                  e.name !== e.name.toUpperCase() &&
                  e.name !== "DOMException")) {
                  // New style exception: also test the name property.
                  required_props.name = name;
              }
  
              //We'd like to test that e instanceof the appropriate interface,
              //but we can't, because we don't know what window it was created
              //in.  It might be an instanceof the appropriate interface on some
              //unknown other window.  TODO: Work around this somehow?  Maybe have
              //the first arg just be a DOMException with the right name instead
              //of the string-or-code thing we have now?
  
              for (var prop in required_props) {
                  assert(prop in e && e[prop] == required_props[prop],
                         assertion_type, description,
                         "${func} threw ${e} that is not a DOMException " + type + ": property ${prop} is equal to ${actual}, expected ${expected}",
                         {func:func, e:e, prop:prop, actual:e[prop], expected:required_props[prop]});
              }
          }
      }
  
      /**
       * Assert the provided value is thrown.
       *
       * @param {value} exception The expected exception.
       * @param {Function} func Function which should throw.
       * @param {string} description Error description for the case that the error is not thrown.
       */
      function assert_throws_exactly(exception, func, description)
      {
          assert_throws_exactly_impl(exception, func, description,
                                     "assert_throws_exactly");
      }
      expose(assert_throws_exactly, "assert_throws_exactly");
  
      /**
       * Like assert_throws_exactly but allows specifying the assertion type
       * (assert_throws_exactly or promise_rejects_exactly, in practice).
       */
      function assert_throws_exactly_impl(exception, func, description,
                                          assertion_type)
      {
          try {
              func.call(this);
              assert(false, assertion_type, description,
                     "${func} did not throw", {func:func});
          } catch (e) {
              if (e instanceof AssertionError) {
                  throw e;
              }
  
              assert(same_value(e, exception), assertion_type, description,
                     "${func} threw ${e} but we expected it to throw ${exception}",
                     {func:func, e:e, exception:exception});
          }
      }
  
      function assert_unreached(description) {
           assert(false, "assert_unreached", description,
                  "Reached unreachable code");
      }
      expose(assert_unreached, "assert_unreached");
  
      function assert_any(assert_func, actual, expected_array)
      {
          var args = [].slice.call(arguments, 3);
          var errors = [];
          var passed = false;
          forEach(expected_array,
                  function(expected)
                  {
                      try {
                          assert_func.apply(this, [actual, expected].concat(args));
                          passed = true;
                      } catch (e) {
                          errors.push(e.message);
                      }
                  });
          if (!passed) {
              throw new AssertionError(errors.join("\n\n"));
          }
      }
      expose(assert_any, "assert_any");
  
      function assert_precondition(precondition, description) {
          if (!precondition) {
              throw new PreconditionFailedError(description);
          }
      }
      expose(assert_precondition, "assert_precondition");
  
      function Test(name, properties)
      {
          if (tests.file_is_test && tests.tests.length) {
              throw new Error("Tried to create a test with file_is_test");
          }
          this.name = name;
  
          this.phase = (tests.is_aborted || tests.phase === tests.phases.COMPLETE) ?
              this.phases.COMPLETE : this.phases.INITIAL;
  
          this.status = this.NOTRUN;
          this.timeout_id = null;
          this.index = null;
  
          this.properties = properties;
          this.timeout_length = settings.test_timeout;
          if (this.timeout_length !== null) {
              this.timeout_length *= tests.timeout_multiplier;
          }
  
          this.message = null;
          this.stack = null;
  
          this.steps = [];
          this._is_promise_test = false;
  
          this.cleanup_callbacks = [];
          this._user_defined_cleanup_count = 0;
          this._done_callbacks = [];
  
          // Tests declared following harness completion are likely an indication
          // of a programming error, but they cannot be reported
          // deterministically.
          if (tests.phase === tests.phases.COMPLETE) {
              return;
          }
  
          tests.push(this);
      }
  
      Test.statuses = {
          PASS:0,
          FAIL:1,
          TIMEOUT:2,
          NOTRUN:3,
          PRECONDITION_FAILED:4
      };
  
      Test.prototype = merge({}, Test.statuses);
  
      Test.prototype.phases = {
          INITIAL:0,
          STARTED:1,
          HAS_RESULT:2,
          CLEANING:3,
          COMPLETE:4
      };
  
      Test.prototype.structured_clone = function()
      {
          if (!this._structured_clone) {
              var msg = this.message;
              msg = msg ? String(msg) : msg;
              this._structured_clone = merge({
                  name:String(this.name),
                  properties:merge({}, this.properties),
                  phases:merge({}, this.phases)
              }, Test.statuses);
          }
          this._structured_clone.status = this.status;
          this._structured_clone.message = this.message;
          this._structured_clone.stack = this.stack;
          this._structured_clone.index = this.index;
          this._structured_clone.phase = this.phase;
          return this._structured_clone;
      };
  
      Test.prototype.step = function(func, this_obj)
      {
          if (this.phase > this.phases.STARTED) {
              return;
          }
          this.phase = this.phases.STARTED;
          //If we don't get a result before the harness times out that will be a test timeout
          this.set_status(this.TIMEOUT, "Test timed out");
  
          tests.started = true;
          tests.notify_test_state(this);
  
          if (this.timeout_id === null) {
              this.set_timeout();
          }
  
          this.steps.push(func);
  
          if (arguments.length === 1) {
              this_obj = this;
          }
  
          try {
              return func.apply(this_obj, Array.prototype.slice.call(arguments, 2));
          } catch (e) {
              if (this.phase >= this.phases.HAS_RESULT) {
                  return;
              }
              var status = e instanceof PreconditionFailedError ? this.PRECONDITION_FAILED : this.FAIL;
              var message = String((typeof e === "object" && e !== null) ? e.message : e);
              var stack = e.stack ? e.stack : null;
  
              this.set_status(status, message, stack);
              this.phase = this.phases.HAS_RESULT;
              this.done();
          }
      };
  
      Test.prototype.step_func = function(func, this_obj)
      {
          var test_this = this;
  
          if (arguments.length === 1) {
              this_obj = test_this;
          }
  
          return function()
          {
              return test_this.step.apply(test_this, [func, this_obj].concat(
                  Array.prototype.slice.call(arguments)));
          };
      };
  
      Test.prototype.step_func_done = function(func, this_obj)
      {
          var test_this = this;
  
          if (arguments.length === 1) {
              this_obj = test_this;
          }
  
          return function()
          {
              if (func) {
                  test_this.step.apply(test_this, [func, this_obj].concat(
                      Array.prototype.slice.call(arguments)));
              }
              test_this.done();
          };
      };
  
      Test.prototype.unreached_func = function(description)
      {
          return this.step_func(function() {
              assert_unreached(description);
          });
      };
  
      Test.prototype.step_timeout = function(f, timeout) {
          var test_this = this;
          var args = Array.prototype.slice.call(arguments, 2);
          return setTimeout(this.step_func(function() {
              return f.apply(test_this, args);
          }), timeout * tests.timeout_multiplier);
      }
  
      /*
       * Private method for registering cleanup functions. `testharness.js`
       * internals should use this method instead of the public `add_cleanup`
       * method in order to hide implementation details from the harness status
       * message in the case errors.
       */
      Test.prototype._add_cleanup = function(callback) {
          this.cleanup_callbacks.push(callback);
      };
  
