使用Powermock和mockito测试静态方法

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        实例：

package com.bijian.study;

import static org.junit.Assert.assertEquals;

import java.io.IOException;

import org.junit.Before;
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;

class MyStringUtil {   
	  
    public static String uppercase(String s) {   
        return s.toUpperCase();   
    }   
}   

//1.标注使用PowerRunner运行test（powermock会修改字节码） 
@RunWith(PowerMockRunner.class)

//2.设置mock类（支持多个类，逗号分隔），这个可以设置到class上，也可以设置到method上
//这里面包含两种类型： 
//a.被mock的类（如上例MyStringUtil .class，如果mock类为系统类，如System.class，则不需要这里设置就可以使用）
//b.context类，如果是在XxxServer里面希望mock MyStringUtil类，则要设置 XxxServer.class
@PrepareForTest({ MyStringUtil.class })  
public class HelloTest {   
  
    @Before  
    public void before() {
    	//3.告诉powermock需要mock哪个类
        PowerMockito.mockStatic(MyStringUtil.class);  
    }   
  
    @Test  
    public void test() throws IOException {
    	//4.打桩，设置mock对象返回预期值
        PowerMockito.when(MyStringUtil.uppercase("abc")).thenReturn("ABC");
        
        //5.执行mock方法，返回预期值
        assertEquals("ABC", MyStringUtil.uppercase("abc"));   
    }   
}

        注意：如上代码引入javassist-3.4.GA.jar、junit-4.9.0.jar、mockito-all-1.9.0.jar、powermock-mockito-1.4.12-full.jar能正常运行。

 

        附：如使用Powermock和mockito测试静态方法时，如运行单元测试报”NoClassDefFoundError: javassist/util/proxy/MethodFilter“错误，详细如下所示：

java.lang.NoClassDefFoundError: javassist/expr/ExprEditor
	at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.createNewClassloader(AbstractTestSuiteChunkerImpl.java:196)
	at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.chunkClass(AbstractTestSuiteChunkerImpl.java:170)
	at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.(AbstractTestSuiteChunkerImpl.java:92)
	at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.(AbstractTestSuiteChunkerImpl.java:85)
	at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.(JUnit4TestSuiteChunkerImpl.java:47)
	at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.(AbstractCommonPowerMockRunner.java:32)
	at org.powermock.modules.junit4.PowerMockRunner.(PowerMockRunner.java:31)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(Unknown Source)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(Unknown Source)
	at java.lang.reflect.Constructor.newInstance(Unknown Source)
	at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:31)
	at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:24)
	at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
	at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:29)
	at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
	at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:24)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.(JUnit4TestReference.java:33)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.(JUnit4TestClassReference.java:25)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:48)
	at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:38)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.ClassNotFoundException: javassist.expr.ExprEditor
	at java.net.URLClassLoader$1.run(Unknown Source)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.net.URLClassLoader.findClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	at sun.misc.Launcher$AppClassLoader.loadClass(Unknown Source)
	at java.lang.ClassLoader.loadClass(Unknown Source)
	... 25 more

 解决方法：引入javassist-3.4.GA.jar