During suite tests EasyMock says 0 matchers expected 1 recorded

Question

So I've been using EasyMock's class extension for a while now. All of a sudden I'm getting this exception, but only when I run the entire test suite:

java.lang.IllegalStateException: 0 matchers expected, 1 recorded.
at org.easymock.internal.ExpectedInvocation.createMissingMatchers(ExpectedInvocation.java:42)
at org.easymock.internal.ExpectedInvocation.<init>(ExpectedInvocation.java:34)
at org.easymock.internal.ExpectedInvocation.<init>(ExpectedInvocation.java:26)
at org.easymock.internal.RecordState.invoke(RecordState.java:64)
at org.easymock.internal.MockInvocationHandler.invoke(MockInvocationHandler.java:24)
at org.easymock.internal.ObjectMethodsFilter.invoke(ObjectMethodsFilter.java:56)
at org.easymock.classextension.internal.ClassProxyFactory$1.intercept(ClassProxyFactory.java:74)
at com.protrade.soccersim.data.emulator.matrix.PositionCategoryMatrix$$EnhancerByCGLIB$$c5298a7.getPossession(<generated>)
at com.protrade.soccersim.data.emulator.stats.team.PossessionCalculatorUnitTest.testDeterminePossessionHomeWin(PossessionCalculatorUnitTest.java:45)

The code involved is this little beauty (trimmed a bit):

    @Before
public void setUp() throws Exception {
    homeTeam = createMock( PositionCategoryMatrix.class );
    awayTeam = createMock( PositionCategoryMatrix.class );
    ...
}

@Test
public void testDeterminePossessionHomeWin() {
    expect(homeTeam.getPossession()).andReturn( 0.15151515 );
    expect(awayTeam.getPossession()).andReturn( 0.01515152 );
    replay( homeTeam, awayTeam );
    ...
}

The exception is being thrown on the first expect. And it really doesn't make sense. It says it's getting a matcher, but the method doesn't even take an argument. And odd enough it's only during test suites! I'm creating a new mock in the @Before, so it shouldn't be inheriting anything from somewhere else (not that some other method would have a matcher on it)

So, any ideas?

Answer 1

I am running into a similar problem. From what I observed, even method returns are matched using Matchers. So if you first method fails for any reason, the matcher for the return match is still in the stack. That could be one reason why you are seeing 1 matchers recorded even when your method doesn't take any argument. Basically, the first method invocation never returned a value.

Answer 2

Which version of Easymock are you using?
I read a post about the release of v.2.5.2 and previuous versions might have a

dumb bug on the capture

try to use Easymock 2.5.2+

Answer 3

While it's true that this can be a spurious message resulting from a "silly" EasyMock bug, it is also very likely to be due to invalid usage of the EasyMock API. In my case the message arose from this JUnit 3.8 test (and like you, this only happened when I ran my entire suite of tests, and only via Maven, not Eclipse):

public void testSomething() {
    // Set up
    MyArgumentType mockArg = (MyArgumentType) EasyMock.anyObject(); // bad API usage

    // Invoke the method under test
    final String result = objectUnderTest.doSomething(mockArg);

    // Verify (assertions, etc.)
    ...
}

Instead of using anyObject(), I should have used createMock(MyArgumentType.class) or one of its variants. I don't know what I was thinking, I've written millions of these tests and used the API correctly.

The confusing bit is that the test that fails with the "wrong number of matchers" message isn't necessarily (or ever?) the one in which you used the API wrongly. It might be the first test executed after the buggy one that contains a replay() or verify() method, but I haven't verified this experimentally.

Answer 4

I had the same error message. I was (accidentally) using an isA() declaration in the call on the class under test

I.e.

classUnderTest.callStateChanged(calls, isA(LoggingOnlyListener.class));

when I meant:

classUnderTest.callStateChanged(calls, new LoggingOnlyListener());

And it was the test AFTER this one that failed every time.