How to mock querydsl query? - unit-testing

Question

In my prod code I have the following queryDsl query:
Collection<String> myList = new ArrayList<>();
myList.add("blue");
myList.add("green");
myList.add("yellow");
QAnimal qAnimal = QAnimal.animal;
return animalRepository.exists(
qAnimal.color.in(myList).and(
qAnimal.name.eq("animal_name")
)
);
I want to mock this queryDsl query using Mockito. In my test file, in the setup method I did:
Collection<Book> myList = new ArrayList<>();
myList.add("blue");
myList.add("green");
myList.add("yellow");
QAnimal qAnimal = QAnimal.animal;
when(qAnimal.color.in(myList)).thenReturn((Expressions.asBoolean(false)));
when(qAnimal.name.eq("animal_name")).thenReturn((Expressions.asBoolean(true)));
When running the test, I receive the following problem:
org.mockito.exceptions.misusing.MissingMethodInvocationException:
when() requires an argument which has to be 'a method call on a mock'.
For example:
when(mock.getArticles()).thenReturn(articles);
Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
Those methods *cannot* be stubbed/verified.
2. inside when() you don't call method on mock but on some other object.
I can't create a JPAQuery object, only use that kind of queries.

Answer 1

Why would you mock JPAQuery? At this point you're either testing the internals of Querydsl, or making sure that you wrote what you wrote. Just mock the entire AnimalRepository instead. And if you want to test animalRepository properly, its best to do so in an integration test that actually executes the query against a database. There is also the possibility to execute the query against mock data using querydsl-collections.
If you insist on mocking JPAQuery with Mockito stubs however, the easiest way to mock builder API's, like for example JPAQuery, is to use Answers.RETURNS_SELF as default stub.
For example, use the following to instantiate your queryMock:
#Mock(answer = Answers.RETURNS_SELF) JPAQuery queryMock;