使用 Mockito 控制方法输出

Question

假设我有一个 class 这样的：

public class RegularStuff {

    public int getAmountOfStuff() {

        int stuff = getAmount();
        return stuff;
    }

    public int getAmount() {
        return 10;
    }
}

现在假设我有一个这样的单元测试：

@RunWith(PowerMockRunner.class)
public class StuffTest {

    private RegularStuff testobject;

    @Before
    public void setUp() {
        testObject = new RegularStuff();
    }

    @Test
    public void testGetAmountOfStuff() {
        int result = testObject.getAmountOfStuff();
        assertEquals(5, result);
    }
}

请注意，上述说法是无效的。它会失败，因为方法 getAmountOfStuff 调用另一个总是 returns 10 的方法。我将它们分开以使代码更易于分析。给出这个例子可能看起来微不足道，但我经常发现自己创建了更大的方法。因此，我在给定函数中拆分了代码。否则，大量的文本变得太多 big/confusing 无法分析或修复 - 更不用说测试了。

所以我需要知道的是如何控制我正在测试的class中某些方法的输出。

Answer 1

1) mock一个public方法，下面是测试方法。

@RunWith(PowerMockRunner.class)
public class StuffTest {

private RegularStuff testObject;

@Before
public void setUp() {
    testObject = PowerMockito.mock(RegularStuff.class, Mockito.CALLS_REAL_METHODS);
    // The reason using CALLS_REAL_METHODS is that we are both testing & mocking same object.
}

// test by mocking public method
@Test
public void testGetAmountOfStuff() {

    PowerMockito.when(testObject.getAmount()).thenReturn(5);

    int result = testObject.getAmountOfStuff();
    Assert.assertEquals(5, result);
}

}

2) 如果你的getAmount()是私有方法，下面是模拟私有方法的测试方法。

@RunWith(PowerMockRunner.class)
@PrepareForTest(RegularStuff.class)
public class StuffTest {

private RegularStuff testObject;

@Before
public void setUp() {
    testObject = PowerMockito.mock(RegularStuff.class, Mockito.CALLS_REAL_METHODS);
    // reason using CALLS_REAL_METHODS, we are both testing & mocking same object.
}

// test by mocking private method
@Test
public void testByMockingPrivateMethod() throws Exception{

    PowerMockito.doReturn(5).when(testObject , "getAmount" );
    int result = testObject.getAmountOfStuff();
    Assert.assertEquals(5, result);
 }
}

使用 Mockito 控制方法输出

Controlling method output with Mockito

java

methods

unit-testing

mocking

powermockito