<p>单元测试由一组独立的测试构成，每个测试针对软件中的一个单独的程序单元。单元测试并非检查程序单元之间是否能够合作良好，而是检查单个程序单元行为是否正确。</p>    <h2>为什么要进行单元测试</h2>    <p>在敏捷开发大行其道的今天，由于时间紧，任务重，过分依赖测试工程师以及下列原因，导致单元测试不被重视，在开发流程中处于一个可有可无的尴尬境地。</p>    <ol>     <li>浪费的时间太多</li>     <li>软件开发人员不应参与单元测试</li>     <li>我是很棒的程序员，不需要进行单元测试</li>     <li>不管怎样，集成测试将会抓住所有的Bug</li>     <li>单元测试效率不高</li>    </ol>    <p>那么单元测试是否正的可有可无呢？No! No! No!</p>    <ol>     <li>作为android客户端研发，在一个开发周期内，你负责的需求需要Web服务（API），和本地代码（JNI，Native Code）的支持，而你们的工作是同时进行的。</li>     <li>你的需求开发完成了，但是由于需要在特定条件下才能触发，而这些条件在开发过程中很难去模拟，导致需求无法在所有场景下进行充分测试。举个例子，假设你在室内开发一个地图导航的Android应用，你需要在导航过程中，前方出现车祸，积水，施工等多种状况，怎么办？</li>     <li>总结你过去的BUG，你会发现有些你以为写的很完善的逻辑，却在最后被发现有场景未覆盖，或者逻辑错误等问题。</li>     <li>测试工程师给你报了一个BUG，你改完提交了，但是之后由于Merge失误导致代码丢失，或者其他人的修改导致你的BUG再次出现。直到测试工程师再次发现该BUG，并再次给你提出。</li>     <li>你的开发进度很快，但是开发完成后，你会被BUG淹没。你持续不断的修改BUG，持续不断的加班，直至发布版本，身心俱疲。</li>     <li>以前明明很正常的功能，在本次开发周期内，突然不能正常使用了。<br> …</li>    </ol>    <p>如果你也经常碰到以上问题，或者困扰，那么你需要持续不断的对项目进行 <strong>单元测试</strong> 。</p>    <h2>Android单元测试简介</h2>    <p>Android的单元测试分为两大类：</p>    <p>1.Instrumentation</p>    <p>通过Android系统的Instrumentation测试框架，我们可以编写测试代码，并且打包成APK，运行在Android手机上。</p>    <p>优点： 逼真</p>    <p>缺点： 很慢</p>    <p>代表框架：JUnit(Android自带),espresso</p>    <p>2.JUnit / Mock</p>    <p>通过JUnit，以及第三方测试框架，我们可以编写测试代码，生成class文件，直接运行在JVM虚拟机中。</p>    <p>优点： 很快。使用简单，方便。</p>    <p>缺点： 不够逼真。比如有些硬件相关的问题，无法通过这些测试出来。</p>    <p>代表框架： JUnit(标准),Robolectric, mockito, powermock</p>    <h2>Android最佳Mock单元测试方案</h2>    <p>我通过对比前辈们对各种单元测试框架的实践，总结出Android最佳Mock单元测试方案: Junit + Mockito + Powermock.（自己认证的…）</p>    <h3>Junit + Mockito + Powermock 简介</h3>    <p>众所周知，Junit是一个简单的单元测试框架。</p>    <p>Mockito，则是一个简单的用于Mock的单元测试框架。</p>    <p>那么为什么还需要Powermock呢？</p>    <p>EasyMock和Mockito等框架，对static, final, private方法均是不能mock的。</p>    <p>这些框架普遍是通过创建Proxy的方式来实现的mock。 而PowerMock是使用CGLib来操纵字节码而实现的mock，所以它能实现对上面方法的mock。</p>    <h3>Junit + Mockito + Powermock 引入</h3>    <p>由于PowerMock对Mockito有较强依赖，因此需要按照以下表格采用对应的版本。</p>    <table>     <thead>      <tr>       <th>Mockito</th>       <th>PowerMock</th>      </tr>     </thead>     <tbody>      <tr>       <td>2.0.0-beta - 2.0.42-beta</td>       <td>1.6.5+</td>      </tr>      <tr>       <td>1.10.8 - 1.10.x</td>       <td>1.6.2+</td>      </tr>      <tr>       <td>1.9.5-rc1 - 1.9.5</td>       <td>1.5.0 - 1.5.6</td>      </tr>      <tr>       <td>1.9.0-rc1 & 1.9.0</td>       <td>1.4.10 - 1.4.12</td>      </tr>      <tr>       <td>1.8.5</td>       <td>1.3.9 - 1.4.9</td>      </tr>      <tr>       <td>1.8.4</td>       <td>1.3.7 & 1.3.8</td>      </tr>      <tr>       <td>1.8.3</td>       <td>1.3.6</td>      </tr>      <tr>       <td>1.8.1 & 1.8.2</td>       <td>1.3.5</td>      </tr>      <tr>       <td>1.8</td>       <td>1.3</td>      </tr>      <tr>       <td>1.7</td>       <td>1.2.5</td>      </tr>     </tbody>    </table>    <p>建议方案：</p>    <p>在项目依赖文件build.gradle中添加以下依赖。</p>    <pre>  <code class="language-java">testCompile 'junit:junit:4.11'  // required if you want to use Mockito for unit tests  testCompile 'org.mockito:mockito-core:1.9.5'  // required if you want to use Powermock for unit tests  testCompile 'org.powermock:powermock-module-junit4:1.5.6'  testCompile 'org.powermock:powermock-module-junit4-rule:1.5.6'  testCompile 'org.powermock:powermock-api-mockito:1.5.6'  </code></pre>    <h3>Junit + Mockito + Powermock 配置</h3>    <ol>     <li>默认的测试代码位置<br> 对于通过gradle构建的android项目，在默认的项目结构中，Instrumentation的测试代码放在<br> src/androidTest/ 目录，而JUnit / Mock的测试代码放在 src/test/ 目录。