text: #!/usr/bin/env python
  import argparse
  import atexit
  import copy
  import os
  import shutil
  import subprocess
  import sys
  import tempfile
  import warnings
  
  import django
  from django.apps import apps
  from django.conf import settings
  from django.db import connection, connections
  from django.test import TestCase, TransactionTestCase
  from django.test.runner import default_test_processes
  from django.test.selenium import SeleniumTestCaseBase
  from django.test.utils import get_runner
  from django.utils.deprecation import RemovedInDjango30Warning
  from django.utils.log import DEFAULT_LOGGING
  
  # Make deprecation warnings errors to ensure no usage of deprecated features.
  warnings.simplefilter("error", RemovedInDjango30Warning)
  # Make runtime warning errors to ensure no usage of error prone patterns.
  warnings.simplefilter("error", RuntimeWarning)
  # Ignore known warnings in test dependencies.
  warnings.filterwarnings("ignore", "'U' mode is deprecated", DeprecationWarning, module='docutils.io')
  
  RUNTESTS_DIR = os.path.abspath(os.path.dirname(__file__))
  
  TEMPLATE_DIR = os.path.join(RUNTESTS_DIR, 'templates')
  
  # Create a specific subdirectory for the duration of the test suite.
  TMPDIR = tempfile.mkdtemp(prefix='django_')
  # Set the TMPDIR environment variable in addition to tempfile.tempdir
  # so that children processes inherit it.
  tempfile.tempdir = os.environ['TMPDIR'] = TMPDIR
  
  # Removing the temporary TMPDIR.
  atexit.register(shutil.rmtree, TMPDIR)
  
  
  SUBDIRS_TO_SKIP = [
      'data',
      'import_error_package',
      'test_discovery_sample',
      'test_discovery_sample2',
  ]
  
  ALWAYS_INSTALLED_APPS = [
      'django.contrib.contenttypes',
      'django.contrib.auth',
      'django.contrib.sites',
      'django.contrib.sessions',
      'django.contrib.messages',
      'django.contrib.admin.apps.SimpleAdminConfig',
      'django.contrib.staticfiles',
  ]
  
  ALWAYS_MIDDLEWARE = [
      'django.contrib.sessions.middleware.SessionMiddleware',
      'django.middleware.common.CommonMiddleware',
      'django.middleware.csrf.CsrfViewMiddleware',
      'django.contrib.auth.middleware.AuthenticationMiddleware',
      'django.contrib.messages.middleware.MessageMiddleware',
  ]
  
  # Need to add the associated contrib app to INSTALLED_APPS in some cases to
  # avoid "RuntimeError: Model class X doesn't declare an explicit app_label
  # and isn't in an application in INSTALLED_APPS."
  CONTRIB_TESTS_TO_APPS = {
      'flatpages_tests': 'django.contrib.flatpages',
      'redirects_tests': 'django.contrib.redirects',
  }
  
  
  def get_test_modules():
      modules = []
      discovery_paths = [(None, RUNTESTS_DIR)]
      if connection.features.gis_enabled:
          # GIS tests are in nested apps
          discovery_paths.append(('gis_tests', os.path.join(RUNTESTS_DIR, 'gis_tests')))
      else:
          SUBDIRS_TO_SKIP.append('gis_tests')
  
      for modpath, dirpath in discovery_paths:
          for f in os.listdir(dirpath):
              if ('.' in f or
                      os.path.basename(f) in SUBDIRS_TO_SKIP or
                      os.path.isfile(f) or
                      not os.path.exists(os.path.join(dirpath, f, '__init__.py'))):
                  continue
              modules.append((modpath, f))
      return modules
  
  
  def get_installed():
      return [app_config.name for app_config in apps.get_app_configs()]
  
  
  def setup(verbosity, test_labels, parallel):
      # Reduce the given test labels to just the app module path.
      test_labels_set = set()
      for label in test_labels:
          bits = label.split('.')[:1]
          test_labels_set.add('.'.join(bits))
  
      if verbosity >= 1:
          msg = "Testing against Django installed in '%s'" % os.path.dirname(django.__file__)
          max_parallel = default_test_processes() if parallel == 0 else parallel
          if max_parallel > 1:
              msg += " with up to %d processes" % max_parallel
          print(msg)
  
