Mockito doNothing with Mockito.mockStatic

Question

I'm using Mockito, along with mockito-inline for mocking static methods. I'm trying to apply doNothing or similar behavior, to a static void method. The following workaround work, but I think that there should have a more convenient way to achieve this with less code.

try (MockedStatic<UtilCalss> mock = Mockito.mockStatic(UtilCalss.class)) {

     mock.when(() -> UtilCalss.staticMethod(any()))
            .thenAnswer((Answer<Void>) invocation -> null);

}

If it's a non-static method, we could simply do:

doNothing().when(mock).nonStaticMethod(any());

But I want to do the same for a static method.

Answer 1

You don't need to stub that call.

doNothing is a default behaviour of a void method called on a mock.

Example:

Class under test:

public class UtilClass {
    public static void staticMethod(String data) {
        System.out.println("staticMethod called: " + data);
    }
}

Test code:

public class UtilClassTest {
    @Test
    void testMockStaticForVoidStaticMethods() {
        try (MockedStatic<UtilClass> mockStatic = Mockito.mockStatic(UtilClass.class)) {
            UtilClass.staticMethod("inMockStaticScope");
        }
        UtilClass.staticMethod("outOfMockStaticScope");
    }
}

Output:

staticMethod called: outOfMockStaticScope