Mockito和PowerMock用法

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参考技术A

​ PowerMock是Java开发中的一种Mock框架，用于 单元模块测试 。当你想要测试一个service接口，但service需要经过防火墙访问，防火墙不能为你打开或者你需要认证才能访问。遇到这样情况时，你可以在你能访问的地方使用MockService替代，模拟实现获取数据。

​ PowerMock可以实现完成对 private/static/fina l方法的Mock（模拟），而Mockito可以对普通的方法进行Mock，如：public等。

Demo演示

PowerMock基于Mockito开发，起语法规则与Mockito一致，主要区别在于使用方面，以实现完成对 private/static/fina l等方法(也支持mock的对象是在方法内部new出来的)的Mock（模拟）。具体事例如下：

1、添加依赖

我们可以使用Mockito和PowerMock出售junit测试类

我有一个只有一个method的java类，在我创建object for another class的方法中，所以我使用的是PowerMockito.whenNew(fullyQualifiedClassName).withAnyArguments().thenReturn(mockObject);。在同样的方法中，我必须模拟另一个method(non-static)所以我必须在这里使用Mockito像Mockito.when(mockObject.method1(1000)).thenReturn(createdObject);//showing error here。我收到的错误如下

org.mockito.exceptions.misusing.UnfinishedStubbingException: 
Unfinished stubbing detected here:
-> at com.tocassandra.DMCassandraTest.test(DMCassandraTest.java:38)

E.g. thenReturn() may be missing.
Examples of correct stubbing:
when(mock.isOk()).thenReturn(true);
when(mock.isOk()).thenThrow(exception);
doThrow(exception).when(mock).someVoidMethod();
Hints:
 1. missing thenReturn()
 2. you are trying to stub a final method, you naughty developer!
 3: you are stubbing the behaviour of another mock inside before         'thenReturn' instruction if completed

at com.tocassandra.DMCassandraTest.test(DMCassandraTest.java:75)
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.junit.internal.runners.TestMethod.invoke(TestMethod.java:68)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:326)
at org.junit.internal.runners.MethodRoadie$2.run(MethodRoadie.java:88)
at org.junit.internal.runners.MethodRoadie.runBeforesThenTestThenAfters(MethodRoadie.java:96)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.executeTest(PowerMockJUnit44RunnerDelegateImpl.java:310)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTestInSuper(PowerMockJUnit47RunnerDelegateImpl.java:131)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.access$100(PowerMockJUnit47RunnerDelegateImpl.java:59)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner$TestExecutorStatement.evaluate(PowerMockJUnit47RunnerDelegateImpl.java:147)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.evaluateStatement(PowerMockJUnit47RunnerDelegateImpl.java:107)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit47RunnerDelegateImpl$PowerMockJUnit47MethodRunner.executeTest(PowerMockJUnit47RunnerDelegateImpl.java:82)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$PowerMockJUnit44MethodRunner.runBeforesThenTestThenAfters(PowerMockJUnit44RunnerDelegateImpl.java:298)
at org.junit.internal.runners.MethodRoadie.runTest(MethodRoadie.java:86)
at org.junit.internal.runners.MethodRoadie.run(MethodRoadie.java:49)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.invokeTestMethod(PowerMockJUnit44RunnerDelegateImpl.java:218)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.runMethods(PowerMockJUnit44RunnerDelegateImpl.java:160)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl$1.run(PowerMockJUnit44RunnerDelegateImpl.java:134)
at org.junit.internal.runners.ClassRoadie.runUnprotected(ClassRoadie.java:33)
at org.junit.internal.runners.ClassRoadie.runProtected(ClassRoadie.java:45)
at org.powermock.modules.junit4.internal.impl.PowerMockJUnit44RunnerDelegateImpl.run(PowerMockJUnit44RunnerDelegateImpl.java:136)
at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:117)
at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:57)
at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:59)
at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:86)
at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:459)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:678)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:382)
at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:192)

我用注释宣布Junit Test class

@RunWith(PowerMockRunner.class) @PrepareForTest({NewObjectClass.class})

示例代码： -

原始方法如下所示

public static void insertData(String name) throws Exception {

    ObjectMapper mapper = new ObjectMapper();
    SampleA sample = new SampleA("args1","arg2",4);

    sample.subscribe(name); //its a void method
    logger.info("subscibed to the topic {}", ConsumerTopicName);
    cluster = Cluster.builder().addContactPoints(CASSANDRA_CONNECTION_HOST.split(",")).build();
    session = cluster.connect(KEYSPACE);

    try {

        while (true) {
            try {
                SampleRecords records = sample.getRecords("argValue");
                for (Record record : records) {

                    A a = mapper.readValue(record.value(), A.class);

                    dao.insertData(session, a);
                }
            } catch (Exception ex) {
                logger.error("Exception while reading data from kafka", ex);
            }
        }
    } finally {
        consumer.close();
    }
}

测试类： - 

@RunWith(PowerMockRunner.class)
@PrepareForTest({SampleA.class})
public class DMCassandraTest {

SampleA sample = Mockito.mock(SampleA.class);
@Test
public void test() throws Exception{
    String name = "test";
    PowerMockito.whenNew("org.companny.SampleA").withAnyArguments().thenReturn(sample);
    Mockito.doAnswer(new Answer(){

        @Override
        public Object answer(InvocationOnMock invocation) throws Throwable {
            sample.subscribe(name);
            return null;
        }

    }).when(SampleA.class);
    // Above code is to mock void subscribe method in insertData, even I am 
    // not sure whther it works or not
    SampleRecords records = new SampleReccords();
    // setting values to records
    Mockito.when(sample.getRecords("argdValue")).thenReturn(records);
    insertToCassandra.insertData(name);
}
}
答案

主要问题是这个块：

Mockito.doAnswer(new Answer(){

    @Override
    public Object answer(InvocationOnMock invocation) throws Throwable {
        sample.subscribe(name);
        return null;
    }

}).when(SampleA.class);

Mockito问你，“什么时候？”您没有指定Mockito的模拟应该回复的时间。从逻辑上看，似乎你想在subscribe之后这样做。

但是，说实话，我没有看到很多机会（或理由）嘲笑。您获得的实例具体定义，无法轻松注入以增加其值的差异。我的建议是不要嘲笑这些，直到你可以在某处注入SampleA，这样添加模拟比依赖PowerMockito更麻烦。

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