PowerMock学习笔记（二）

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PowerMock结合EasyMock

一、Mock静态方法
1、快速总结：
1）在测试用例类级使用@RunWith(PowerMockRunner.class)注释
2）在测试用例类级使用@PrepareForTest(ClassThatContainsStaticMethod.class)
3）使用PowerMock.mockStatic(ClassThatContainsStaticMethod.class)mock这个类的所有方法
4）使用PowerMock.replay(ClassThatContainsStaticMethod.class)切换至replay模式
5）使用PowerMock.verify(ClassThatContainsStaticMethod.class)切换至验证模式

2、例子
        假设存在如下类ServiceRegistrator：
public class ServiceRegistrator {
        public long registerService(Object service) {
                final long id = IdGenerator.generateNewId();
                serviceRegistrations.put(id, service);
                return id;
        }
}
        ServiceRegistrator引用了IdGenerator中的静态方法，为了测试registerService方法，我们需要mock IdGenerator.generateNewId()。
IdGenerator实现如下：
public class IdGenerator {

        /**
        * @return A new ID based on the current time.
        */
        public static long generateNewId() {
                  return System.currentTimeMillis();
        }

}

        要mock IdGenerator我们在类级使用@PrepareForTest(IdGenerator.class）来注释，并且告诉JUnit使用PowerMock：@RunWith(PowerMockRunner.class)
这两个注释是必须的，没有的话测试会失败。
package com.larry.junit;

import org.easymock.EasyMock;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.powermock.api.easymock.PowerMock;
import org.powermock.core.classloader.annotations.PrepareForTest;
import org.powermock.modules.junit4.PowerMockRunner;

@RunWith(PowerMockRunner.class)

@PrepareForTest({IdGenerator.class})

public class ServiceRegistratorTest {

@Test

public void testRegistService() {

Long expectId = 12L;
ServiceRegistrator test = new ServiceRegistrator();
//mock
PowerMock.mockStatic(IdGenerator.class);
//expect
EasyMock.expect(IdGenerator.generateNewId()).andReturn(expectId);
//replay
PowerMock.replay(IdGenerator.class);
Long actualId = test.registerService(new Object());
//verify
PowerMock.verify(IdGenerator.class);
org.junit.Assert.assertEquals(expectId, actualId);

}

}