code: /*
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.rxjava3.testsupport;
  
  import java.util.concurrent.atomic.*;
  
  import org.reactivestreams.*;
  
  import io.reactivex.rxjava3.core.FlowableSubscriber;
  import io.reactivex.rxjava3.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.rxjava3.operators.QueueFuseable;
  import io.reactivex.rxjava3.operators.QueueSubscription;
  
  /**
   * An extended test subscriber that records events and allows making assertions about them.
   *
   * <p>You can override the onSubscribe, onNext, onError, onComplete, request and
   * cancel methods but not the others (this is by design).
   *
   * <p>The TestSubscriber implements Disposable for convenience where dispose calls cancel.
   *
   * <p>When calling the default request method, you are requesting on behalf of the
   * wrapped actual subscriber.
   *
   * @param <T> the value type
   */
  public class TestSubscriberEx<T>
  extends BaseTestConsumerEx<T, TestSubscriberEx<T>>
  implements FlowableSubscriber<T>, Subscription {
      /** The actual subscriber to forward events to. */
      private final Subscriber<? super T> downstream;
  
      /** Makes sure the incoming Subscriptions get cancelled immediately. */
      private volatile boolean cancelled;
  
      /** Holds the current subscription if any. */
      private final AtomicReference<Subscription> upstream;
  
      /** Holds the requested amount until a subscription arrives. */
      private final AtomicLong missedRequested;
  
      private QueueSubscription<T> qs;
  
      /**
       * Constructs a non-forwarding TestSubscriber with an initial request value of {@link Long#MAX_VALUE}.
       */
      public TestSubscriberEx() {
          this(EmptySubscriber.INSTANCE, Long.MAX_VALUE);
      }
  
      /**
       * Constructs a non-forwarding TestSubscriber with the specified initial request value.
       * <p>The TestSubscriber doesn't validate the initialRequest value so one can
       * test sources with invalid values as well.
       * @param initialRequest the initial request value
       */
      public TestSubscriberEx(long initialRequest) {
          this(EmptySubscriber.INSTANCE, initialRequest);
      }
  
      /**
       * Constructs a forwarding TestSubscriber but leaves the requesting to the wrapped subscriber.
       * @param downstream the actual Subscriber to forward events to
       */
      public TestSubscriberEx(Subscriber<? super T> downstream) {
          this(downstream, Long.MAX_VALUE);
      }
  
      /**
       * Constructs a forwarding TestSubscriber with the specified initial request value.
       * <p>The TestSubscriber doesn't validate the initialRequest value so one can
       * test sources with invalid values as well.
       * @param actual the actual Subscriber to forward events to
       * @param initialRequest the initial request value
       */
      public TestSubscriberEx(Subscriber<? super T> actual, long initialRequest) {
          super();
          if (initialRequest < 0) {
              throw new IllegalArgumentException("Negative initial request not allowed");
          }
          this.downstream = actual;
          this.upstream = new AtomicReference<>();
          this.missedRequested = new AtomicLong(initialRequest);
      }
  
      @SuppressWarnings("unchecked")
      @Override
      public void onSubscribe(Subscription s) {
          lastThread = Thread.currentThread();
  
          if (s == null) {
              errors.add(new NullPointerException("onSubscribe received a null Subscription"));
              return;
          }
          if (!upstream.compareAndSet(null, s)) {
              s.cancel();
              if (upstream.get() != SubscriptionHelper.CANCELLED) {
                  errors.add(new IllegalStateException("onSubscribe received multiple subscriptions: " + s));
              }
              return;
          }
  
          if (initialFusionMode != 0) {
              if (s instanceof QueueSubscription) {
                  qs = (QueueSubscription<T>)s;
  
                  int m = qs.requestFusion(initialFusionMode);
                  establishedFusionMode = m;
  
                  if (m == QueueFuseable.SYNC) {
                      checkSubscriptionOnce = true;
                      lastThread = Thread.currentThread();
                      try {
                          T t;
                          while ((t = qs.poll()) != null) {
                              values.add(t);
                          }
                          completions++;
                      } catch (Throwable ex) {
                          // Exceptions.throwIfFatal(e); TODO add fatal exceptions?
                          errors.add(ex);
                      }
                      return;
                  }
              }
          }
  
          downstream.onSubscribe(s);
  
          long mr = missedRequested.getAndSet(0L);
          if (mr != 0L) {
              s.request(mr);
          }
  
          onStart();
      }
  
      /**
       * Called after the onSubscribe is called and handled.
       */
      protected void onStart() {
  
