Powermock在最终void方法上意外引发InvalidUseOfMatchersException

Question

我正在对我的Java应用程序进行单元测试。。

我的目标是使用Powermock在BOProcessor类的实例上创建一个间谍。BOProcessor拥有最终作废方法；我将设置spy，以便在调用此方法时引发异常。在这个测试中，我还将模拟MyDao，但模拟这个类很简单。然后，模拟的MyDao将被传递到名为classUnderTest的MyDaoService实例中。然后，我将针对classUnderTest做出断言。

每当我尝试设置上述场景时，Powermock（或Mockito？）在我的间谍上设置doThrow时会抛出InvalidUseOfMatchersException。奇怪的是，只有当doThrow期望后跟一个对class UnderTest的调用时，才会抛出此异常。如果我删除稍后调用的class UnderTest，则预期工作正常。更奇怪的是——class UnderTest甚至不使用抛出错误的间谍！

这是我上面概述的全部测试代码。为了突出问题，我删除了所有不直接相关的代码。（我甚至取消了这次测试的全部目的。）

package my.package;

import static org.mockito.Matchers.any;
import static org.mockito.Mockito.doThrow;
import static org.powermock.api.mockito.PowerMockito.mock;
import static org.powermock.api.mockito.PowerMockito.spy;

import org.junit.Test;

public class WhatAmIDoingWrong {

    @Test
    public void whatAmIDoingWrong() {

        MyDao mockedDao = mock(MyDao.class);
        BOProcessor processor = new BOProcessor();
        BOProcessor mockedProcessor = spy(processor);

        MyDaoService classUnderTest = new MyDaoService(mockedDao);

        doThrow(new Exception()).when(mockedProcessor).process(any(FakeBusinessObject.class));

        classUnderTest.interactWithDao();
    }
}

这是从我的测试代码的doThrow行抛出的异常（讽刺的是），我正试图解决它。

org.mockito.exceptions.misusing.InvalidUseOfMatchersException: 
Invalid use of argument matchers!
0 matchers expected, 1 recorded:
-> at my.package.WhatAmIDoingWrong.whatAmIDoingWrong(WhatAmIDoingWrong.java:21)

This exception may occur if matchers are combined with raw values:
    //incorrect:
    someMethod(anyObject(), "raw String");
When using matchers, all arguments have to be provided by matchers.
For example:
    //correct:
    someMethod(anyObject(), eq("String by matcher"));

For more info see javadoc for Matchers class.

    at my.package.MyDaoService.interactWithDao(MyDaoService.java:33)
    at my.package.WhatAmIDoingWrong.whatAmIDoingWrong(WhatAmIDoingWrong.java:23)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:89)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:41)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:541)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:763)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:463)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:209)

这是我的测试使用的类。重申一下，名为class UnderTest的MyDaoService甚至不知道BOProczer的间谍；它只对MyDao的模拟有效。但是只有调用了类UnderTest，对BOProczer间谍的期望才会失败。

public class BOProcessor {

    public final void process(FakeBusinessObject bar) {}
}

public class FakeBusinessObject {

}

import java.util.Collections;
import java.util.List;

public class MyDao {

    public MyDao() {}

    public List<String> getAllData(){
        return Collections.emptyList();
    }

}

public class MyDaoService {

    private MyDao applicationDao;

    public MyDaoService(MyDao applicationDao) {
        this.applicationDao = applicationDao;
    }

    public synchronized void interactWithDao() {
        applicationDao.getAllData();
    }
}

我使用的是JUnit 4.12、Mockito 1.10.19和Powermock 1.7.4。该项目正在运行Spring 4.3.12版本，包括Spring测试。

为什么Powermock会引发此异常？我是否未正确使用任何匹配器？究竟为什么只有当稍后的调用与不同的模拟交互时才会引发此异常？

谢谢你的帮助！

Answer 1

原来我用间谍是错误的。组织中的某些东西。莫基托。存根。斯塔伯。当（T mock）被实现时，意味着我不能以我想要的方式对间谍设定期望。但无论如何，捕获实际上更适合我的用例。

最后，我的测试是这样的：

public class FixedNow{

    @Test
    public void fixedNow() {

        MyDao mockedDao = mock(MyDao.class);
        BOProcessor mockedProcessor = mock(BOProcessor.class);
        FakeBusinessObject problematicBO = new FakeBusinessObject();
        ArgumentCaptor<FakeBusinessObject> fakeBOCaptor = ArgumentCaptor.forClass(FakeBusinessObject.class);

        MyDaoService classUnderTest = new MyDaoService(mockedDao, mockedProcessor);

        doThrow(new Exception()).when(mockedProcessor).process(eq(problematicBO));
        doNothing().when(mockedProcessor).process(fakeBOCaptor.capture());

        classUnderTest.interactWithDao();

        assertThings(BOCaptor.getValue());
    }
}

谢谢你的想法！