模拟受保护的方法 [英] mocking protected method

问题描述

我想模拟一个继承的受保护方法.我不能直接从java代码调用这个方法，因为它是从另一个包中的类继承的.我找不到在 when(...)

I want to mock an inherited protected method. I can't call this method directly from java code as it is inherited from class that in another package. I can't find a way to specify this method to stub in in when(...)

package a;

public class A() {
    protected int m() {}
}

package b;

public class B extends a.A {
    // this class currently does not override m method from a.A
    public asd() {}
}

// test
package b;

class BTest {
    @Test
    public void testClass() {
        B instance = PowerMockito.spy(new B());
        PowerMockito.when(instance, <specify a method m>).thenReturn(123);
        //PowerMockito.when(instance.m()).thenReturn(123); -- obviously does not work
    }
}

我查看了 PowerMockito.when 覆盖，这似乎都只用于私有方法！

I looked at PowerMockito.when overrides and this seems that they are all for private methods only!

如何指定受保护的方法?

How to specify protected method?

推荐答案

简而言之:不能总是使用 when 来存根间谍；使用 doReturn.

Nutshell: Can't always use when to stub spies; use doReturn.

假设 spy 和 doReturn(都是 PowerMockito)的静态导入:

Assuming static imports of spy and doReturn (both PowerMockito):

@RunWith(PowerMockRunner.class)
@PrepareForTest(B.class)
public class BTest {
    @Test public void testClass() throws Exception {
        B b = spy(new B());
        doReturn(42).when(b, "m");
        b.asd();
    }
}

您也可以@PrepareForTest(A.class) 并在when(a, "m") 上设置doReturn.哪个更有意义取决于实际测试.

You could also @PrepareForTest(A.class) and set up the doReturn on when(a, "m"). Which makes more sense depends on the actual test.

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