      /*
       * Schedule a function to be run after the test result is known, regardless
       * of passing or failing state. The behavior of this function will not
       * influence the result of the test, but if an exception is thrown, the
       * test harness will report an error.
       */
      Test.prototype.add_cleanup = function(callback) {
          this._user_defined_cleanup_count += 1;
          this._add_cleanup(callback);
      };
  
      Test.prototype.set_timeout = function()
      {
          if (this.timeout_length !== null) {
              var this_obj = this;
              this.timeout_id = setTimeout(function()
                                           {
                                               this_obj.timeout();
                                           }, this.timeout_length);
          }
      };
  
      Test.prototype.set_status = function(status, message, stack)
      {
          this.status = status;
          this.message = message;
          this.stack = stack ? stack : null;
      };
  
      Test.prototype.timeout = function()
      {
          this.timeout_id = null;
          this.set_status(this.TIMEOUT, "Test timed out");
          this.phase = this.phases.HAS_RESULT;
          this.done();
      };
  
      Test.prototype.force_timeout = Test.prototype.timeout;
  
      /**
       * Update the test status, initiate "cleanup" functions, and signal test
       * completion.
       */
      Test.prototype.done = function()
      {
          if (this.phase >= this.phases.CLEANING) {
              return;
          }
  
          if (this.phase <= this.phases.STARTED) {
              this.set_status(this.PASS, null);
          }
  
          if (global_scope.clearTimeout) {
              clearTimeout(this.timeout_id);
          }
  
          this.cleanup();
      };
  
      function add_test_done_callback(test, callback)
      {
          if (test.phase === test.phases.COMPLETE) {
              callback();
              return;
          }
  
          test._done_callbacks.push(callback);
      }
  
      /*
       * Invoke all specified cleanup functions. If one or more produce an error,
       * the context is in an unpredictable state, so all further testing should
       * be cancelled.
       */
      Test.prototype.cleanup = function() {
          var error_count = 0;
          var bad_value_count = 0;
          function on_error() {
              error_count += 1;
              // Abort tests immediately so that tests declared within subsequent
              // cleanup functions are not run.
              tests.abort();
          }
          var this_obj = this;
          var results = [];
  
          this.phase = this.phases.CLEANING;
  
          forEach(this.cleanup_callbacks,
                  function(cleanup_callback) {
                      var result;
  
                      try {
                          result = cleanup_callback();
                      } catch (e) {
                          on_error();
                          return;
                      }
  
                      if (!is_valid_cleanup_result(this_obj, result)) {
                          bad_value_count += 1;
                          // Abort tests immediately so that tests declared
                          // within subsequent cleanup functions are not run.
                          tests.abort();
                      }
  
                      results.push(result);
                  });
  
          if (!this._is_promise_test) {
              cleanup_done(this_obj, error_count, bad_value_count);
          } else {
              all_async(results,
                        function(result, done) {
                            if (result && typeof result.then === "function") {
                                result
                                    .then(null, on_error)
                                    .then(done);
                            } else {
                                done();
                            }
                        },
                        function() {
                            cleanup_done(this_obj, error_count, bad_value_count);
                        });
          }
      };
  
      /**
       * Determine if the return value of a cleanup function is valid for a given
       * test. Any test may return the value `undefined`. Tests created with
       * `promise_test` may alternatively return "thenable" object values.
       */
      function is_valid_cleanup_result(test, result) {
          if (result === undefined) {
              return true;
          }
  
          if (test._is_promise_test) {
              return result && typeof result.then === "function";
          }
  
          return false;
      }
  
      function cleanup_done(test, error_count, bad_value_count) {
          if (error_count || bad_value_count) {
              var total = test._user_defined_cleanup_count;
  
              tests.status.status = tests.status.ERROR;
              tests.status.message = "Test named '" + test.name +
                  "' specified " + total +
                  " 'cleanup' function" + (total > 1 ? "s" : "");
  
              if (error_count) {
                  tests.status.message += ", and " + error_count + " failed";
              }
  
              if (bad_value_count) {
                  var type = test._is_promise_test ?
                     "non-thenable" : "non-undefined";
                  tests.status.message += ", and " + bad_value_count +
                      " returned a " + type + " value";
              }
  
              tests.status.message += ".";
  
              tests.status.stack = null;
          }
  
          test.phase = test.phases.COMPLETE;
          tests.result(test);
          forEach(test._done_callbacks,
                  function(callback) {
                      callback();
                  });
          test._done_callbacks.length = 0;
      }
  
      /*
       * A RemoteTest object mirrors a Test object on a remote worker. The
       * associated RemoteWorker updates the RemoteTest object in response to
       * received events. In turn, the RemoteTest object replicates these events
       * on the local document. This allows listeners (test result reporting
       * etc..) to transparently handle local and remote events.
       */
      function RemoteTest(clone) {
          var this_obj = this;
          Object.keys(clone).forEach(
                  function(key) {
                      this_obj[key] = clone[key];
                  });
          this.index = null;
          this.phase = this.phases.INITIAL;
          this.update_state_from(clone);
          this._done_callbacks = [];
          tests.push(this);
      }
  
      RemoteTest.prototype.structured_clone = function() {
          var clone = {};
          Object.keys(this).forEach(
                  (function(key) {
                      var value = this[key];
                      // `RemoteTest` instances are responsible for managing
                      // their own "done" callback functions, so those functions
                      // are not relevant in other execution contexts. Because of
                      // this (and because Function values cannot be serialized
                      // for cross-realm transmittance), the property should not
                      // be considered when cloning instances.
                      if (key === '_done_callbacks' ) {
                          return;
                      }
  
                      if (typeof value === "object" && value !== null) {
                          clone[key] = merge({}, value);
                      } else {
                          clone[key] = value;
                      }
                  }).bind(this));
          clone.phases = merge({}, this.phases);
          return clone;
      };
  
      /**
       * `RemoteTest` instances are objects which represent tests running in
       * another realm. They do not define "cleanup" functions (if necessary,
       * such functions are defined on the associated `Test` instance within the
       * external realm). However, `RemoteTests` may have "done" callbacks (e.g.
       * as attached by the `Tests` instance responsible for tracking the overall
       * test status in the parent realm). The `cleanup` method delegates to
       * `done` in order to ensure that such callbacks are invoked following the
       * completion of the `RemoteTest`.
       */
      RemoteTest.prototype.cleanup = function() {
          this.done();
      };
      RemoteTest.prototype.phases = Test.prototype.phases;
      RemoteTest.prototype.update_state_from = function(clone) {
          this.status = clone.status;
          this.message = clone.message;
          this.stack = clone.stack;
          if (this.phase === this.phases.INITIAL) {
              this.phase = this.phases.STARTED;
          }
      };
      RemoteTest.prototype.done = function() {
          this.phase = this.phases.COMPLETE;
  
          forEach(this._done_callbacks,
                  function(callback) {
                      callback();
                  });
      }
  
      /*
       * A RemoteContext listens for test events from a remote test context, such
       * as another window or a worker. These events are then used to construct
       * and maintain RemoteTest objects that mirror the tests running in the
       * remote context.
       *
       * An optional third parameter can be used as a predicate to filter incoming
       * MessageEvents.
       */
      function RemoteContext(remote, message_target, message_filter) {
          this.running = true;
          this.started = false;
          this.tests = new Array();
          this.early_exception = null;
  
          var this_obj = this;
          // If remote context is cross origin assigning to onerror is not
          // possible, so silently catch those errors.
          try {
            remote.onerror = function(error) { this_obj.remote_error(error); };
          } catch (e) {
            // Ignore.
          }
  