      }
  
      @Override
      public void onNext(T t) {
          if (!checkSubscriptionOnce) {
              checkSubscriptionOnce = true;
              if (upstream.get() == null) {
                  errors.add(new IllegalStateException("onSubscribe not called in proper order"));
              }
          }
          lastThread = Thread.currentThread();
  
          if (establishedFusionMode == QueueFuseable.ASYNC) {
              try {
                  while ((t = qs.poll()) != null) {
                      values.add(t);
                  }
              } catch (Throwable ex) {
                  // Exceptions.throwIfFatal(e); TODO add fatal exceptions?
                  errors.add(ex);
                  qs.cancel();
              }
              return;
          }
  
          values.add(t);
  
          if (t == null) {
              errors.add(new NullPointerException("onNext received a null value"));
          }
  
          downstream.onNext(t);
      }
  
      @Override
      public void onError(Throwable t) {
          if (!checkSubscriptionOnce) {
              checkSubscriptionOnce = true;
              if (upstream.get() == null) {
                  errors.add(new NullPointerException("onSubscribe not called in proper order"));
              }
          }
          try {
              lastThread = Thread.currentThread();
              errors.add(t);
  
              if (t == null) {
                  errors.add(new IllegalStateException("onError received a null Throwable"));
              }
  
              downstream.onError(t);
          } finally {
              done.countDown();
          }
      }
  
      @Override
      public void onComplete() {
          if (!checkSubscriptionOnce) {
              checkSubscriptionOnce = true;
              if (upstream.get() == null) {
                  errors.add(new IllegalStateException("onSubscribe not called in proper order"));
              }
          }
          try {
              lastThread = Thread.currentThread();
              completions++;
  
              downstream.onComplete();
          } finally {
              done.countDown();
          }
      }
  
      @Override
      public final void request(long n) {
          SubscriptionHelper.deferredRequest(upstream, missedRequested, n);
      }
  
      @Override
      public final void cancel() {
          if (!cancelled) {
              cancelled = true;
              SubscriptionHelper.cancel(upstream);
          }
      }
  
      /**
       * Returns true if this TestSubscriber has been cancelled.
       * @return true if this TestSubscriber has been cancelled
       */
      public final boolean isCancelled() {
          return cancelled;
      }
  
      @Override
      protected final void dispose() {
          cancel();
      }
  
      @Override
      protected final boolean isDisposed() {
          return cancelled;
      }
  
      // state retrieval methods
  
      /**
       * Returns true if this TestSubscriber received a subscription.
       * @return true if this TestSubscriber received a subscription
       */
      public final boolean hasSubscription() {
          return upstream.get() != null;
      }
  
      // assertion methods
  
      /**
       * Assert that the onSubscribe method was called exactly once.
       * @return this
       */
      @Override
      public final TestSubscriberEx<T> assertSubscribed() {
          if (upstream.get() == null) {
              throw fail("Not subscribed!");
          }
          return this;
      }
  
      /**
       * Assert that the onSubscribe method hasn't been called at all.
       * @return this
       */
      public final TestSubscriberEx<T> assertNotSubscribed() {
          if (upstream.get() != null) {
              throw fail("Subscribed!");
          } else
          if (!errors.isEmpty()) {
              throw fail("Not subscribed but errors found");
          }
          return this;
      }
  
      /**
       * Sets the initial fusion mode if the upstream supports fusion.
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use SubscriberFusion to work with such tests.
       * @param mode the mode to establish, see the {@link QueueSubscription} constants
       * @return this
       */
      public final TestSubscriberEx<T> setInitialFusionMode(int mode) {
          this.initialFusionMode = mode;
          return this;
      }
  
      /**
       * Asserts that the given fusion mode has been established
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use SubscriberFusion to work with such tests.
       * @param mode the expected mode
       * @return this
       */
      public final TestSubscriberEx<T> assertFusionMode(int mode) {
          int m = establishedFusionMode;
          if (m != mode) {
              if (qs != null) {
                  throw new AssertionError("\nexpected: " + fusionModeToString(mode)
                  + "\ngot: " + fusionModeToString(m) + "; Fusion mode different");
              } else {
                  throw fail("Upstream is not fuseable");
              }
          }
          return this;
      }
  
      /**
       * Assert that the upstream is a fuseable source.
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use SubscriberFusion to work with such tests.
       * @return this
       */
      public final TestSubscriberEx<T> assertFuseable() {
          if (qs == null) {
              throw new AssertionError("Upstream is not fuseable.");
          }
          return this;
      }
  
      /**
       * Assert that the upstream is not a fuseable source.
       * <p>Package-private: avoid leaking the now internal fusion properties into the public API.
       * Use SubscriberFusion to work with such tests.
       * @return this
       */
      public final TestSubscriberEx<T> assertNotFuseable() {
          if (qs != null) {
              throw new AssertionError("Upstream is fuseable.");
          }
          return this;
      }
  
      /**
       * Calls {@link #request(long)} and returns this.
       * <p>History: 2.0.1 - experimental
       * @param n the request amount
       * @return this
       * @since 2.1
       */
      public final TestSubscriberEx<T> requestMore(long n) {
          request(n);
          return this;
      }
  
      /**
       * A subscriber that ignores all events and does not report errors.
       */
      enum EmptySubscriber implements FlowableSubscriber<Object> {
          INSTANCE;
  
          @Override
          public void onSubscribe(Subscription s) {
          }
  
          @Override
          public void onNext(Object t) {
          }
  
          @Override
          public void onError(Throwable t) {
          }
  
          @Override
          public void onComplete() {
          }
      }
  }
  