Problem verifying bridge methods

[fbaro]

Hello, I think there might be a bug in mockito when verifying bridge methods.
The bug is present both in version 2.0.31-beta, and in version 1.10.19.

import java.io.Serializable;
import org.junit.Test;
import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.verify;

public class MockitoBridgeTest {

    @Test
    public void test() {
        Extended ext = mock(Extended.class);
        ext.test("123");
        verify(ext).test("123"); // Passes
        ((Base<String>)ext).test("456");
        verify(ext).test("456"); // Fails
    }

    public interface Base<T extends Serializable> {
        int test(T value);
    }

    public interface Extended extends Base<String> {
        @Override
        int test(String value);
    }

}

[raphw]

The problem here is the following: Byte Buddy does not intercept bridge methods but assumes that these methods should be dispatched as they are. Therefore, the actual method is still invoked which is then intercepted. As a result, the Method instance that is bound to this interception is the actual method, i.e. test(String) and not test(Serializable) which was identified as the bridge. The behavior of cglib is similar.

Mockito on the other hand picks up the invoked method from the call site which is test(Serializable) fpr the secod example. Therefore, Mockito claims that another method is invoked. Instead, Mockito would need to resolve the method to its actual target in order to validate that this method is a bridge for test(String).

I am going to look into how this can be added to Mockito. This requires resolving parameterized tyes along the hierarchy in order to find out to what method the bridge is actually pointing to.

[fbaro]

Since somebody else has this issue, I found a workaround to make the test pass:

        ((Base<String>)ext).test("456");
        verify(ext).test("456"); // Fails
        ((Base<String>)verify(ext)).test("456"); // Passes (workaround)

[raphw]

@bric3 Would it be a feasible solution if I relied on Byte Buddy APIs to resolve this? I implemented a rather elaborate algorithm that I have tried to port to Mockito. However, its not as easy as I thought since the algorithm and related data structure are quite bound into the Byte Buddy APIs. I would of course add an interface that does not rely on Byte Buddy for querying this information but asking the library to do it would be the most straight-forward solution.

[bric3]

@raphw That is possible, maybe in the form of a Plugin that ByteBuddy mockmaker implement, maybe we would need a default implementation, i.e. that does nothing.