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.single;
  
  import org.junit.Test;
  
  import io.reactivex.rxjava3.core.*;
  import io.reactivex.rxjava3.exceptions.TestException;
  import io.reactivex.rxjava3.functions.Function;
  import io.reactivex.rxjava3.testsupport.TestHelper;
  
  public class SingleFlatMapMaybeTest extends RxJavaTest {
      @Test
      public void flatMapMaybeValue() {
          Single.just(1).flatMapMaybe(new Function<Integer, MaybeSource<Integer>>() {
              @Override public MaybeSource<Integer> apply(final Integer integer) throws Exception {
                  if (integer == 1) {
                      return Maybe.just(2);
                  }
  
                  return Maybe.just(1);
              }
          })
              .test()
              .assertResult(2);
      }
  
      @Test
      public void flatMapMaybeValueDifferentType() {
          Single.just(1).flatMapMaybe(new Function<Integer, MaybeSource<String>>() {
              @Override public MaybeSource<String> apply(final Integer integer) throws Exception {
                  if (integer == 1) {
                      return Maybe.just("2");
                  }
  
                  return Maybe.just("1");
              }
          })
              .test()
              .assertResult("2");
      }
  
      @Test
      public void flatMapMaybeValueNull() {
          Single.just(1).flatMapMaybe(new Function<Integer, MaybeSource<Integer>>() {
              @Override public MaybeSource<Integer> apply(final Integer integer) throws Exception {
                  return null;
              }
          })
              .to(TestHelper.<Integer>testConsumer())
              .assertNoValues()
              .assertError(NullPointerException.class)
              .assertErrorMessage("The mapper returned a null MaybeSource");
      }
  
      @Test
      public void flatMapMaybeValueErrorThrown() {
          Single.just(1).flatMapMaybe(new Function<Integer, MaybeSource<Integer>>() {
              @Override public MaybeSource<Integer> apply(final Integer integer) throws Exception {
                  throw new RuntimeException("something went terribly wrong!");
              }
          })
              .to(TestHelper.<Integer>testConsumer())
              .assertNoValues()
              .assertError(RuntimeException.class)
              .assertErrorMessage("something went terribly wrong!");
      }
  
      @Test
      public void flatMapMaybeError() {
          RuntimeException exception = new RuntimeException("test");
  
          Single.error(exception).flatMapMaybe(new Function<Object, MaybeSource<Object>>() {
              @Override public MaybeSource<Object> apply(final Object integer) throws Exception {
                  return Maybe.just(new Object());
              }
          })
              .test()
              .assertError(exception);
      }
  
      @Test
      public void dispose() {
          TestHelper.checkDisposed(Single.just(1).flatMapMaybe(new Function<Integer, MaybeSource<Integer>>() {
              @Override
              public MaybeSource<Integer> apply(Integer v) throws Exception {
                  return Maybe.just(1);
              }
          }));
      }
  
      @Test
      public void doubleOnSubscribe() {
          TestHelper.checkDoubleOnSubscribeSingleToMaybe(new Function<Single<Integer>, MaybeSource<Integer>>() {
              @Override
              public MaybeSource<Integer> apply(Single<Integer> v) throws Exception {
                  return v.flatMapMaybe(new Function<Integer, MaybeSource<Integer>>() {
                      @Override
                      public MaybeSource<Integer> apply(Integer v) throws Exception {
                          return Maybe.just(1);
                      }
                  });
              }
          });
      }
  
      @Test
      public void mapsToError() {
          Single.just(1).flatMapMaybe(new Function<Integer, MaybeSource<Integer>>() {
              @Override
              public MaybeSource<Integer> apply(Integer v) throws Exception {
                  return Maybe.error(new TestException());
              }
          })
          .test()
          .assertFailure(TestException.class);
      }
  
      @Test
      public void mapsToEmpty() {
          Single.just(1).flatMapMaybe(new Function<Integer, MaybeSource<Integer>>() {
              @Override
              public MaybeSource<Integer> apply(Integer v) throws Exception {
                  return Maybe.empty();
              }
          })
          .test()
          .assertResult();
      }
  }
  