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.internal.operators.completable;
  
  import static org.junit.Assert.assertEquals;
  import static org.mockito.ArgumentMatchers.any;
  import static org.mockito.Mockito.*;
  
  import java.util.concurrent.*;
  import java.util.concurrent.atomic.AtomicInteger;
  
  import org.junit.Test;
  import org.mockito.invocation.InvocationOnMock;
  import org.mockito.stubbing.Answer;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.disposables.Disposable;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.observers.TestObserver;
  import io.reactivex.rxjava3.schedulers.Schedulers;
  import io.reactivex.rxjava3.testsupport.*;
  
  public class CompletableFromCallableTest extends RxJavaTest {
  
      @Test
      public void fromCallable() {
          final AtomicInteger atomicInteger = new AtomicInteger();
  
          Completable.fromCallable(new Callable<Object>() {
              @Override
              public Object call() throws Exception {
                  atomicInteger.incrementAndGet();
                  return null;
              }
          })
              .test()
              .assertResult();
  
          assertEquals(1, atomicInteger.get());
      }
  
      @Test
      public void fromCallableTwice() {
          final AtomicInteger atomicInteger = new AtomicInteger();
  
          Callable<Object> callable = new Callable<Object>() {
              @Override
              public Object call() throws Exception {
                  atomicInteger.incrementAndGet();
                  return null;
              }
          };
  
          Completable.fromCallable(callable)
              .test()
              .assertResult();
  
          assertEquals(1, atomicInteger.get());
  
          Completable.fromCallable(callable)
              .test()
              .assertResult();
  
          assertEquals(2, atomicInteger.get());
      }
  
      @Test
      public void fromCallableInvokesLazy() {
          final AtomicInteger atomicInteger = new AtomicInteger();
  
          Completable completable = Completable.fromCallable(new Callable<Object>() {
              @Override
              public Object call() throws Exception {
                  atomicInteger.incrementAndGet();
                  return null;
              }
          });
  
          assertEquals(0, atomicInteger.get());
  
          completable
              .test()
              .assertResult();
  
          assertEquals(1, atomicInteger.get());
      }
  
      @Test
      public void fromCallableThrows() {
          Completable.fromCallable(new Callable<Object>() {
              @Override
              public Object call() throws Exception {
                  throw new UnsupportedOperationException();
              }
          })
              .test()
              .assertFailure(UnsupportedOperationException.class);
      }
  
      @SuppressWarnings("unchecked")
      @Test
      public void shouldNotDeliverResultIfSubscriberUnsubscribedBeforeEmission() throws Exception {
          Callable<String> func = mock(Callable.class);
  
          final CountDownLatch funcLatch = new CountDownLatch(1);
          final CountDownLatch observerLatch = new CountDownLatch(1);
  
          when(func.call()).thenAnswer(new Answer<String>() {
              @Override
              public String answer(InvocationOnMock invocation) throws Throwable {
                  observerLatch.countDown();
  
                  try {
                      funcLatch.await();
                  } catch (InterruptedException e) {
                      // It's okay, unsubscription causes Thread interruption
  
                      // Restoring interruption status of the Thread
                      Thread.currentThread().interrupt();
                  }
  
                  return "should_not_be_delivered";
              }
          });
  
          Completable fromCallableObservable = Completable.fromCallable(func);
  
          Observer<Object> observer = TestHelper.mockObserver();
  
          TestObserver<String> outer = new TestObserver<>(observer);
  
          fromCallableObservable
                  .subscribeOn(Schedulers.computation())
                  .subscribe(outer);
  
          // Wait until func will be invoked
          observerLatch.await();
  
          // Unsubscribing before emission
          outer.dispose();
  
          // Emitting result
          funcLatch.countDown();
  
          // func must be invoked
          verify(func).call();
  
          // Observer must not be notified at all
          verify(observer).onSubscribe(any(Disposable.class));
          verifyNoMoreInteractions(observer);
      }
  
      @Test
      @SuppressUndeliverable
      public void fromActionErrorsDisposed() {
          final AtomicInteger calls = new AtomicInteger();
          Completable.fromCallable(new Callable<Object>() {
              @Override
              public Object call() throws Exception {
                  calls.incrementAndGet();
                  throw new TestException();
              }
          })
          .test(true)
          .assertEmpty();
  
          assertEquals(1, calls.get());
      }
  }
  