title: JUnit AssertionError: Expecting code to raise a throwable
body: <p>I am trying to write a test for a method that throws custom exception. It fails with Assertion error. What could be done to properly catch the exception and pass the test?</p>
  
  <p>Service method:</p>
  
  <pre><code>@Service
  public class CustomServiceImpl implements CustomService {
      @Autowired
      UserUtil userUtil;
      public ResultDTO getResultDto (String type, Long id) throws CustomException {
          User user = userUtil.getCurrentUser();
          if (user == null) {
              throw new CustomException("User does not exist");
          }
      }
  }
  </code></pre>
  
  <p>Test method:</p>
  
  <pre><code>@MockBean
  CustomServiceImpl  customServiceImpl ;
  
  @Test
  public void test01_getResultDto() {
      UserUtil userUtil = Mockito.mock(UserUtil.class);
      Mockito.when(userUtil.getCurrentUser()).thenReturn(null);
      Assertions.assertThatThrownBy(() -&gt; customServiceImpl.getResultDto (Mockito.anyString(), Mockito.anyLong())) 
          .isInstanceOf(CustomException .class)
          .hasMessage("User does not exist");
  }
  </code></pre>
  
  <p>This test fails with the following error:</p>
  
  <pre><code>java.lang.AssertionError: Expecting code to raise a throwable.
      at com.ps.service.CustomServiceImplTest.test01_getResultDto(CustomServiceImplTest.java:62)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
      at java.lang.reflect.Method.invoke(Method.java:498)
      at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
      at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
      at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
      at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
      at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
      at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
      at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
      at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
      at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
      at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
      at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
      at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
      at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
      at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
      at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
      at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
      at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
      at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)
      at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
      at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)
  
  
  </code></pre>
  
  <p>--------------------------- EDIT ------------------------
  Changed the code Test to include the following</p>
  
  <pre><code>@Mock
  UserUtil userUtil;
  @InjectMocks
  CustomServiceImpl cutomServiceImpl;
  
  @Before
  public void setUp() throws Exception {
      MockitoAnnotations.initMocks(this);
  }
  
  @Test
  public void test01_getResultDto() {
      when(userUtil.getCurrentUser()).thenReturn(null);
      assertThatThrownBy(() -&gt; customServiceImpl.getResultDto ("type", 1L)) 
          .isInstanceOf(CustomException .class)
          .hasMessage("User does not exist");
  }
  </code></pre>
  
  <p>Seems to be working.</p>
  
  <p>Thanks to the advice in comments.</p>