Mockito How to mock and assert a thrown exception

Question

I m using mockito in a junit test  How do you make an exception happen and then assert that it has  generic pseudo-code

User · Answer

Make the exception happen like this   when obj someMethod    thenThrow new AnException       Verify it has happened either by asserting that your test will throw such an exception    Test expected   AnException class    Or by normal mock verification   verify obj  someMethod      The latter option is required if your test is designed to prove intermediate code handles the exception  i e  the exception won t be thrown from your test method

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BDD Style Solution  Updated to Java 8   Mockito alone is not the best solution for handling exceptions  use Mockito with Catch-Exception   Mockito   Catch-Exception   AssertJ  given otherServiceMock bar    willThrow new MyException      when    - gt  myService foo      then caughtException    isInstanceOf MyException class     Sample code   Mockito   Catch-Exception   Assertj full sample   Dependencies   eu codearte catch-exception catch-exception 2 0 org assertj assertj-core 3 12 2

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Unrelated to mockito  one can catch the exception and assert its properties   To verify that the exception did happen  assert a false condition within the try block after the statement that throws the exception

User · Answer

Updated answer for 06 19 2015  if you re using java 8   Just use assertj  Using assertj-core-3 0 0        Java 8 Lambdas    Test public void shouldThrowIllegalArgumentExceptionWhenPassingBadArg     assertThatThrownBy    - gt  myService sumTingWong  badArg                                       isInstanceOf IllegalArgumentException class       Reference  http   blog codeleak pl 2015 04 junit-testing-exceptions-with-java-8 html

User · Answer

Use Mockito s doThrow and then catch the desired exception to assert it was thrown later    Test public void fooShouldThrowMyException            given     val myClass   new MyClass        val arg   mock MyArgument class       doThrow MyException class  when arg  argMethod any         Exception exception   null          when     try           myClass foo arg         catch  MyException t            exception   t                then     assertNotNull exception

User · Answer

If you want to test the exception message as well you can use JUnit s ExpectedException with Mockito    Rule public ExpectedException expectedException   ExpectedException none      Test public void testExceptionMessage   throws Exception       expectedException expect AnyException class       expectedException expectMessage  The expected message         given foo bar    willThrow new AnyException  The expected message

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I think this should do it for you  assertThrows someException class    - gt  mockedServiceReference someMethod param1 parme2

User · Answer

If you re using JUnit 4  and Mockito 1 10 x Annotate your test method with    Test expected   AnyException class    and to throw your desired exception use   Mockito doThrow new AnyException    when obj  callAnyMethod

User · Answer

Using mockito  you can make the exception happen   when testingClassObj testSomeMethod  thenThrow new CustomException      Using Junit5  you can assert exception  asserts whether that exception is thrown when testing method is invoked    Test  DisplayName  Test assert exception   void testCustomException TestInfo testInfo        final ExpectCustomException expectEx   new ExpectCustomException          InvalidParameterCountException exception   assertThrows InvalidParameterCountException class     - gt                expectEx constructErrorMessage  sample    error                    assertEquals  Invalid parametercount  expected 3  passed 2   exception getMessage         Find a sample here  assert exception junit

User · Answer

To answer your second question first  If you re using JUnit 4  you can annotate your test with    Test expected MyException class    to assert that an exception has occured  And to  mock  an exception with mockito  use  when myMock doSomething    thenThrow new MyException

User · Answer

Assert by exception message       try           MyAgent getNameByNode  d          catch  Exception e            Assert assertEquals  Failed to fetch data    e getMessage

User · Answer

Or if your exception is thrown from the constructor of a class     Rule public ExpectedException exception   ExpectedException none      Test public void myTest              exception expect MyException class       CustomClass myClass  mock CustomClass class       doThrow new MyException  constructor failed    when myClass

[java] Mockito How to mock and assert a thrown exception?

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