</li>     <li>自定义测试代码位置<br> 有些项目是由Eclipse构建迁移到由Gradle构建，需要自定义测试代码位置。<br> 举个例子，androidTest和test目录都在项目的根文件夹下。我们需要这样配置： <pre>  <code class="language-java">android {    sourceSets {   test {   java.srcDir 'test'   }   androidTest {   java.srcDir 'androidTest'   }   }  }  </code></pre> </li>    </ol>    <p>如果在单元测试中遇到类似”Method … not mocked.”的问题，请添加以下设置：</p>    <pre>  <code class="language-java">android {  // ...   testOptions {    unitTests.returnDefaultValues = true   }  }  </code></pre>    <h3>Junit + Mockito + Powermock 使用</h3>    <p>强烈建议你熟读以下内容，来熟悉Junit + Mockito + Powermock的使用。</p>    <ol>     <li><a href="/misc/goto?guid=4959676264307677030" rel="nofollow,noindex">Mockito 中文文档 ( 2.0.26 beta )</a></li>     <li><a href="/misc/goto?guid=4959676264396028452" rel="nofollow,noindex">Mockito reference documentation</a></li>     <li><a href="/misc/goto?guid=4959676264476574721" rel="nofollow,noindex">powermock wiki</a></li>     <li><a href="/misc/goto?guid=4959672183663539269" rel="nofollow,noindex">Unit tests with Mockito - Tutorial</a></li>    </ol>    <p>下面通过举例来简单说明Junit + Mockito + Powermock 使用，更多详情清参考Demo项目：</p>    <p><a href="/misc/goto?guid=4959676264596101104" rel="nofollow,noindex">https://github.com/snowdream/test/tree/master/android/test/mocktest</a></p>    <p>源码： <a href="/misc/goto?guid=4959676264680859177" rel="nofollow,noindex">https://github.com/snowdream/test/blob/master/android/test/mocktest/app/src/main/java/snowdream/github/com/mocktest/Calc.java</a></p>    <p>测试代码： <a href="/misc/goto?guid=4959676264761276671" rel="nofollow,noindex">https://github.com/snowdream/test/blob/master/android/test/mocktest/app/src/test/java/snowdream/github/com/mocktest/CalcUnitTest.java</a></p>    <p>1.验证某些行为,主要是验证某些函数是否被调用，以及被调用的具体次数。</p>    <pre>  <code class="language-java">//using mock  mockedList.add("once");    mockedList.add("twice");  mockedList.add("twice");    mockedList.add("three times");  mockedList.add("three times");  mockedList.add("three times");    //following two verifications work exactly the same - times(1) is used by default  // 下面的两个验证函数效果一样,因为verify默认验证的就是times(1)  verify(mockedList).add("once");  verify(mockedList, times(1)).add("once");    //exact number of invocations verification  // 验证具体的执行次数  verify(mockedList, times(2)).add("twice");  verify(mockedList, times(3)).add("three times");    //verification using never(). never() is an alias to times(0)  // 使用never()进行验证,never相当于times(0)  verify(mockedList, never()).add("never happened");    //verification using atLeast()/atMost()  // 使用atLeast()/atMost()  verify(mockedList, atLeastOnce()).add("three times");  verify(mockedList, atLeast(2)).add("five times");  verify(mockedList, atMost(5)).add("three times");  </code></pre>    <p>2.验证执行顺序，主要验证某些函数是否按照预定顺序执行。</p>    <pre>  <code class="language-java">// A. Single mock whose methods must be invoked in a particular order  // A. 验证mock一个对象的函数执行顺序  List singleMock = mock(List.class);    //using a single mock  singleMock.add("was added first");  singleMock.add("was added second");    //create an inOrder verifier for a single mock  // 为该mock对象创建一个inOrder对象  InOrder inOrder = inOrder(singleMock);    //following will make sure that add is first called with "was added first, then with "was added second"  // 确保add函数首先执行的是add("was added first"),然后才是add("was added second")  inOrder.verify(singleMock).add("was added first");  inOrder.verify(singleMock).add("was added second");    // B. Multiple mocks that must be used in a particular order  // B .