          // Keeping a reference to the remote object and the message handler until
          // remote_done() is seen prevents the remote object and its message channel
          // from going away before all the messages are dispatched.
          this.remote = remote;
          this.message_target = message_target;
          this.message_handler = function(message) {
              var passesFilter = !message_filter || message_filter(message);
              // The reference to the `running` property in the following
              // condition is unnecessary because that value is only set to
              // `false` after the `message_handler` function has been
              // unsubscribed.
              // TODO: Simplify the condition by removing the reference.
              if (this_obj.running && message.data && passesFilter &&
                  (message.data.type in this_obj.message_handlers)) {
                  this_obj.message_handlers[message.data.type].call(this_obj, message.data);
              }
          };
  
          if (self.Promise) {
              this.done = new Promise(function(resolve) {
                  this_obj.doneResolve = resolve;
              });
          }
  
          this.message_target.addEventListener("message", this.message_handler);
      }
  
      RemoteContext.prototype.remote_error = function(error) {
          if (error.preventDefault) {
              error.preventDefault();
          }
  
          // Defer interpretation of errors until the testing protocol has
          // started and the remote test's `allow_uncaught_exception` property
          // is available.
          if (!this.started) {
              this.early_exception = error;
          } else if (!this.allow_uncaught_exception) {
              this.report_uncaught(error);
          }
      };
  
      RemoteContext.prototype.report_uncaught = function(error) {
          var message = error.message || String(error);
          var filename = (error.filename ? " " + error.filename: "");
          // FIXME: Display remote error states separately from main document
          // error state.
          tests.set_status(tests.status.ERROR,
                           "Error in remote" + filename + ": " + message,
                           error.stack);
      };
  
      RemoteContext.prototype.start = function(data) {
          this.started = true;
          this.allow_uncaught_exception = data.properties.allow_uncaught_exception;
  
          if (this.early_exception && !this.allow_uncaught_exception) {
              this.report_uncaught(this.early_exception);
          }
      };
  
      RemoteContext.prototype.test_state = function(data) {
          var remote_test = this.tests[data.test.index];
          if (!remote_test) {
              remote_test = new RemoteTest(data.test);
              this.tests[data.test.index] = remote_test;
          }
          remote_test.update_state_from(data.test);
          tests.notify_test_state(remote_test);
      };
  
      RemoteContext.prototype.test_done = function(data) {
          var remote_test = this.tests[data.test.index];
          remote_test.update_state_from(data.test);
          remote_test.done();
          tests.result(remote_test);
      };
  
      RemoteContext.prototype.remote_done = function(data) {
          if (tests.status.status === null &&
              data.status.status !== data.status.OK) {
              tests.set_status(data.status.status, data.status.message, data.status.sack);
          }
  
          this.message_target.removeEventListener("message", this.message_handler);
          this.running = false;
  
          // If remote context is cross origin assigning to onerror is not
          // possible, so silently catch those errors.
          try {
            this.remote.onerror = null;
          } catch (e) {
            // Ignore.
          }
  
          this.remote = null;
          this.message_target = null;
          if (this.doneResolve) {
              this.doneResolve();
          }
  
          if (tests.all_done()) {
              tests.complete();
          }
      };
  
      RemoteContext.prototype.message_handlers = {
          start: RemoteContext.prototype.start,
          test_state: RemoteContext.prototype.test_state,
          result: RemoteContext.prototype.test_done,
          complete: RemoteContext.prototype.remote_done
      };
  
      /*
       * Harness
       */
  
      function TestsStatus()
      {
          this.status = null;
          this.message = null;
          this.stack = null;
      }
  
      TestsStatus.statuses = {
          OK:0,
          ERROR:1,
          TIMEOUT:2,
          PRECONDITION_FAILED:3
      };
  
      TestsStatus.prototype = merge({}, TestsStatus.statuses);
  
      TestsStatus.prototype.structured_clone = function()
      {
          if (!this._structured_clone) {
              var msg = this.message;
              msg = msg ? String(msg) : msg;
              this._structured_clone = merge({
                  status:this.status,
                  message:msg,
                  stack:this.stack
              }, TestsStatus.statuses);
          }
          return this._structured_clone;
      };
  
      function Tests()
      {
          this.tests = [];
          this.num_pending = 0;
  
          this.phases = {
              INITIAL:0,
              SETUP:1,
              HAVE_TESTS:2,
              HAVE_RESULTS:3,
              COMPLETE:4
          };
          this.phase = this.phases.INITIAL;
  
          this.properties = {};
  
          this.wait_for_finish = false;
          this.processing_callbacks = false;
  
          this.allow_uncaught_exception = false;
  
          this.file_is_test = false;
  
          this.timeout_multiplier = 1;
          this.timeout_length = test_environment.test_timeout();
          this.timeout_id = null;
  
          this.start_callbacks = [];
          this.test_state_callbacks = [];
          this.test_done_callbacks = [];
          this.all_done_callbacks = [];
  
          this.pending_remotes = [];
  
          this.status = new TestsStatus();
  
          var this_obj = this;
  
          test_environment.add_on_loaded_callback(function() {
              if (this_obj.all_done()) {
                  this_obj.complete();
              }
          });
  
          this.set_timeout();
      }
  
      Tests.prototype.setup = function(func, properties)
      {
          if (this.phase >= this.phases.HAVE_RESULTS) {
              return;
          }
  
          if (this.phase < this.phases.SETUP) {
              this.phase = this.phases.SETUP;
          }
  
          this.properties = properties;
  
          for (var p in properties) {
              if (properties.hasOwnProperty(p)) {
                  var value = properties[p];
                  if (p == "allow_uncaught_exception") {
                      this.allow_uncaught_exception = value;
                  } else if (p == "explicit_done" && value) {
                      this.wait_for_finish = true;
                  } else if (p == "explicit_timeout" && value) {
                      this.timeout_length = null;
                      if (this.timeout_id)
                      {
                          clearTimeout(this.timeout_id);
                      }
                  } else if (p == "single_test" && value) {
                      this.set_file_is_test();
                  } else if (p == "timeout_multiplier") {
                      this.timeout_multiplier = value;
                      if (this.timeout_length) {
                           this.timeout_length *= this.timeout_multiplier;
                      }
                  }
              }
          }
  
          if (func) {
              try {
                  func();
              } catch (e) {
                  this.status.status = e instanceof PreconditionFailedError ? this.status.PRECONDITION_FAILED : this.status.ERROR;
                  this.status.message = String(e);
                  this.status.stack = e.stack ? e.stack : null;
                  this.complete();
              }
          }
          this.set_timeout();
      };
  
      Tests.prototype.set_file_is_test = function() {
          if (this.tests.length > 0) {
              throw new Error("Tried to set file as test after creating a test");
          }
          this.wait_for_finish = true;
          this.file_is_test = true;
          // Create the test, which will add it to the list of tests
          async_test();
      };
  
      Tests.prototype.set_status = function(status, message, stack)
      {
          this.status.status = status;
          this.status.message = message;
          this.status.stack = stack ? stack : null;
      };
  
