看起来正确的doThrow中的Mockito异常

Question

I'm trying to mock a method to see if I handle an exception correctly. This is as far as I get.

interface:

interface SampleManager {
    void deleteVariome(String specimenId, String analysisId) throws Exception;
    // ...
}

unit test:

// ...
SampleManger sampleManager = mock(SampleManager.class);

// below is line 753
doThrow(Exception.class).when(sampleManager).deleteVariome(sample1.getId(), analysisId);

result:

org.mockito.exceptions.misusing.UnfinishedStubbingException: 
Unfinished stubbing detected here:
-> at ...server.ArchiveManagerImplUTest.deleteVariomeFails(ArchiveManagerImplUTest.java:753)

E.g. thenReturn() may be missing.
Examples of correct stubbing:
    when(mock.isOk()).thenReturn(true);
    when(mock.isOk()).thenThrow(exception);
    doThrow(exception).when(mock).someVoidMethod(); <-- this looks a log like what I did!

Hints:

 1. missing thenReturn()

 2. you are trying to stub a final method, you naughty developer! <-- I have a lot of other mocks of this interface in this test that work.

Answer 1

From an identical issue that I just ran into, I suspect that sample is a mock, and you stubbed sample.getId() elsewhere? That caused this problem in my case, anyhow.

For some reason, Mockito gets upset if one of the arguments you pass to the stub used with doThrow in this way is the result of a method you also mocked. Perhaps it's a re-entrancy check of sorts to avoid infinite loops, I don't know.

Regardless, try replacing sample.getId() with a constant value and that should solve the issue. You could consider using a constant declared in your test for both the mock and any further uses of it. You could then also check that sample.getId() was used by the method you're testing by adding another call to verify .

Answer 2

This error is usually reported AFTER the place where it actually occurred. If you fail to stub something properly, Mockito usually can't tell until the NEXT time you call one of the Mockito methods. This might be in the same test method, a later test method in the same class, or even an entirely different test class.

The line that you've quoted looks fine to me. Take a look at the lines above it, where you call a Mockito stubbing or verification method. It's very likely that you have a when that has no associated thenReturn , then or thenThrow . Or you might have a verify that's missing the actual method call. There are a few other possibilities too.

If you can't find an error in the lines ABOVE the one that you've quoted, then post some more of your code, and I'll take a closer look.

Answer 3

As described in the answer by Gijs, this is probably due to a bug in Mockito. Here is a complete test which reproduces it:

interface Sample { String getId(); }
interface SampleManager {
    void deleteVariome(String specimenId, String analysisId);
}

@Test
public void probableMockitoBug() {
    Sample sample1 = mock(Sample.class);
    when(sample1.getId()).thenReturn("a");

    SampleManager manager = mock(SampleManager.class);
    doThrow(Exception.class).when(manager).deleteVariome(sample1.getId(), "b");

    manager.deleteVariome("a", "b");
}

The test produces the following output:

org.mockito.exceptions.misusing.UnfinishedStubbingException: 
Unfinished stubbing detected here:
-> at org.mockitousage.JavadocExamplesTest.probableMockitoBug(JavadocExamplesTest.java:404)

E.g. thenReturn() may be missing.
Examples of correct stubbing:
    when(mock.isOk()).thenReturn(true);
    when(mock.isOk()).thenThrow(exception);
    doThrow(exception).when(mock).someVoidMethod();
Hints:
 1. missing thenReturn()
 2. you are trying to stub a final method, you naughty developer!

    at org.mockito.exceptions.Reporter.unfinishedStubbing(Reporter.java:55)
    at org.mockito.internal.progress.MockingProgressImpl.validateState(MockingProgressImpl.java:74)
    at org.mockito.internal.progress.ThreadSafeMockingProgress.validateState(ThreadSafeMockingProgress.java:49)
    at org.mockito.internal.MockHandler.handle(MockHandler.java:71)
    at org.mockito.internal.InvocationNotifierHandler.handle(InvocationNotifierHandler.java:36)
    at org.mockito.internal.creation.MethodInterceptorFilter.intercept(MethodInterceptorFilter.java:48)
    at org.mockitousage.JavadocExamplesTest$Sample$$EnhancerByMockitoWithCGLIB$$d5ac41.getId()
    at org.mockitousage.JavadocExamplesTest.probableMockitoBug(JavadocExamplesTest.java:404)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
    at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)

Answer 4

you have to supply an instance of the Exception.class not the Exception class itself.

doThrow(new Exception()).when(sampleManager).deleteVariome(sample1.getId(), analysisId);

EDIT Well @DavidWallace corrected me, so be warned (or rather enlightened) that since 1.9 you can just provide the exception class to throw and it will construct one for you.