AnyString() as parameter for unit test

java junit mockito powermock assertj
user4063815 picture user4063815 · Sep 9, 2016 · Viewed 42.6k times · Source

I have to deal with a legacy application that has no tests. So before I begin refactoring I want to make sure everything works as it is.

Now imagine the following situation:

public SomeObject doSomething(final OtherObject x, final String something) {
    if(x == null) throw new RuntimeException("x may not be null!");
    ...
}

Now I want to test that null check, so to be sure it works and I don't lose it once I refactor.

So I did this

@Test(expected = RuntimeException.class)
public void ifOtherObjectIsNullExpectRuntimeException() {
    myTestObject.doSomething(null, "testString");
}

Now, this works of course.

But instead of "testString" I'd like to pass in a random String.

So I tried with:

@Test(expected = RuntimeException.class)
public void ifOtherObjectIsNullExpectRuntimeException() {
    myTestObject.doSomething(null, Mockito.anyString());
}

But this is not allowed., as I get

org.mockito.exceptions.misusing.InvalidUseOfMatchersException: ... You cannot use argument matchers outside of verifications or stubbing

I do understand the meaning of this, but I wonder whether I can still manage to do what I want without parameterizing my test or the like. The only libraries I may use are Junit, AssertJ, Mockito and Powermock.

Any ideas?

Answer

Code-Apprentice picture Code-Apprentice · Sep 9, 2016

Tests should be deterministic. Using random values in a test makes it difficult to reproduce behavior when debuging a failed test. I suggest that you just create a String constant for the test such as "abcdefg".

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