getAnnotation(Class<T>) always returns null when I'm using EasyMock/PowerMock to mock java.lang.reflect.Method - junit

Question

The tested method has the following code:
SuppressWarnings suppressWarnings = method.getAnnotation(SuppressWarnings.class);
In my test method.I mocked java.lang.reflect.Method:
Method method= PowerMock.createMock(Method.class);
SuppressWarnings sw = EasyMock.createMock(SuppressWarnings.class);
EasyMock.expect(method.getAnnotation(SuppressWarnings.class)).andReturn(sw);
In the tested method,
method.getAnnotation(SuppressWarnings.class); always returns null.
I don't know why.Could anyone help me?
//code:
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.METHOD)
public #interface Anonymous {
}
public class AnnotationClass {
public Anonymous fun(Method m){
Anonymous anonymous = m.getAnnotation(Anonymous.class);
return anonymous;
}
}
// test class:
#RunWith(PowerMockRunner.class)
#PrepareForTest(Method.class)
public class AnnotationClassTest {
#Test
public void test() throws NoSuchMethodException, SecurityException {
AnnotationClass testClass = new AnnotationClass();
final Method mockMethod = PowerMock.createMock(Method.class);
final Anonymous mockAnot = EasyMock.createMock(Anonymous.class);
EasyMock.expect(mockMethod.getAnnotation(Anonymous.class)).andReturn(mockAnot);
PowerMock.replay(mockMethod);
final Anonymous act = testClass.fun(mockMethod);
Assert.assertEquals(mockAnot, act);
PowerMock.verify(mockMethod);
}
}
error:
java.lang.AssertionError: expected:<EasyMock for interface
com.unittest.easymock.start.Anonymous> but was:<null>

Answer 1

SuppressWarnings has #Retention(value=SOURCE) which means that it is not available at runtime:
public static final RetentionPolicy SOURCE: Annotations are to be discarded by the compiler.
However, if you would try your code with a different annotation that is available at runtime, method.getAnnotation(MyAnnotation.class) would still return null. That is, because by default the mocked Method will return null for method calls.
I think your problem is in the configuration of the mock, when I run your code (using an annotation that is available at runtime) I get the following exception:
Exception in thread "main" java.lang.IllegalStateException: no last call on a mock available
at org.easymock.EasyMock.getControlForLastCall(EasyMock.java:466)
at org.easymock.EasyMock.expect(EasyMock.java:444)
at MockStuff.main(MockStuff.java:54)
This page has some explanations about how to mock a final class (such as Method).
Your code gives the exact same result for me. I was able to get it working using the following code:
#RunWith(PowerMockRunner.class)
#PrepareForTest(Method.class)
public class AnnotationClassTest {
#Test
public void test() throws NoSuchMethodException, SecurityException {
final Method mockMethod = PowerMock.createMock(Method.class);
final Anot mockAnot = EasyMock.createMock(Anot.class);
EasyMock.expect(mockMethod.getAnnotation(Anot.class)).andReturn(mockAnot);
PowerMock.replay(mockMethod);
final Anot methodReturn = mockMethod.getAnnotation(Anot.class);
Assert.assertEquals(mockAnot, methodReturn);
}
}
#Retention(RetentionPolicy.RUNTIME)
#interface Anot {}
Note that this code is self contained, I defined the Anot interface since you didn't give the definition of Anonymous.