title: Spring Reactive test doesn't result in an expected error
body: <p>I am writing unit tests for one of our reactive methods. This method depends on another service. I have mocked this service. While running the test, i am getting the below error:
  <code>java.lang.AssertionError: expectation "expectError(Class)" failed (expected: onError(MyException); actual: onComplete())</code>.<br>
  Here is what I have tried:<br>
  <strong>Method(ReactiveService.class):</strong></p>
  
  <pre><code>@Autowired
  private Service serice;
  
  public Mono&lt;MyObject&gt; save(List&lt;MyObject&gt; arg1, String arg2) {
      return SomeUtil.user()
              .map(user -&gt; service.save(arg1, arg2, user))
              .subscribeOn(scheduler)
              .doOnError(e -&gt; {
                  throw new MyException(MyObject.class, "save object", e);
              });
  }
  </code></pre>
  
  <p><strong>Test:</strong></p>
  
  <pre><code>@Mock
  Service service;
  
  @InjectMocks
  ReactiveService reactiveService;
  
  @Test
  public void unit_test(){
      when(service.save(any(), any(), any())).thenThrow(new RuntimeException());
      Mono&lt;MyObject&gt; result = reactiveService.save(arg1, arg2);
      StepVerifier.create(result)
          .expectError(MyException.class)
          .verify();
  }
  </code></pre>
  
  <p>From the error I understood that, no signal is received from the method. But I am not getting what I have missed here.</p>