MockUp<T> getMockInstance return null

[russelyang]

import mockit.Mock; import mockit.MockUp; import mockit.Mocked; import org.junit.Test;

import javax.servlet.ServletOutputStream;

import static org.junit.Assert.assertNotNull;

/**

• Created by ruyang on 7/23/2014. */ public class Playgroud {

  class A { private void doNothing() {} public void doSomething(int i) {} }

  @Test public void mockServletOutputStream() { ServletOutputStream stream = new MockUp() { @Mock public void $clinit() { /* do nothing */ } @Mock public void $init() {}

  }.getMockInstance();
  
  assertNotNull(stream);

  }

  @Test public void doSomething() { A a = new MockUp() { @Mock void doNothing() {} }.getMockInstance(); assertNotNull(a); } }

my assertions are failing, checked 1.9 source code, it seems caused by private T redefineClassOrImplementInterface(@NotNull Class classToMock, @Nullable Type typeToMock) { if (classToMock.isInterface()) { return new MockedImplementationClass(this).generate(classToMock, typeToMock); }

  classesToRestore = redefineMethods(classToMock, typeToMock);
  return null;

}

it should return mocked object, not null.

Please note the API documentation for MockUp#getInstance() says it always returns null when the mocked type is a class.

[russelyang]

But how can I get an object of the class? ServletOutputStream is an abstract class, I have no way to grab an object instance? Did I miss something?

I am really need MockUp and verify the http response content.

For concrete class , it is kind of make sense, but Abstract class should be treated the same way as Interface. updated sample

public class Playgroud {

abstract class A {
    private void doNothing() {}
    public void doSomething(int i) {}
}

@Test
public void doSomething() {
    A a = new MockUp<A>() {
        @Mock void doNothing() {}
    }.getMockInstance();
    assertNotNull(a);
}

}

[rliesenfeld]

Yes, MockUp doesn't have the ability to generate a subclass for an abstract class. The @Mocked/Expectations API does, though. You can obtain an abstract class instance by declaring a mock field or mock parameter of the abstract class type.

[russelyang]

Although @mocked Expectations can generate mock instance, like ServletOutputStream case, what I need is a state testing, I want to check what write in the servletOutputStream is correct. Thank you for you time reply the question, I create a FakeServerOutputStream extend ServletOutputStream work around this case.