PowerMock单元测试

在Java程序的单元测试中常用的mock工具有Mockito和EasyMock。但是这两种mock工具都无法实现对静态、final、私有方法或类的mock。因此有了功能强大的PowerMock工具。PowerMock并不是一个独立、全新的工具而是在Mockito和EasyMock的基础上进行的扩展，它分别有针对Mockito级EasyMock的扩展实现。本文主要介绍PowerMock的常见用法：

1.pom依赖

<dependency>
	<groupId>junit</groupId>
	<artifactId>junit</artifactId>
        <version>4.10<version>
	<scope>test</scope>
</dependency>
<dependency>
        <groupId>org.powermock</groupId>
        <artifactId>powermock-module-junit4</artifactId>
        <version>1.6.3</version>
        <scope>test</scope>
</dependency>
<dependency>
        <groupId>org.powermock</groupId>
        <artifactId>powermock-api-mockito</artifactId>
        <version>1.6.3</version>
        <scope>test</scope>
</dependency>

 2.基本用法

2.1 测试类加上必要的注解

@RunWith(PowerMockRunner.class)
@PrepareForTest({ExtensionLoader.class,Configs.class})  //静态类，测试类本身（需要mock构造方法时）
@PowerMockIgnore("javax.management.*")

2.2 mock基本对象

测试 convert.convertAndHanlder(method,ref,bead)方法

@Mock
Convert convert;

when(convert.convertAndHanlder(eq(method),eq(ref),eq(bead))).thenReturn(bead);

2.3 mock无返回值的方法

@Mock
ProviderComposeConfig providerComposeConfig;

doNothing().when(providerComposeConfig).putSync(eq(providerConfig));

2.4 mock方法执行异常场景

@Mock
ProviderComposeConfig providerComposeConfig;

doThrow(new Exception("执行失败")).when(providerComposeConfig).putSync(eq(providerConfig));

2.5 mock 静态方法

测试Configs.getConfig（ProviderComposeConfig.class）方法

前提：@PrepareForTest注解中添加该类：ProviderComposeConfig.class

@Mock
ProviderComposeConfig configs;

PowerMockito.mockStatic(Configs.class);
when(Configs.getConfig(eq(ProviderComposeConfig.class))).thenReturn(configs);

mock无返回值的static方法

// "xxxUtil" 是类名
// "xxxStaticMethod" 是 static 方法的方法名
// 这里假设 "xxxStaticMethod" 需要两个参数，一个是 int 型，一个是 String 型
PowerMockito.doNothing().when(xxxUtil.class, "xxxStaticMethod", 1，"mysql");

mock可变参数传递

public class Demo {
	public static void test(String... args) {
		System.out.println(args);
	}
}

测试方法：

@RunWith(PowerMockRunner.class)
@PrepareForTest({Demo.class})
@PowerMockIgnore("javax.management.*")
public class DemoTest {

	@Test
	public void test() throws Exception {
		PowerMockito.mockStatic(Demo.class);
		PowerMockito.doNothing().when(Demo.class,"test",eq("liu1"),eq("liu2"));
		Demo.test("liu1","liu2");
	}

}

2.6 mock 构造方法

前提：@PrepareForTest注解中添加该类：HookContext.class

@Mock
HookContext context; 

//无参构造
PowerMockito.whenNew(HookContext.class).withNoArguments().thenReturn(context);

//有参构造
PowerMockito.whenNew(HookContext.class).withArguments(anystring()).thenReturn(context);

③完成实例

被测试类：

public class HandlerHook {

	public final static String id = "handler";

	@Override
	public Bead doCall(HookContext context, Bead bead, AccessId id) throws Throwable {
		ProviderComposeConfig configs = Configs.getConfig(ProviderComposeConfig.class);
		ProviderConfig config = configs == null ? null : configs.get(id);

		if (config == null) {
			// 即没有该服务，1.本地调用 2.客户端信息有误，访问IP:PORT 却没有服务
			return null;
		}

		// 拿到转换器，调用
		Convert convert = ExtensionLoader.getExtensionLoader(Convert.class).getExtensionById(ConvertProcessor.id);
		return convert.convertAndHanlder(config.getMethod(), config.getRef(), bead);
	}

}

测试类：

@RunWith(PowerMockRunner.class)
@PrepareForTest({ExtensionLoader.class,Configs.class})
@PowerMockIgnore("javax.management.*")
public class HandlerHookTest {

	@Mock
	HookContext hookContext;

	@Mock
	Bead bead;

	@Mock
	AccessId accessId;

	@Mock
	ExtensionLoader<Convert> extensionLoader;

	@Mock
	ProviderComposeConfig configs;

	@Mock
	ProviderConfig config;

	@Mock
	Method method ;

	@Mock
	Object ref;

	@Mock
	Convert convert;

	private HandlerHook handlerHook = new HandlerHook();

	@Test
	public void doCall() throws Throwable {
		PowerMockito.mockStatic(Configs.class);
		when(Configs.getConfig(eq(ProviderComposeConfig.class))).thenReturn(configs);
		when(configs.get(eq(accessId))).thenReturn(config);

		PowerMockito.mockStatic(ExtensionLoader.class);
		when(ExtensionLoader.getExtensionLoader(eq(Convert.class))).thenReturn(extensionLoader);
		when(extensionLoader.getExtensionById(eq("map"))).thenReturn(convert);
		when(config.getMethod()).thenReturn(method);
		when(config.getRef()).thenReturn(ref);

		when(convert.convertAndHanlder(eq(method),eq(ref),eq(bead))).thenReturn(bead);
		assertEquals(bead, handlerHook.doCall(hookContext, bead, accessId));
	}

}