java - powermockito:如何模拟枚举中的抽象方法

Question

考虑以下(简化的)枚举:

MyEnum {
    ONE public int myMethod() {
        // Some complex stuff
        return 1;
    },

    TWO public int myMethod() {
        // Some complex stuff
        return 2;
    };

    public abstract int myMethod();
}

这用在如下函数中:

void consumer() {
    for (MyEnum n : MyEnum.values()) {
       n.myMethod();
    }
}

我现在想为consumer编写一个单元测试，模拟每个枚举实例中对 myMethod() 的调用。我尝试过以下方法:

@RunWith(PowerMockRunner.class)
@PrepareForTest(MyEnum.class)
public class MyTestClass {
    @Test
    public void test() throws Exception {
        mockStatic(MyEnum.class);

        when(MyEnum.ONE.myMethod()).thenReturn(10);
        when(MyEnum.TWO.myMethod()).thenReturn(20);

        // Now call consumer()
}

但是 ONE.myMethod() 和 TWO.myMethod() 的实际实现正在被调用。

我做错了什么？

Answer 1

1. 枚举中的每个常量都是一个静态最终嵌套类。因此，要模拟它，您必须在PrepareForTest 中指向嵌套类。
2. MyEnum.values() 返回预初始化的数组，因此在您的情况下它也应该是模拟的。
3. 每个枚举常量只是 public final static 字段。

一起:

@RunWith(PowerMockRunner.class)
@PrepareForTest(
value = MyEnum.class,
fullyQualifiedNames = {
                          "com.stackoverflow.q45414070.MyEnum$1",
                          "com.stackoverflow.q45414070.MyEnum$2"
})

public class MyTestClass {

  @Test
  public void should_return_sum_of_stubs() throws Exception {

    final MyEnum one = mock(MyEnum.ONE.getClass());
    final MyEnum two = mock(MyEnum.TWO.getClass());

    mockStatic(MyEnum.class);
    when(MyEnum.values()).thenReturn(new MyEnum[]{one, two});

    when(one.myMethod()).thenReturn(10);
    when(two.myMethod()).thenReturn(20);

    assertThat(new Consumer().consumer())
        .isEqualTo(30);
  }

  @Test
  public void should_return_stubs() {

    final MyEnum one = mock(MyEnum.ONE.getClass());

    when(one.myMethod()).thenReturn(10);

    Whitebox.setInternalState(MyEnum.class, "ONE", one);

    assertThat(MyEnum.ONE.myMethod()).isEqualTo(10);
  }

}

Full example