      # Force declaring available_apps in TransactionTestCase for faster tests.
      def no_available_apps(self):
          raise Exception("Please define available_apps in TransactionTestCase "
                          "and its subclasses.")
      TransactionTestCase.available_apps = property(no_available_apps)
      TestCase.available_apps = None
  
      state = {
          'INSTALLED_APPS': settings.INSTALLED_APPS,
          'ROOT_URLCONF': getattr(settings, "ROOT_URLCONF", ""),
          'TEMPLATES': settings.TEMPLATES,
          'LANGUAGE_CODE': settings.LANGUAGE_CODE,
          'STATIC_URL': settings.STATIC_URL,
          'STATIC_ROOT': settings.STATIC_ROOT,
          'MIDDLEWARE': settings.MIDDLEWARE,
      }
  
      # Redirect some settings for the duration of these tests.
      settings.INSTALLED_APPS = ALWAYS_INSTALLED_APPS
      settings.ROOT_URLCONF = 'urls'
      settings.STATIC_URL = '/static/'
      settings.STATIC_ROOT = os.path.join(TMPDIR, 'static')
      settings.TEMPLATES = [{
          'BACKEND': 'django.template.backends.django.DjangoTemplates',
          'DIRS': [TEMPLATE_DIR],
          'APP_DIRS': True,
          'OPTIONS': {
              'context_processors': [
                  'django.template.context_processors.debug',
                  'django.template.context_processors.request',
                  'django.contrib.auth.context_processors.auth',
                  'django.contrib.messages.context_processors.messages',
              ],
          },
      }]
      settings.LANGUAGE_CODE = 'en'
      settings.SITE_ID = 1
      settings.MIDDLEWARE = ALWAYS_MIDDLEWARE
      settings.MIGRATION_MODULES = {
          # This lets us skip creating migrations for the test models as many of
          # them depend on one of the following contrib applications.
          'auth': None,
          'contenttypes': None,
          'sessions': None,
      }
      log_config = copy.deepcopy(DEFAULT_LOGGING)
      # Filter out non-error logging so we don't have to capture it in lots of
      # tests.
      log_config['loggers']['django']['level'] = 'ERROR'
      settings.LOGGING = log_config
      settings.SILENCED_SYSTEM_CHECKS = [
          'fields.W342',  # ForeignKey(unique=True) -> OneToOneField
      ]
  
      # Load all the ALWAYS_INSTALLED_APPS.
      django.setup()
  
      # It would be nice to put this validation earlier but it must come after
      # django.setup() so that connection.features.gis_enabled can be accessed
      # without raising AppRegistryNotReady when running gis_tests in isolation
      # on some backends (e.g. PostGIS).
      if 'gis_tests' in test_labels_set and not connection.features.gis_enabled:
          print('Aborting: A GIS database backend is required to run gis_tests.')
          sys.exit(1)
  
      # Load all the test model apps.
      test_modules = get_test_modules()
  
      installed_app_names = set(get_installed())
      for modpath, module_name in test_modules:
          if modpath:
              module_label = modpath + '.' + module_name
          else:
              module_label = module_name
          # if the module (or an ancestor) was named on the command line, or
          # no modules were named (i.e., run all), import
          # this module and add it to INSTALLED_APPS.
          if not test_labels:
              module_found_in_labels = True
          else:
              module_found_in_labels = any(
                  # exact match or ancestor match
                  module_label == label or module_label.startswith(label + '.')
                  for label in test_labels_set)
  
          if module_name in CONTRIB_TESTS_TO_APPS and module_found_in_labels:
              settings.INSTALLED_APPS.append(CONTRIB_TESTS_TO_APPS[module_name])
  
          if module_found_in_labels and module_label not in installed_app_names:
              if verbosity >= 2:
                  print("Importing application %s" % module_name)
              settings.INSTALLED_APPS.append(module_label)
  
      # Add contrib.gis to INSTALLED_APPS if needed (rather than requiring
      # @override_settings(INSTALLED_APPS=...) on all test cases.
      gis = 'django.contrib.gis'
      if connection.features.gis_enabled and gis not in settings.INSTALLED_APPS:
          if verbosity >= 2:
              print("Importing application %s" % gis)
          settings.INSTALLED_APPS.append(gis)
  
      apps.set_installed_apps(settings.INSTALLED_APPS)
  
      return state
  
  
  def teardown(state):
      # Restore the old settings.
      for key, value in state.items():
          setattr(settings, key, value)
      # Discard the multiprocessing.util finalizer that tries to remove a
      # temporary directory that's already removed by this script's
      # atexit.register(shutil.rmtree, TMPDIR) handler. Prevents
      # FileNotFoundError at the end of a test run on Python 3.6+ (#27890).
      from multiprocessing.util import _finalizer_registry
      _finalizer_registry.pop((-100, 0), None)
  