      Tests.prototype.set_timeout = function() {
          if (global_scope.clearTimeout) {
              var this_obj = this;
              clearTimeout(this.timeout_id);
              if (this.timeout_length !== null) {
                  this.timeout_id = setTimeout(function() {
                                                   this_obj.timeout();
                                               }, this.timeout_length);
              }
          }
      };
  
      Tests.prototype.timeout = function() {
          var test_in_cleanup = null;
  
          if (this.status.status === null) {
              forEach(this.tests,
                      function(test) {
                          // No more than one test is expected to be in the
                          // "CLEANUP" phase at any time
                          if (test.phase === test.phases.CLEANING) {
                              test_in_cleanup = test;
                          }
  
                          test.phase = test.phases.COMPLETE;
                      });
  
              // Timeouts that occur while a test is in the "cleanup" phase
              // indicate that some global state was not properly reverted. This
              // invalidates the overall test execution, so the timeout should be
              // reported as an error and cancel the execution of any remaining
              // tests.
              if (test_in_cleanup) {
                  this.status.status = this.status.ERROR;
                  this.status.message = "Timeout while running cleanup for " +
                      "test named \"" + test_in_cleanup.name + "\".";
                  tests.status.stack = null;
              } else {
                  this.status.status = this.status.TIMEOUT;
              }
          }
  
          this.complete();
      };
  
      Tests.prototype.end_wait = function()
      {
          this.wait_for_finish = false;
          if (this.all_done()) {
              this.complete();
          }
      };
  
      Tests.prototype.push = function(test)
      {
          if (this.phase < this.phases.HAVE_TESTS) {
              this.start();
          }
          this.num_pending++;
          test.index = this.tests.push(test);
          this.notify_test_state(test);
      };
  
      Tests.prototype.notify_test_state = function(test) {
          var this_obj = this;
          forEach(this.test_state_callbacks,
                  function(callback) {
                      callback(test, this_obj);
                  });
      };
  
      Tests.prototype.all_done = function() {
          return this.tests.length > 0 && test_environment.all_loaded &&
                  (this.num_pending === 0 || this.is_aborted) && !this.wait_for_finish &&
                  !this.processing_callbacks &&
                  !this.pending_remotes.some(function(w) { return w.running; });
      };
  
      Tests.prototype.start = function() {
          this.phase = this.phases.HAVE_TESTS;
          this.notify_start();
      };
  
      Tests.prototype.notify_start = function() {
          var this_obj = this;
          forEach (this.start_callbacks,
                   function(callback)
                   {
                       callback(this_obj.properties);
                   });
      };
  
      Tests.prototype.result = function(test)
      {
          // If the harness has already transitioned beyond the `HAVE_RESULTS`
          // phase, subsequent tests should not cause it to revert.
          if (this.phase <= this.phases.HAVE_RESULTS) {
              this.phase = this.phases.HAVE_RESULTS;
          }
          this.num_pending--;
          this.notify_result(test);
      };
  
      Tests.prototype.notify_result = function(test) {
          var this_obj = this;
          this.processing_callbacks = true;
          forEach(this.test_done_callbacks,
                  function(callback)
                  {
                      callback(test, this_obj);
                  });
          this.processing_callbacks = false;
          if (this_obj.all_done()) {
              this_obj.complete();
          }
      };
  
      Tests.prototype.complete = function() {
          if (this.phase === this.phases.COMPLETE) {
              return;
          }
          var this_obj = this;
          var all_complete = function() {
              this_obj.phase = this_obj.phases.COMPLETE;
              this_obj.notify_complete();
          };
          var incomplete = filter(this.tests,
                                  function(test) {
                                      return test.phase < test.phases.COMPLETE;
                                  });
  
          /**
           * To preserve legacy behavior, overall test completion must be
           * signaled synchronously.
           */
          if (incomplete.length === 0) {
              all_complete();
              return;
          }
  
          all_async(incomplete,
                    function(test, testDone)
                    {
                        if (test.phase === test.phases.INITIAL) {
                            test.phase = test.phases.COMPLETE;
                            testDone();
                        } else {
                            add_test_done_callback(test, testDone);
                            test.cleanup();
                        }
                    },
                    all_complete);
      };
  
      /**
       * Update the harness status to reflect an unrecoverable harness error that
       * should cancel all further testing. Update all previously-defined tests
       * which have not yet started to indicate that they will not be executed.
       */
      Tests.prototype.abort = function() {
          this.status.status = this.status.ERROR;
          this.is_aborted = true;
  
          forEach(this.tests,
                  function(test) {
                      if (test.phase === test.phases.INITIAL) {
                          test.phase = test.phases.COMPLETE;
                      }
                  });
      };
  
      /*
       * Determine if any tests share the same `name` property. Return an array
       * containing the names of any such duplicates.
       */
      Tests.prototype.find_duplicates = function() {
          var names = Object.create(null);
          var duplicates = [];
  
          forEach (this.tests,
                   function(test)
                   {
                       if (test.name in names && duplicates.indexOf(test.name) === -1) {
                          duplicates.push(test.name);
                       }
                       names[test.name] = true;
                   });
  
          return duplicates;
      };
  
      function code_unit_str(char) {
          return 'U+' + char.charCodeAt(0).toString(16);
      }
  
      function sanitize_unpaired_surrogates(str) {
          return str.replace(/([\ud800-\udbff])(?![\udc00-\udfff])/g,
                             function(_, unpaired)
                             {
                                 return code_unit_str(unpaired);
                             })
                    // This replacement is intentionally implemented without an
                    // ES2018 negative lookbehind assertion to support runtimes
                    // which do not yet implement that language feature.
                    .replace(/(^|[^\ud800-\udbff])([\udc00-\udfff])/g,
                             function(_, previous, unpaired) {
                                if (/[\udc00-\udfff]/.test(previous)) {
                                    previous = code_unit_str(previous);
                                }
  
                                return previous + code_unit_str(unpaired);
                             });
      }
  
      function sanitize_all_unpaired_surrogates(tests) {
          forEach (tests,
                   function (test)
                   {
                       var sanitized = sanitize_unpaired_surrogates(test.name);
  
                       if (test.name !== sanitized) {
                           test.name = sanitized;
                           delete test._structured_clone;
                       }
                   });
      }
  
      Tests.prototype.notify_complete = function() {
          var this_obj = this;
          var duplicates;
  
          if (this.status.status === null) {
              duplicates = this.find_duplicates();
  
              // Some transports adhere to UTF-8's restriction on unpaired
              // surrogates. Sanitize the titles so that the results can be
              // consistently sent via all transports.
              sanitize_all_unpaired_surrogates(this.tests);
  
              // Test names are presumed to be unique within test files--this
              // allows consumers to use them for identification purposes.
              // Duplicated names violate this expectation and should therefore
              // be reported as an error.
              if (duplicates.length) {
                  this.status.status = this.status.ERROR;
                  this.status.message =
                     duplicates.length + ' duplicate test name' +
                     (duplicates.length > 1 ? 's' : '') + ': "' +
                     duplicates.join('", "') + '"';
              } else {
                  this.status.status = this.status.OK;
              }
          }
  
          forEach (this.all_done_callbacks,
                   function(callback)
                   {
                       callback(this_obj.tests, this_obj.status);
                   });
      };
  
