Here is the code I used:
// member of test class private MyWorker mockMyWorker = mock(MyWorker.class); private List<String> listOfOutputValues; private final String theValueIWant = "some test value";
The class I am testing will use a helper class named MyWorker in this example. The class being tested will call the method MyWorker.listOutputValues(SomeObject) to get a list of output values. The SomeObject has an attribute named someValue. I only want the MyWorker class to return the output listing if the someValue matches a specific value. I added a "when" statement in the @Before section of the test class. The "when" statement uses the custom matcher to check the value of SomeObject.getSomeValue().
@Before
private void Setup() {
listOfOutputValues = createTestOutputValues();
when(mockMyWorker.
listOutputValues(argThat(hasValidAttributeValue()))).
thenReturn(listOfOutputValues);
}
When the mockMyWorker.listOutputValues(SomeObject) method is called in the test code, then it will return the list of Strings if SomeObject.getSomeValue() equals theValueIWant. Here is how the custom matcher is defined in the test class:
// private method in test class
private Matcher<SomeObject> hasValidAttributeValue() {
return new BaseMatcher<SomeObject>() {
@Override
public boolean matches(Object o) {
return ((SomeObject)o).getSomeValue().equals(theValueIWant);
}
@Override
public void describeTo(Description description) {
}
};
}