  
  def actual_test_processes(parallel):
      if parallel == 0:
          # This doesn't work before django.setup() on some databases.
          if all(conn.features.can_clone_databases for conn in connections.all()):
              return default_test_processes()
          else:
              return 1
      else:
          return parallel
  
  
  class ActionSelenium(argparse.Action):
      """
      Validate the comma-separated list of requested browsers.
      """
      def __call__(self, parser, namespace, values, option_string=None):
          browsers = values.split(',')
          for browser in browsers:
              try:
                  SeleniumTestCaseBase.import_webdriver(browser)
              except ImportError:
                  raise argparse.ArgumentError(self, "Selenium browser specification '%s' is not valid." % browser)
          setattr(namespace, self.dest, browsers)
  
  
  def django_tests(verbosity, interactive, failfast, keepdb, reverse,
                   test_labels, debug_sql, parallel, tags, exclude_tags):
      state = setup(verbosity, test_labels, parallel)
      extra_tests = []
  
      # Run the test suite, including the extra validation tests.
      if not hasattr(settings, 'TEST_RUNNER'):
          settings.TEST_RUNNER = 'django.test.runner.DiscoverRunner'
      TestRunner = get_runner(settings)
  
      test_runner = TestRunner(
          verbosity=verbosity,
          interactive=interactive,
          failfast=failfast,
          keepdb=keepdb,
          reverse=reverse,
          debug_sql=debug_sql,
          parallel=actual_test_processes(parallel),
          tags=tags,
          exclude_tags=exclude_tags,
      )
      failures = test_runner.run_tests(
          test_labels or get_installed(),
          extra_tests=extra_tests,
      )
      teardown(state)
      return failures
  
  
  def get_subprocess_args(options):
      subprocess_args = [
          sys.executable, __file__, '--settings=%s' % options.settings
      ]
      if options.failfast:
          subprocess_args.append('--failfast')
      if options.verbosity:
          subprocess_args.append('--verbosity=%s' % options.verbosity)
      if not options.interactive:
          subprocess_args.append('--noinput')
      if options.tags:
          subprocess_args.append('--tag=%s' % options.tags)
      if options.exclude_tags:
          subprocess_args.append('--exclude_tag=%s' % options.exclude_tags)
      return subprocess_args
  
  
  def bisect_tests(bisection_label, options, test_labels, parallel):
      state = setup(options.verbosity, test_labels, parallel)
  
      test_labels = test_labels or get_installed()
  
      print('***** Bisecting test suite: %s' % ' '.join(test_labels))
  
      # Make sure the bisection point isn't in the test list
      # Also remove tests that need to be run in specific combinations
      for label in [bisection_label, 'model_inheritance_same_model_name']:
          try:
              test_labels.remove(label)
          except ValueError:
              pass
  
      subprocess_args = get_subprocess_args(options)
  
      iteration = 1
      while len(test_labels) > 1:
          midpoint = len(test_labels) // 2
          test_labels_a = test_labels[:midpoint] + [bisection_label]
          test_labels_b = test_labels[midpoint:] + [bisection_label]
          print('***** Pass %da: Running the first half of the test suite' % iteration)
          print('***** Test labels: %s' % ' '.join(test_labels_a))
          failures_a = subprocess.call(subprocess_args + test_labels_a)
  
          print('***** Pass %db: Running the second half of the test suite' % iteration)
          print('***** Test labels: %s' % ' '.join(test_labels_b))
          print('')
          failures_b = subprocess.call(subprocess_args + test_labels_b)
  
          if failures_a and not failures_b:
              print("***** Problem found in first half. Bisecting again...")
              iteration += 1
              test_labels = test_labels_a[:-1]
          elif failures_b and not failures_a:
              print("***** Problem found in second half. Bisecting again...")
              iteration += 1
              test_labels = test_labels_b[:-1]
          elif failures_a and failures_b:
              print("***** Multiple sources of failure found")
              break
          else:
              print("***** No source of failure found... try pair execution (--pair)")
              break
  
      if len(test_labels) == 1:
          print("***** Source of error: %s" % test_labels[0])
      teardown(state)
  
  
  def paired_tests(paired_test, options, test_labels, parallel):
      state = setup(options.verbosity, test_labels, parallel)
  
      test_labels = test_labels or get_installed()
  
      print('***** Trying paired execution')
  
