Null Pointer Exception in mocking Interface method

问题:

I'm using TestNG for testing and JMockit for mocking mockMethod(). Here's the test case:

@Test public void testClass1() {     new MockUp<MyInterface>() {     @Mock     public int myMethod(final MyObject someObject ){          return 0;         }     };      MyObject obj = new MyObject();     Assert.assertEquals(obj.mockMethod(someObject),0);      } }

The mockMethod() I'm calling for assertEquals() looks like this:

public class Class1 {       MyInterface my;       public int mockMethod(final MyObject someObject ){              ......  //processing steps              return my.myMethod(someObject);       } }

Test case throws a Null pointer exception. What am I doing wrong? Do I mock the implementation of mockMethod()? I tried that too, but it hasn't worked.

回答1:

JMockit created a mock instance of MyInterface, but your test never used it. It can be obtained through the MockUp#getInstance() method. Then of course the test also needs to pass the instance to the class under test.

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