Powermockito Spy Private Void 方法调用

Question

对于使用私有 void 方法的测试类，模拟方法行为的正确方法是什么？下面的解决方案改为调用该方法。

public class TestWizard {
private void testOne(){
throw new NullPointerException();
}
private void testTwo(){
testOne();
}
}
@RunWith(PowerMockRunner.class)
@PrepareForTest({TestWizard.class})
public class WTest {
@Test
public void testWizard() throws Exception {
TestWizard wizard2 = Whitebox.newInstance(TestWizard.class);
TestWizard wizard = Mockito.spy(wizard2);
PowerMockito.doNothing().when(wizard, "testTwo");
}
}

错误是：

java.lang.NullPointerException
at tuk.pos.wizard.model.TestWizard.testOne(TestWizard.java:6)
at tuk.pos.wizard.model.TestWizard.testTwo(TestWizard.java:10)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.powermock.reflect.internal.WhiteboxImpl.performMethodInvocation(WhiteboxImpl.java:1862)
at org.powermock.reflect.internal.WhiteboxImpl.doInvokeMethod(WhiteboxImpl.java:824)
at org.powermock.reflect.internal.WhiteboxImpl.invokeMethod(WhiteboxImpl.java:689)
at org.powermock.reflect.Whitebox.invokeMethod(Whitebox.java:401)
at org.powermock.api.mockito.internal.expectation.PowerMockitoStubberImpl.when(PowerMockitoStubberImpl.java:105)

Answer 1

使用PowerMockito.spy(...)而不是Mockito.spy(...)。

使用 PowerMockito2.0.5进行测试

import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.mockito.PowerMockito;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;
import org.powermock.reflect.Whitebox;
@RunWith(PowerMockRunner.class)
@PrepareForTest(WTest.TestWizard.class)
public class WTest {
public class TestWizard {
private void testOne(){
throw new NullPointerException();
}
private void testTwo(){
testOne();
}
}
@Test
public void testWizard() throws Exception {
TestWizard spy = PowerMockito.spy(Whitebox.newInstance(TestWizard.class));
PowerMockito.doNothing().when(spy, "testTwo");
spy.testTwo();
}
}

---

尝试将spies的使用限制为旧代码。在大多数其他情况下，重构应该是首选解决方案。