如何使用 PowerMockito 模拟构造函数

I'm trying to mock a class constructor with PowerMockito for first time, but it doesn't work. My current code is:

public class Bar {
    public String getText() {
        return "Fail";
    }
}

public class Foo {
    public String getValue(){
        Bar bar= new Bar();
        return bar.getText();
    }

}

@RunWith(PowerMockRunner.class)
@PrepareForTest(Bar.class)
public class FooTest {
    private Foo foo;
    @Mock
    private Bar mockBar;

    @Before
    public void setUp() throws Exception {
        MockitoAnnotations.initMocks(this);
        PowerMockito.whenNew(Bar.class).withNoArguments().thenReturn(mockBar);
        foo= new Foo();
    }

    @Test
    public void testGetValue() throws Exception {
        when(mockBar.getText()).thenReturn("Success");
        assertEquals("Success",foo.getValue());

    }
}

测试失败，因为返回值为Fail".我的问题在哪里?

@PrepareForTest(Foo.class)

@PrepareForTest(Bar.class)