      /*
       * Constructs a RemoteContext that tracks tests from a specific worker.
       */
      Tests.prototype.create_remote_worker = function(worker) {
          var message_port;
  
          if (is_service_worker(worker)) {
              if (window.MessageChannel) {
                  // The ServiceWorker's implicit MessagePort is currently not
                  // reliably accessible from the ServiceWorkerGlobalScope due to
                  // Blink setting MessageEvent.source to null for messages sent
                  // via ServiceWorker.postMessage(). Until that's resolved,
                  // create an explicit MessageChannel and pass one end to the
                  // worker.
                  var message_channel = new MessageChannel();
                  message_port = message_channel.port1;
                  message_port.start();
                  worker.postMessage({type: "connect"}, [message_channel.port2]);
              } else {
                  // If MessageChannel is not available, then try the
                  // ServiceWorker.postMessage() approach using MessageEvent.source
                  // on the other end.
                  message_port = navigator.serviceWorker;
                  worker.postMessage({type: "connect"});
              }
          } else if (is_shared_worker(worker)) {
              message_port = worker.port;
              message_port.start();
          } else {
              message_port = worker;
          }
  
          return new RemoteContext(worker, message_port);
      };
  
      /*
       * Constructs a RemoteContext that tracks tests from a specific window.
       */
      Tests.prototype.create_remote_window = function(remote) {
          remote.postMessage({type: "getmessages"}, "*");
          return new RemoteContext(
              remote,
              window,
              function(msg) {
                  return msg.source === remote;
              }
          );
      };
  
      Tests.prototype.fetch_tests_from_worker = function(worker) {
          if (this.phase >= this.phases.COMPLETE) {
              return;
          }
  
          var remoteContext = this.create_remote_worker(worker);
          this.pending_remotes.push(remoteContext);
          return remoteContext.done;
      };
  
      function fetch_tests_from_worker(port) {
          return tests.fetch_tests_from_worker(port);
      }
      expose(fetch_tests_from_worker, 'fetch_tests_from_worker');
  
      Tests.prototype.fetch_tests_from_window = function(remote) {
          if (this.phase >= this.phases.COMPLETE) {
              return;
          }
  
          this.pending_remotes.push(this.create_remote_window(remote));
      };
  
      function fetch_tests_from_window(window) {
          tests.fetch_tests_from_window(window);
      }
      expose(fetch_tests_from_window, 'fetch_tests_from_window');
  
      function timeout() {
          if (tests.timeout_length === null) {
              tests.timeout();
          }
      }
      expose(timeout, 'timeout');
  
      function add_start_callback(callback) {
          tests.start_callbacks.push(callback);
      }
  
      function add_test_state_callback(callback) {
          tests.test_state_callbacks.push(callback);
      }
  
      function add_result_callback(callback) {
          tests.test_done_callbacks.push(callback);
      }
  
      function add_completion_callback(callback) {
          tests.all_done_callbacks.push(callback);
      }
  
      expose(add_start_callback, 'add_start_callback');
      expose(add_test_state_callback, 'add_test_state_callback');
      expose(add_result_callback, 'add_result_callback');
      expose(add_completion_callback, 'add_completion_callback');
  
      function remove(array, item) {
          var index = array.indexOf(item);
          if (index > -1) {
              array.splice(index, 1);
          }
      }
  
      function remove_start_callback(callback) {
          remove(tests.start_callbacks, callback);
      }
  
      function remove_test_state_callback(callback) {
          remove(tests.test_state_callbacks, callback);
      }
  
      function remove_result_callback(callback) {
          remove(tests.test_done_callbacks, callback);
      }
  
      function remove_completion_callback(callback) {
         remove(tests.all_done_callbacks, callback);
      }
  
      /*
       * Output listener
      */
  
      function Output() {
          this.output_document = document;
          this.output_node = null;
          this.enabled = settings.output;
          this.phase = this.INITIAL;
      }
  
      Output.prototype.INITIAL = 0;
      Output.prototype.STARTED = 1;
      Output.prototype.HAVE_RESULTS = 2;
      Output.prototype.COMPLETE = 3;
  
      Output.prototype.setup = function(properties) {
          if (this.phase > this.INITIAL) {
              return;
          }
  
          //If output is disabled in testharnessreport.js the test shouldn't be
          //able to override that
          this.enabled = this.enabled && (properties.hasOwnProperty("output") ?
                                          properties.output : settings.output);
      };
  
      Output.prototype.init = function(properties) {
          if (this.phase >= this.STARTED) {
              return;
          }
          if (properties.output_document) {
              this.output_document = properties.output_document;
          } else {
              this.output_document = document;
          }
          this.phase = this.STARTED;
      };
  
      Output.prototype.resolve_log = function() {
          var output_document;
          if (this.output_node) {
              return;
          }
          if (typeof this.output_document === "function") {
              output_document = this.output_document.apply(undefined);
          } else {
              output_document = this.output_document;
          }
          if (!output_document) {
              return;
          }
          var node = output_document.getElementById("log");
          if (!node) {
              if (output_document.readyState === "loading") {
                  return;
              }
              node = output_document.createElementNS("http://www.w3.org/1999/xhtml", "div");
              node.id = "log";
              if (output_document.body) {
                  output_document.body.appendChild(node);
              } else {
                  var root = output_document.documentElement;
                  var is_html = (root &&
                                 root.namespaceURI == "http://www.w3.org/1999/xhtml" &&
                                 root.localName == "html");
                  var is_svg = (output_document.defaultView &&
                                "SVGSVGElement" in output_document.defaultView &&
                                root instanceof output_document.defaultView.SVGSVGElement);
                  if (is_svg) {
                      var foreignObject = output_document.createElementNS("http://www.w3.org/2000/svg", "foreignObject");
                      foreignObject.setAttribute("width", "100%");
                      foreignObject.setAttribute("height", "100%");
                      root.appendChild(foreignObject);
                      foreignObject.appendChild(node);
                  } else if (is_html) {
                      root.appendChild(output_document.createElementNS("http://www.w3.org/1999/xhtml", "body"))
                          .appendChild(node);
                  } else {
                      root.appendChild(node);
                  }
              }
          }
          this.output_document = output_document;
          this.output_node = node;
      };
  
      Output.prototype.show_status = function() {
          if (this.phase < this.STARTED) {
              this.init();
          }
          if (!this.enabled || this.phase === this.COMPLETE) {
              return;
          }
          this.resolve_log();
          if (this.phase < this.HAVE_RESULTS) {
              this.phase = this.HAVE_RESULTS;
          }
          var done_count = tests.tests.length - tests.num_pending;
          if (this.output_node) {
              if (done_count < 100 ||
                  (done_count < 1000 && done_count % 100 === 0) ||
                  done_count % 1000 === 0) {
                  this.output_node.textContent = "Running, " +
                      done_count + " complete, " +
                      tests.num_pending + " remain";
              }
          }
      };
  
