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.functions.Function;
  import io.reactivex.rxjava3.testsupport.TestHelper;
  
  public class SingleMapTest extends RxJavaTest {
  
      @Test
      public void mapValue() {
          Single.just(1).map(new Function<Integer, Integer>() {
              @Override
              public Integer apply(final Integer integer) throws Exception {
                  if (integer == 1) {
                      return 2;
                  }
  
                  return 1;
              }
          })
          .test()
          .assertResult(2);
      }
  
      @Test
      public void mapValueNull() {
          Single.just(1).map(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(final Integer integer) throws Exception {
                  return null;
              }
          })
          .to(TestHelper.<SingleSource<Integer>>testConsumer())
          .assertNoValues()
          .assertError(NullPointerException.class)
          .assertErrorMessage("The mapper function returned a null value.");
      }
  
      @Test
      public void mapValueErrorThrown() {
          Single.just(1).map(new Function<Integer, SingleSource<Integer>>() {
              @Override
              public SingleSource<Integer> apply(final Integer integer) throws Exception {
                  throw new RuntimeException("something went terribly wrong!");
              }
          })
          .to(TestHelper.<SingleSource<Integer>>testConsumer())
          .assertNoValues()
          .assertError(RuntimeException.class)
          .assertErrorMessage("something went terribly wrong!");
      }
  
      @Test
      public void mapError() {
          RuntimeException exception = new RuntimeException("test");
  
          Single.error(exception).map(new Function<Object, Object>() {
              @Override
              public Object apply(final Object integer) throws Exception {
                  return new Object();
              }
          })
          .test()
          .assertError(exception);
      }
  }
  