Mockito如何mock靜態(tài)方法

在實(shí)際工作當(dāng)中，我們經(jīng)常會(huì)遇到需要對(duì)靜態(tài)方法進(jìn)行 mock 的情況。在 mockito 2.x 的時(shí)代，我們需要借助 powmock 才能實(shí)現(xiàn)。

當(dāng) mockito 進(jìn)化到了 3.4.0 版本以后，也開(kāi)始對(duì)靜態(tài)方法 mock 進(jìn)行了支持（主要是通過(guò) mockito-inline 包）。

簡(jiǎn)單的介紹就到這里，下面讓我們進(jìn)入主題吧。

1.首先確保pom文件中

mockito 相關(guān) jar 包的版本（這里我用的版本是 3.7.7），如下：

<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-core</artifactId>
    <version>3.7.7</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-inline</artifactId>
    <version>3.7.7</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-junit-jupiter</artifactId>
    <version>3.7.7</version>
    <scope>test</scope>
</dependency>
<dependency>
     <groupId>junit</groupId>
     <artifactId>junit</artifactId>
     <version>4.13</version>
     <scope>test</scope>
 </dependency>

2.使用方式

Mockito.mockStatic(Class mockClass)，如下：

// 這里 DateUtil 內(nèi)提供了靜態(tài)方法
MockedStatic<DateUtil> dateUtil = mockStatic(DateUtil.class);

示例：

import static org.mockito.Mockito.mockStatic;

@RunWith(MockitoJUnitRunner.class)
public class AlphaServiceTest {

    @Test
    public void testHttp() {
        ...
        
        MockedStatic<HTTPClient> httpClient = mockStatic(HTTPClient.class);
        httpClient.when(() -> HTTPClient.sendPost("xxx/zzz/ccc", "hello")).thenReturn("success");
        
        ...
        
        // 關(guān)閉
        httpClient.close();
    }
    

這樣基本上就 OK 了。

唯一需要注意下的就是 httpClient.close()，這個(gè)問(wèn)題會(huì)在「3.其他」中 “錯(cuò)誤提示 static mocking is already registered in the current thread To create a new mock, the existing static mock registration must be deregistered” 進(jìn)行詳細(xì)說(shuō)明）

3.其他

如果項(xiàng)目中未引入 mockito-inline，會(huì)出現(xiàn)如下錯(cuò)誤信息：

org.mockito.exceptions.base.MockitoException: 
The used MockMaker SubclassByteBuddyMockMaker does not support the creation of static mocks

Mockito's inline mock maker supports static mocks based on the Instrumentation API.
You can simply enable this mock mode, by placing the 'mockito-inline' artifact where you are currently using 'mockito-core'.
Note that Mockito's inline mock maker is not supported on Android.

    at com.annoroad.order.service.PreOrderServiceTestCase.testSaveClinicalFreeSuccess1(PreOrderServiceTestCase.java:86)
    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.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.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
    at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
    at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
    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$2.evaluate(ParentRunner.java:268)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:33)
    at com.intellij.rt.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:230)
    at com.intellij.rt.junit.JUnitStarter.main(JUnitStarter.java:58)

錯(cuò)誤提示

static mocking is already registered in the current thread To create a new mock, the existing static mock registration must be deregistered

當(dāng)多個(gè)單元測(cè)試都使用了同一個(gè) static mock 對(duì)象，且使用完成后都沒(méi)有進(jìn)行 close。此時(shí)，若這幾個(gè)單元測(cè)試用一起執(zhí)行，第一個(gè)單元測(cè)試占用了 static mock 對(duì)象，第二個(gè)單元測(cè)試就沒(méi)有辦法再占用了。

如果出現(xiàn)了這種情況，解決辦法也很簡(jiǎn)單，就是關(guān)閉 static mock 對(duì)象，如下：

import static org.mockito.Mockito.mockStatic;

@RunWith(MockitoJUnitRunner.class)
public class AlphaServiceTest {

    @Test
    public void testHttp1() {
        ...
        
        MockedStatic<HTTPClient> httpClient = mockStatic(HTTPClient.class);
        httpClient.when(() -> HTTPClient.sendPost("xxx/zzz/ccc", "hello")).thenReturn("success");
        
        ...

		httpClient.close();
    }
    
    @Test
    public void testHttp2() {
        ...
        
        MockedStatic<HTTPClient> httpClient = mockStatic(HTTPClient.class);
        httpClient.when(() -> HTTPClient.sendPost("xxx/zzz/ccc", "hello")).thenReturn("success");
        
        ...

		httpClient.close();
    }
    
    @Test
    public void testHttp3() {
        ...
        
        MockedStatic<HTTPClient> httpClient = mockStatic(HTTPClient.class);
        httpClient.when(() -> HTTPClient.sendPost("xxx/zzz/ccc", "hello")).thenReturn("success");
        
        ...
		
		httpClient.close();
    }

如果你的很多單元測(cè)試中都用到了 mockStatic(HTTPClient.class)，且覺(jué)得在每個(gè)單元測(cè)試當(dāng)中都寫(xiě)一遍 mockStatic()…close() 很低效，可以采用下邊的方式：

import static org.mockito.Mockito.mockStatic;

@RunWith(MockitoJUnitRunner.class)
public class AlphaServiceTest {
	private MockedStatic<HttpClietn> httpClient;

	// 每個(gè)單元測(cè)試啟動(dòng)前，先執(zhí)行該方法（高版本中 @Before 被替換成 @BeforeEach）
    @Before
    public void setUp() {
        this.httpClient = mockStatic(HTTPClient.class);
    }
    
	// 每個(gè)單元測(cè)試執(zhí)行完成后，執(zhí)行該方法（高版本中 @After 被替換成 @AfterEach）
    @After
    public void teardown() {
        this.httpClient.close();
    }

    @Test
    public void testHttp1() {
        ...
        
        httpClient.when(() -> HTTPClient.sendPost("xxx/zzz/ccc", "hello")).thenReturn("success");
        
        ...
    }
    
    @Test
    public void testHttp2() {
        ...
        
        httpClient.when(() -> HTTPClient.sendPost("xxx/zzz/ccc", "hello")).thenReturn("success");
        
        ...
    }
    
    @Test
    public void testHttp3() {
        ...
        
        httpClient.when(() -> HTTPClient.sendPost("xxx/zzz/ccc", "hello")).thenReturn("success");
        
        ...
    }

這樣就清爽多了 ~：）

總結(jié)

以上為個(gè)人經(jīng)驗(yàn)，希望能給大家一個(gè)參考，也希望大家多多支持腳本之家。

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