      Output.prototype.show_results = function (tests, harness_status) {
          if (this.phase >= this.COMPLETE) {
              return;
          }
          if (!this.enabled) {
              return;
          }
          if (!this.output_node) {
              this.resolve_log();
          }
          this.phase = this.COMPLETE;
  
          var log = this.output_node;
          if (!log) {
              return;
          }
          var output_document = this.output_document;
  
          while (log.lastChild) {
              log.removeChild(log.lastChild);
          }
  
          var stylesheet = output_document.createElementNS(xhtml_ns, "style");
          stylesheet.textContent = stylesheetContent;
          var heads = output_document.getElementsByTagName("head");
          if (heads.length) {
              heads[0].appendChild(stylesheet);
          }
  
          var status_text_harness = {};
          status_text_harness[harness_status.OK] = "OK";
          status_text_harness[harness_status.ERROR] = "Error";
          status_text_harness[harness_status.TIMEOUT] = "Timeout";
          status_text_harness[harness_status.PRECONDITION_FAILED] = "Precondition Failed";
  
          var status_text = {};
          status_text[Test.prototype.PASS] = "Pass";
          status_text[Test.prototype.FAIL] = "Fail";
          status_text[Test.prototype.TIMEOUT] = "Timeout";
          status_text[Test.prototype.NOTRUN] = "Not Run";
          status_text[Test.prototype.PRECONDITION_FAILED] = "Precondition Failed";
  
          var status_number = {};
          forEach(tests,
                  function(test) {
                      var status = status_text[test.status];
                      if (status_number.hasOwnProperty(status)) {
                          status_number[status] += 1;
                      } else {
                          status_number[status] = 1;
                      }
                  });
  
          function status_class(status)
          {
              return status.replace(/\s/g, '').toLowerCase();
          }
  
          var summary_template = ["section", {"id":"summary"},
                                  ["h2", {}, "Summary"],
                                  function()
                                  {
  
                                      var status = status_text_harness[harness_status.status];
                                      var rv = [["section", {},
                                                 ["p", {},
                                                  "Harness status: ",
                                                  ["span", {"class":status_class(status)},
                                                   status
                                                  ],
                                                 ]
                                                ]];
  
                                      if (harness_status.status === harness_status.ERROR) {
                                          rv[0].push(["pre", {}, harness_status.message]);
                                          if (harness_status.stack) {
                                              rv[0].push(["pre", {}, harness_status.stack]);
                                          }
                                      }
                                      return rv;
                                  },
                                  ["p", {}, "Found ${num_tests} tests"],
                                  function() {
                                      var rv = [["div", {}]];
                                      var i = 0;
                                      while (status_text.hasOwnProperty(i)) {
                                          if (status_number.hasOwnProperty(status_text[i])) {
                                              var status = status_text[i];
                                              rv[0].push(["div", {"class":status_class(status)},
                                                          ["label", {},
                                                           ["input", {type:"checkbox", checked:"checked"}],
                                                           status_number[status] + " " + status]]);
                                          }
                                          i++;
                                      }
                                      return rv;
                                  },
                                 ];
  
          log.appendChild(render(summary_template, {num_tests:tests.length}, output_document));
  
          forEach(output_document.querySelectorAll("section#summary label"),
                  function(element)
                  {
                      on_event(element, "click",
                               function(e)
                               {
                                   if (output_document.getElementById("results") === null) {
                                       e.preventDefault();
                                       return;
                                   }
                                   var result_class = element.parentNode.getAttribute("class");
                                   var style_element = output_document.querySelector("style#hide-" + result_class);
                                   var input_element = element.querySelector("input");
                                   if (!style_element && !input_element.checked) {
                                       style_element = output_document.createElementNS(xhtml_ns, "style");
                                       style_element.id = "hide-" + result_class;
                                       style_element.textContent = "table#results > tbody > tr."+result_class+"{display:none}";
                                       output_document.body.appendChild(style_element);
                                   } else if (style_element && input_element.checked) {
                                       style_element.parentNode.removeChild(style_element);
                                   }
                               });
                  });
  
          // This use of innerHTML plus manual escaping is not recommended in
          // general, but is necessary here for performance.  Using textContent
          // on each individual <td> adds tens of seconds of execution time for
          // large test suites (tens of thousands of tests).
          function escape_html(s)
          {
              return s.replace(/\&/g, "&amp;")
                  .replace(/</g, "&lt;")
                  .replace(/"/g, "&quot;")
                  .replace(/'/g, "&#39;");
          }
  
          function has_assertions()
          {
              for (var i = 0; i < tests.length; i++) {
                  if (tests[i].properties.hasOwnProperty("assert")) {
                      return true;
                  }
              }
              return false;
          }
  
          function get_assertion(test)
          {
              if (test.properties.hasOwnProperty("assert")) {
                  if (Array.isArray(test.properties.assert)) {
                      return test.properties.assert.join(' ');
                  }
                  return test.properties.assert;
              }
              return '';
          }
  
          log.appendChild(document.createElementNS(xhtml_ns, "section"));
          var assertions = has_assertions();
          var html = "<h2>Details</h2><table id='results' " + (assertions ? "class='assertions'" : "" ) + ">" +
              "<thead><tr><th>Result</th><th>Test Name</th>" +
              (assertions ? "<th>Assertion</th>" : "") +
              "<th>Message</th></tr></thead>" +
              "<tbody>";
          for (var i = 0; i < tests.length; i++) {
              html += '<tr class="' +
                  escape_html(status_class(status_text[tests[i].status])) +
                  '"><td>' +
                  escape_html(status_text[tests[i].status]) +
                  "</td><td>" +
                  escape_html(tests[i].name) +
                  "</td><td>" +
                  (assertions ? escape_html(get_assertion(tests[i])) + "</td><td>" : "") +
                  escape_html(tests[i].message ? tests[i].message : " ") +
                  (tests[i].stack ? "<pre>" +
                   escape_html(tests[i].stack) +
                   "</pre>": "") +
                  "</td></tr>";
          }
          html += "</tbody></table>";
          try {
              log.lastChild.innerHTML = html;
          } catch (e) {
              log.appendChild(document.createElementNS(xhtml_ns, "p"))
                 .textContent = "Setting innerHTML for the log threw an exception.";
              log.appendChild(document.createElementNS(xhtml_ns, "pre"))
                 .textContent = html;
          }
      };
  
      /*
       * Template code
       *
       * A template is just a JavaScript structure. An element is represented as:
       *
       * [tag_name, {attr_name:attr_value}, child1, child2]
       *
       * the children can either be strings (which act like text nodes), other templates or
       * functions (see below)
       *
       * A text node is represented as
       *
       * ["{text}", value]
       *
       * String values have a simple substitution syntax; ${foo} represents a variable foo.
       *
       * It is possible to embed logic in templates by using a function in a place where a
       * node would usually go. The function must either return part of a template or null.
       *
       * In cases where a set of nodes are required as output rather than a single node
       * with children it is possible to just use a list
       * [node1, node2, node3]
       *
       * Usage:
       *
       * render(template, substitutions) - take a template and an object mapping
       * variable names to parameters and return either a DOM node or a list of DOM nodes
       *
       * substitute(template, substitutions) - take a template and variable mapping object,
       * make the variable substitutions and return the substituted template
       *
       */
  
      function is_single_node(template)
      {
          return typeof template[0] === "string";
      }
  
      function substitute(template, substitutions)
      {
          if (typeof template === "function") {
              var replacement = template(substitutions);
              if (!replacement) {
                  return null;
              }
  
              return substitute(replacement, substitutions);
          }
  
          if (is_single_node(template)) {
              return substitute_single(template, substitutions);
          }
  
          return filter(map(template, function(x) {
                                return substitute(x, substitutions);
                            }), function(x) {return x !== null;});
      }
  
      function substitute_single(template, substitutions)
      {
          var substitution_re = /\$\{([^ }]*)\}/g;
  
