Introducing the Ability to Mock Construction of Generic Types #2401
Description
First of all, thank you for building an awesome testing library!
I have recently started playing with mocked object construction. It's fantastic that this functionality is now available through plain ol' Mockito. It makes for some pretty elegant tests, especially when combined with @Mock using the MockitoExtension.
One limitation I've encountered is around mocking the constructions of parameterized types.
Here's what I'd like to accomplish:
@ExtendWith(MockitoExtension.class)
class DefaultKafkaConsumerTest {
@Mock
private MockedConstruction<KafkaConsumer<String, String>> kafkaConsumerMockedConstruction;
@Test
void testMyThing() {
new DefaultKafkaConsumer<String, String>();
final KafkaConsumer<String, String> mockConsumer = kafkaConsumerMockedConstruction.constructed().get(0);
// ... assert
}
Unfortunately, this doesn't seem to work, as indicated by this message:
Mockito cannot infer a static mock from a raw type for kafkaConsumerMockedConstruction
Instead of @Mock MockedConstruction you need to specify a parameterized type
For example, if you would like to mock Sample.class, specify
@Mock MockedConstruction<Sample>
as the type parameter. If the type is itself parameterized, it should be specified as raw type.
As suggested, I've updated my tests as follows:
@ExtendWith(MockitoExtension.class)
class DefaultKafkaConsumerTest {
@Mock
private MockedConstruction<KafkaConsumer> kafkaConsumerMockedConstruction;
@Test
void testMyThing() {
new DefaultKafkaConsumer<String, String>();
@SuppressWarnings("unchecked")
final KafkaConsumer<String, String> mockConsumer = kafkaConsumerMockedConstruction.constructed().get(0);
// ... assert
}
I'm less fond of suppressing warnings everywhere. I've extracted the unchecked operation into a helper method, but I think that just covers up the problem.
I'm curious to understand the technical reason why the MockedConstruction generic parameter has to be a raw type. It's interesting that I can create generic mocks and argument captors, but I can't do this through mocked construction.
Thanks for your time!