      # Make sure the constant member of the pair isn't in the test list
      # Also remove tests that need to be run in specific combinations
      for label in [paired_test, 'model_inheritance_same_model_name']:
          try:
              test_labels.remove(label)
          except ValueError:
              pass
  
      subprocess_args = get_subprocess_args(options)
  
      for i, label in enumerate(test_labels):
          print('***** %d of %d: Check test pairing with %s' % (
                i + 1, len(test_labels), label))
          failures = subprocess.call(subprocess_args + [label, paired_test])
          if failures:
              print('***** Found problem pair with %s' % label)
              return
  
      print('***** No problem pair found')
      teardown(state)
  
  
  if __name__ == "__main__":
      parser = argparse.ArgumentParser(description="Run the Django test suite.")
      parser.add_argument(
          'modules', nargs='*', metavar='module',
          help='Optional path(s) to test modules; e.g. "i18n" or '
               '"i18n.tests.TranslationTests.test_lazy_objects".',
      )
      parser.add_argument(
          '-v', '--verbosity', default=1, type=int, choices=[0, 1, 2, 3],
          help='Verbosity level; 0=minimal output, 1=normal output, 2=all output',
      )
      parser.add_argument(
          '--noinput', action='store_false', dest='interactive',
          help='Tells Django to NOT prompt the user for input of any kind.',
      )
      parser.add_argument(
          '--failfast', action='store_true', dest='failfast',
          help='Tells Django to stop running the test suite after first failed test.',
      )
      parser.add_argument(
          '-k', '--keepdb', action='store_true', dest='keepdb',
          help='Tells Django to preserve the test database between runs.',
      )
      parser.add_argument(
          '--settings',
          help='Python path to settings module, e.g. "myproject.settings". If '
               'this isn\'t provided, either the DJANGO_SETTINGS_MODULE '
               'environment variable or "test_sqlite" will be used.',
      )
      parser.add_argument(
          '--bisect',
          help='Bisect the test suite to discover a test that causes a test '
               'failure when combined with the named test.',
      )
      parser.add_argument(
          '--pair',
          help='Run the test suite in pairs with the named test to find problem pairs.',
      )
      parser.add_argument(
          '--reverse', action='store_true',
          help='Sort test suites and test cases in opposite order to debug '
               'test side effects not apparent with normal execution lineup.',
      )
      parser.add_argument(
          '--selenium', dest='selenium', action=ActionSelenium, metavar='BROWSERS',
          help='A comma-separated list of browsers to run the Selenium tests against.',
      )
      parser.add_argument(
          '--debug-sql', action='store_true', dest='debug_sql',
          help='Turn on the SQL query logger within tests.',
      )
      parser.add_argument(
          '--parallel', dest='parallel', nargs='?', default=0, type=int,
          const=default_test_processes(), metavar='N',
          help='Run tests using up to N parallel processes.',
      )
      parser.add_argument(
          '--tag', dest='tags', action='append',
          help='Run only tests with the specified tags. Can be used multiple times.',
      )
      parser.add_argument(
          '--exclude-tag', dest='exclude_tags', action='append',
          help='Do not run tests with the specified tag. Can be used multiple times.',
      )
  
      options = parser.parse_args()
  
      # Allow including a trailing slash on app_labels for tab completion convenience
      options.modules = [os.path.normpath(labels) for labels in options.modules]
  
      if options.settings:
          os.environ['DJANGO_SETTINGS_MODULE'] = options.settings
      else:
          if "DJANGO_SETTINGS_MODULE" not in os.environ:
              os.environ['DJANGO_SETTINGS_MODULE'] = 'test_sqlite'
          options.settings = os.environ['DJANGO_SETTINGS_MODULE']
  
      if options.selenium:
          if not options.tags:
              options.tags = ['selenium']
          elif 'selenium' not in options.tags:
              options.tags.append('selenium')
          SeleniumTestCaseBase.browsers = options.selenium
  
      if options.bisect:
          bisect_tests(options.bisect, options, options.modules, options.parallel)
      elif options.pair:
          paired_tests(options.pair, options, options.modules, options.parallel)
      else:
          failures = django_tests(
              options.verbosity, options.interactive, options.failfast,
              options.keepdb, options.reverse, options.modules,
              options.debug_sql, options.parallel, options.tags,
              options.exclude_tags,
          )
          if failures:
              sys.exit(1)
  