          function do_substitution(input) {
              var components = input.split(substitution_re);
              var rv = [];
              for (var i = 0; i < components.length; i += 2) {
                  rv.push(components[i]);
                  if (components[i + 1]) {
                      rv.push(String(substitutions[components[i + 1]]));
                  }
              }
              return rv;
          }
  
          function substitute_attrs(attrs, rv)
          {
              rv[1] = {};
              for (var name in template[1]) {
                  if (attrs.hasOwnProperty(name)) {
                      var new_name = do_substitution(name).join("");
                      var new_value = do_substitution(attrs[name]).join("");
                      rv[1][new_name] = new_value;
                  }
              }
          }
  
          function substitute_children(children, rv)
          {
              for (var i = 0; i < children.length; i++) {
                  if (children[i] instanceof Object) {
                      var replacement = substitute(children[i], substitutions);
                      if (replacement !== null) {
                          if (is_single_node(replacement)) {
                              rv.push(replacement);
                          } else {
                              extend(rv, replacement);
                          }
                      }
                  } else {
                      extend(rv, do_substitution(String(children[i])));
                  }
              }
              return rv;
          }
  
          var rv = [];
          rv.push(do_substitution(String(template[0])).join(""));
  
          if (template[0] === "{text}") {
              substitute_children(template.slice(1), rv);
          } else {
              substitute_attrs(template[1], rv);
              substitute_children(template.slice(2), rv);
          }
  
          return rv;
      }
  
      function make_dom_single(template, doc)
      {
          var output_document = doc || document;
          var element;
          if (template[0] === "{text}") {
              element = output_document.createTextNode("");
              for (var i = 1; i < template.length; i++) {
                  element.data += template[i];
              }
          } else {
              element = output_document.createElementNS(xhtml_ns, template[0]);
              for (var name in template[1]) {
                  if (template[1].hasOwnProperty(name)) {
                      element.setAttribute(name, template[1][name]);
                  }
              }
              for (var i = 2; i < template.length; i++) {
                  if (template[i] instanceof Object) {
                      var sub_element = make_dom(template[i]);
                      element.appendChild(sub_element);
                  } else {
                      var text_node = output_document.createTextNode(template[i]);
                      element.appendChild(text_node);
                  }
              }
          }
  
          return element;
      }
  
      function make_dom(template, substitutions, output_document)
      {
          if (is_single_node(template)) {
              return make_dom_single(template, output_document);
          }
  
          return map(template, function(x) {
                         return make_dom_single(x, output_document);
                     });
      }
  
      function render(template, substitutions, output_document)
      {
          return make_dom(substitute(template, substitutions), output_document);
      }
  
      /*
       * Utility functions
       */
      function assert(expected_true, function_name, description, error, substitutions)
      {
          if (expected_true !== true) {
              var msg = make_message(function_name, description,
                                     error, substitutions);
              throw new AssertionError(msg);
          }
      }
  
      function AssertionError(message)
      {
          this.message = message;
          this.stack = this.get_stack();
      }
      expose(AssertionError, "AssertionError");
  
      AssertionError.prototype = Object.create(Error.prototype);
  
      AssertionError.prototype.get_stack = function() {
          var stack = new Error().stack;
          // IE11 does not initialize 'Error.stack' until the object is thrown.
          if (!stack) {
              try {
                  throw new Error();
              } catch (e) {
                  stack = e.stack;
              }
          }
  
          // 'Error.stack' is not supported in all browsers/versions
          if (!stack) {
              return "(Stack trace unavailable)";
          }
  
          var lines = stack.split("\n");
  
          // Create a pattern to match stack frames originating within testharness.js.  These include the
          // script URL, followed by the line/col (e.g., '/resources/testharness.js:120:21').
          // Escape the URL per http://stackoverflow.com/questions/3561493/is-there-a-regexp-escape-function-in-javascript
          // in case it contains RegExp characters.
          var script_url = get_script_url();
          var re_text = script_url ? script_url.replace(/[-\/\\^$*+?.()|[\]{}]/g, '\\$&') : "\\btestharness.js";
          var re = new RegExp(re_text + ":\\d+:\\d+");
  
          // Some browsers include a preamble that specifies the type of the error object.  Skip this by
          // advancing until we find the first stack frame originating from testharness.js.
          var i = 0;
          while (!re.test(lines[i]) && i < lines.length) {
              i++;
          }
  
          // Then skip the top frames originating from testharness.js to begin the stack at the test code.
          while (re.test(lines[i]) && i < lines.length) {
              i++;
          }
  
          // Paranoid check that we didn't skip all frames.  If so, return the original stack unmodified.
          if (i >= lines.length) {
              return stack;
          }
  
          return lines.slice(i).join("\n");
      }
  
      function PreconditionFailedError(message)
      {
          AssertionError.call(this, message);
      }
      PreconditionFailedError.prototype = Object.create(AssertionError.prototype);
      expose(PreconditionFailedError, "PreconditionFailedError");
  
      function make_message(function_name, description, error, substitutions)
      {
          for (var p in substitutions) {
              if (substitutions.hasOwnProperty(p)) {
                  substitutions[p] = format_value(substitutions[p]);
              }
          }
          var node_form = substitute(["{text}", "${function_name}: ${description}" + error],
                                     merge({function_name:function_name,
                                            description:(description?description + " ":"")},
                                            substitutions));
          return node_form.slice(1).join("");
      }
  
      function filter(array, callable, thisObj) {
          var rv = [];
          for (var i = 0; i < array.length; i++) {
              if (array.hasOwnProperty(i)) {
                  var pass = callable.call(thisObj, array[i], i, array);
                  if (pass) {
                      rv.push(array[i]);
                  }
              }
          }
          return rv;
      }
  
      function map(array, callable, thisObj)
      {
          var rv = [];
          rv.length = array.length;
          for (var i = 0; i < array.length; i++) {
              if (array.hasOwnProperty(i)) {
                  rv[i] = callable.call(thisObj, array[i], i, array);
              }
          }
          return rv;
      }
  
      function extend(array, items)
      {
          Array.prototype.push.apply(array, items);
      }
  
      function forEach(array, callback, thisObj)
      {
          for (var i = 0; i < array.length; i++) {
              if (array.hasOwnProperty(i)) {
                  callback.call(thisObj, array[i], i, array);
              }
          }
      }
  
      /**
       * Immediately invoke a "iteratee" function with a series of values in
       * parallel and invoke a final "done" function when all of the "iteratee"
       * invocations have signaled completion.
       *
       * If all callbacks complete synchronously (or if no callbacks are
       * specified), the `done_callback` will be invoked synchronously. It is the
       * responsibility of the caller to ensure asynchronicity in cases where
       * that is desired.
       *
       * @param {array} value Zero or more values to use in the invocation of
       *                      `iter_callback`
       * @param {function} iter_callback A function that will be invoked once for
       *                                 each of the provided `values`. Two
       *                                 arguments will be available in each
       *                                 invocation: the value from `values` and
       *                                 a function that must be invoked to
       *                                 signal completion
       * @param {function} done_callback A function that will be invoked after
       *                                 all operations initiated by the
       *                                 `iter_callback` function have signaled
       *                                 completion
       */
      function all_async(values, iter_callback, done_callback)
      {
          var remaining = values.length;
  
          if (remaining === 0) {
              done_callback();
          }
  
          forEach(values,
                  function(element) {
                      var invoked = false;
                      var elDone = function() {
                          if (invoked) {
                              return;
                          }
  
