Mocking whenNew using withAnyArguments does not match null arguments

[sgilhooly]

Using:

• powermock-module-junit4 2.0.0-beta.5
• powermock-api-mockito2 2.0.0-beta.5
• mockito-core 2.16.0

I am having trouble using the whenNew(Class).withAnyArguments() when one of those arguments is null in the tested code. For example, the following test case is failing for me:

package org.mypackage;

import org.apache.http.HttpResponse;
import org.apache.http.ReasonPhraseCatalog;
import org.apache.http.StatusLine;
import org.apache.http.message.BasicHttpResponse;
import org.junit.Assert;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

import static org.mockito.Mockito.mock;
import static org.powermock.api.mockito.PowerMockito.whenNew;

@RunWith(PowerMockRunner.class)
@PrepareForTest({BasicHttpResponse.class})
public class TestNullArgument {

    @Test
    public void testReproduce() throws Exception {

        final BasicHttpResponse testResponse = mock(BasicHttpResponse.class);
        whenNew(BasicHttpResponse.class).withAnyArguments().thenReturn(testResponse);

        // Note the 3rd argument 'null' which I expect would match when using 'withAnyArgument'
        HttpResponse r = new BasicHttpResponse(mock(StatusLine.class), mock(ReasonPhraseCatalog.class), null);

        Assert.assertNotNull("The newly allocated (mocked) value should not be null", r);
    }
}

This test example should pass but because the withAnyArguments() generates incorrect constructor argument matchers, the new returns null and the assertion fails.

I have tried to examine this under the debugger and I am able to determine that the the "expected" matches are getting generated as: [any(StatusLine.class), any(ReasonPhraseCatalog.class), any(Locale.class)] which causes it to not match the third null parameter, since null is not instanceof(Locale.class).

I'm having a hard time figuring out where it generated the list of argument matchers though to find the bug.

[sgilhooly]

For what it's worth I reproduced this problem with the latest HEAD of branch release/2.x (version 2.0.0-beta.8).

When an object has multiple constructors, this code in withAnyArguments generates matchers for the first constructor and matchers for the remaining constructors are generated somewhere else (during the thenReturn flow somewhere I haven't found yet). The first constructor's matchers are generated properly (using the form or(isA(Class), isNull())). But the remaining constructors are not (they only have any(Class) which causes them to not match against nullvalues).

So if the constructor you need mocked happens to be the first one the withAnyArguments code picks up, then the test will work. But it's easy to get unlucky and get stuck with a different constructor which has the incorrect matchers.