Using PowerMockito.whenNew() is not getting mocked and original method is called

Question

I have a code somewhat like this below:

Class A {
  public boolean myMethod(someargs) {
    MyQueryClass query = new MyQueryClass();
    Long id = query.getNextId();
    // some more code
  }
}
Class MyQueryClass     {
  ....
  public Long getNextId() {
    //lot of DB code, execute some DB query
    return id;
  }
}

Now I'am writing a test for A.myMethod(someargs) . I want to skip the real method query.getNextId() and instead return a stub value. Basically, I want to mock MyQueryClass .

So in my test case, I have used:

MyQueryClass query = PowerMockito.mock(MyQueryClass.class);
PowerMockito.whenNew(MyQueryClass.class).withNoArguments().thenReturn(query);
when(query.getNextId()).thenReturn(1000000L);

boolean b = A.getInstance().myMethod(args);

//asserts

I used @RunWith(PowerMockRunner.class) and @PrepareForTest({MyQueryClass.class}) in the beginning of my test class.

But when I debug the test, it is still calling the real method getNextId() of the MyQueryClass class.

What am I missing here? Can anyone help as I am new to Mockito and PowerMockito.

Answer 1

You need to put the class where the constructor is called into the @PrepareForTest annotation instead of the class which is being constructed - see Mock construction of new objects .

In your case:

✗ @PrepareForTest(MyQueryClass.class)

✓ @PrepareForTest(A.class)

More general:

✗ @PrepareForTest(NewInstanceClass.class)

✓ @PrepareForTest(ClassThatCreatesTheNewInstance.class)

Answer 2

As @TrueDub mentioned in his accepted reply, you need to add the class where the constructor is called to the @PrepareForTest .

However, if you do this, coverage for that class as reported by eclemma and Sonar will be zero for that class

Powermockito wiki

We are going to replace Javassist with ByteBuddy (#727) and it should help to resolve this old issue. But right now there is NO WAY TO USE PowerMock with JaCoCo On-the-fly instrumentation. And no workaround to get code coverage in IDE.

So the solution here would be to refactor the actual code to use a static factory that would return an instance of that class and then statically mock it.

Answer 3

It also doesn't work with method reference. For example PowerMockito can't mock new instance for TargetClass here:

TargetClass target = Optional.ofNullable( x )
                                     .map( TargetClass::new )
                                     .orElse( null );

Answer 4

也许你可以简单地使用

Mockito.doReturn(value).when(xxx)