                          invoked = true;
                          remaining -= 1;
  
                          if (remaining === 0) {
                              done_callback();
                          }
                      };
  
                      iter_callback(element, elDone);
                  });
      }
  
      function merge(a,b)
      {
          var rv = {};
          var p;
          for (p in a) {
              rv[p] = a[p];
          }
          for (p in b) {
              rv[p] = b[p];
          }
          return rv;
      }
  
      function expose(object, name)
      {
          var components = name.split(".");
          var target = global_scope;
          for (var i = 0; i < components.length - 1; i++) {
              if (!(components[i] in target)) {
                  target[components[i]] = {};
              }
              target = target[components[i]];
          }
          target[components[components.length - 1]] = object;
      }
  
      function is_same_origin(w) {
          try {
              'random_prop' in w;
              return true;
          } catch (e) {
              return false;
          }
      }
  
      /** Returns the 'src' URL of the first <script> tag in the page to include the file 'testharness.js'. */
      function get_script_url()
      {
          if (!('document' in global_scope)) {
              return undefined;
          }
  
          var scripts = document.getElementsByTagName("script");
          for (var i = 0; i < scripts.length; i++) {
              var src;
              if (scripts[i].src) {
                  src = scripts[i].src;
              } else if (scripts[i].href) {
                  //SVG case
                  src = scripts[i].href.baseVal;
              }
  
              var matches = src && src.match(/^(.*\/|)testharness\.js$/);
              if (matches) {
                  return src;
              }
          }
          return undefined;
      }
  
      /** Returns the <title> or filename or "Untitled" */
      function get_title()
      {
          if ('document' in global_scope) {
              //Don't use document.title to work around an Opera bug in XHTML documents
              var title = document.getElementsByTagName("title")[0];
              if (title && title.firstChild && title.firstChild.data) {
                  return title.firstChild.data;
              }
          }
          if ('META_TITLE' in global_scope && META_TITLE) {
              return META_TITLE;
          }
          if ('location' in global_scope) {
              return location.pathname.substring(location.pathname.lastIndexOf('/') + 1, location.pathname.indexOf('.'));
          }
          return "Untitled";
      }
  
      function supports_post_message(w)
      {
          var supports;
          var type;
          // Given IE implements postMessage across nested iframes but not across
          // windows or tabs, you can't infer cross-origin communication from the presence
          // of postMessage on the current window object only.
          //
          // Touching the postMessage prop on a window can throw if the window is
          // not from the same origin AND post message is not supported in that
          // browser. So just doing an existence test here won't do, you also need
          // to wrap it in a try..catch block.
          try {
              type = typeof w.postMessage;
              if (type === "function") {
                  supports = true;
              }
  
              // IE8 supports postMessage, but implements it as a host object which
              // returns "object" as its `typeof`.
              else if (type === "object") {
                  supports = true;
              }
  
              // This is the case where postMessage isn't supported AND accessing a
              // window property across origins does NOT throw (e.g. old Safari browser).
              else {
                  supports = false;
              }
          } catch (e) {
              // This is the case where postMessage isn't supported AND accessing a
              // window property across origins throws (e.g. old Firefox browser).
              supports = false;
          }
          return supports;
      }
  
      /**
       * Setup globals
       */
  
      var tests = new Tests();
  
      if (global_scope.addEventListener) {
          var error_handler = function(error, message, stack) {
              var precondition_failed = error instanceof PreconditionFailedError;
              if (tests.file_is_test) {
                  var test = tests.tests[0];
                  if (test.phase >= test.phases.HAS_RESULT) {
                      return;
                  }
                  var status = precondition_failed ? test.PRECONDITION_FAILED : test.FAIL;
                  test.set_status(status, message, stack);
                  test.phase = test.phases.HAS_RESULT;
              } else if (!tests.allow_uncaught_exception) {
                  var status = precondition_failed ? tests.status.PRECONDITION_FAILED : tests.status.ERROR;
                  tests.status.status = status;
                  tests.status.message = message;
                  tests.status.stack = stack;
              }
  
              // Do not transition to the "complete" phase if the test has been
              // configured to allow uncaught exceptions. This gives the test an
              // opportunity to define subtests based on the exception reporting
              // behavior.
              if (!tests.allow_uncaught_exception) {
                  done();
              }
          };
  
          addEventListener("error", function(e) {
              var message = e.message;
              var stack;
              if (e.error && e.error.stack) {
                  stack = e.error.stack;
              } else {
                  stack = e.filename + ":" + e.lineno + ":" + e.colno;
              }
              error_handler(e.error, message, stack);
          }, false);
  
          addEventListener("unhandledrejection", function(e) {
              var message;
              if (e.reason && e.reason.message) {
                  message = "Unhandled rejection: " + e.reason.message;
              } else {
                  message = "Unhandled rejection";
              }
              var stack;
              if (e.reason && e.reason.stack) {
                  stack = e.reason.stack;
              }
              error_handler(e.reason, message, stack);
          }, false);
      }
  
      test_environment.on_tests_ready();
  
      /**
       * Stylesheet
       */
       var stylesheetContent = "\
  html {\
      font-family:DejaVu Sans, Bitstream Vera Sans, Arial, Sans;\
  }\
  \
  #log .warning,\
  #log .warning a {\
    color: black;\
    background: yellow;\
  }\
  \
  #log .error,\
  #log .error a {\
    color: white;\
    background: red;\
  }\
  \
  section#summary {\
      margin-bottom:1em;\
  }\
  \
  table#results {\
      border-collapse:collapse;\
      table-layout:fixed;\
      width:100%;\
  }\
  \
  table#results th:first-child,\
  table#results td:first-child {\
      width:8em;\
  }\
  \
  table#results th:last-child,\
  table#results td:last-child {\
      width:50%;\
  }\
  \
  table#results.assertions th:last-child,\
  table#results.assertions td:last-child {\
      width:35%;\
  }\
  \
  table#results th {\
      padding:0;\
      padding-bottom:0.5em;\
      border-bottom:medium solid black;\
  }\
  \
  table#results td {\
      padding:1em;\
      padding-bottom:0.5em;\
      border-bottom:thin solid black;\
  }\
  \
  tr.pass > td:first-child {\
      color:green;\
  }\
  \
  tr.fail > td:first-child {\
      color:red;\
  }\
  \
  tr.timeout > td:first-child {\
      color:red;\
  }\
  \
  tr.notrun > td:first-child {\
      color:blue;\
  }\
  \
  tr.preconditionfailed > td:first-child {\
      color:blue;\
  }\
  \
  .pass > td:first-child, .fail > td:first-child, .timeout > td:first-child, .notrun > td:first-child, .preconditionfailed > td:first-child {\
      font-variant:small-caps;\
  }\
  \
  table#results span {\
      display:block;\
  }\
  \
  table#results span.expected {\
      font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;\
      white-space:pre;\
  }\
  \
  table#results span.actual {\
      font-family:DejaVu Sans Mono, Bitstream Vera Sans Mono, Monospace;\
      white-space:pre;\
  }\
  \
  span.ok {\
      color:green;\
  }\
  \
  tr.error {\
      color:red;\
  }\
  \
  span.timeout {\
      color:red;\
  }\
  \
  span.ok, span.timeout, span.error {\
      font-variant:small-caps;\
  }\
  ";
  
  })(this);
  // vim: set expandtab shiftwidth=4 tabstop=4:
  