验证多个mock对象的函数执行顺序  List firstMock = mock(List.class);  List secondMock = mock(List.class);    //using mocks  firstMock.add("was called first");  secondMock.add("was called second");    //create inOrder object passing any mocks that need to be verified in order  // 为这两个Mock对象创建inOrder对象  InOrder inOrder = inOrder(firstMock, secondMock);    //following will make sure that firstMock was called before secondMock  // 验证它们的执行顺序  inOrder.verify(firstMock).add("was called first");  inOrder.verify(secondMock).add("was called second");    // Oh, and A + B can be mixed together at will  </code></pre>    <p>3.使用powermock必须使用两个annotation：</p>    <pre>  <code class="language-java">@RunWith(PowerMockRunner.class)  @PrepareForTest({Calc.class})  publicclassCalcUnitTest{  }  //PrepareForTest 后面要加准备被mock或stub的类，单个class直接()起来即可，多个用{}，并用逗号隔开。  </code></pre>    <p>4.测试公开成员变量</p>    <pre>  <code class="language-java">@Test  publicvoidtestPublicField(){   assertEquals(mCalc.mPublicField, 0);   assertEquals(mCalc.mPublicFinalField, 0);   assertEquals(Calc.mPublicStaticField, 0);   assertEquals(Calc.mPublicStaticFinalField, 0);     mCalc.mPublicField = 1;   Calc.mPublicStaticField = 2;     assertEquals(mCalc.mPublicField, 1);   assertEquals(mCalc.mPublicFinalField, 0);   assertEquals(Calc.mPublicStaticField, 2);  }  </code></pre>    <p>5.测试公开成员方法</p>    <pre>  <code class="language-java">@Test  publicvoidtestAddPublicMethod(){  //when   when(mCalc.addPublic(anyInt(), anyInt()))   .thenReturn(0)   .thenReturn(1)   .thenReturn(2)   .thenReturn(3)   .thenReturn(4)   .thenReturn(5);    //call method  for(inti =0; i <6; i++) {    //verify   assertEquals(mCalc.addPublic(i, i), i);   }    //verify   verify(mCalc, times(6)).addPublic(anyInt(), anyInt());   verify(mCalc, atLeast(1)).addPublic(anyInt(), anyInt());   verify(mCalc, atLeastOnce()).addPublic(anyInt(), anyInt());   verify(mCalc, atMost(6)).addPublic(anyInt(), anyInt());  }  </code></pre>    <p>6.测试公开无返回值成员方法</p>    <pre>  <code class="language-java">@Test  publicvoidtestAddPublicVoidMethod(){  //when   doNothing().when(mCalc).voidPublic(anyInt(), anyInt());     mCalc.voidPublic(anyInt(), anyInt());   mCalc.voidPublic(anyInt(), anyInt());     verify(mCalc, atLeastOnce()).voidPublic(anyInt(), anyInt());   verify(mCalc, atLeast(2)).voidPublic(anyInt(), anyInt());  }  </code></pre>    <p>7.测试公开静态成员方法</p>    <pre>  <code class="language-java">@Test  publicvoidtestAddPublicStaicMethod()throwsException{   PowerMockito.mockStatic(Calc.class);     PowerMockito.when(Calc.class, "addPublicStatic", anyInt(), anyInt())   .thenReturn(0)   .thenReturn(1)   .thenReturn(2)   .thenReturn(3)   .thenReturn(4)   .thenReturn(5);      //call method  for(inti =0; i <6; i++) {    //verify   assertEquals(Calc.addPublicStatic(i, i), i);   }      //verify static   PowerMockito.verifyStatic(times(6));  }  </code></pre>    <p>8.测试私有成员变量</p>    <p>Powermock提供了一个Whitebox的class，可以方便的绕开权限限制，可以get/set private属性，实现注入。也可以调用private方法。也可以处理static的属性/方法，根据不同需求选择不同参数的方法即可。</p>    <pre>  <code class="language-java">@Test  publicvoidtestPrivateField()throwsIllegalAccessException{   PowerMockito.mockStatic(Calc.class);     assertEquals(Whitebox.getField(Calc.class, "mPrivateField").getInt(mCalc),0);   assertEquals(Whitebox.getField(Calc.class, "mPrivateFinalField").getInt(mCalc),0);   assertEquals(Whitebox.getField(Calc.class, "mPrivateStaticField").getInt(null),0);   assertEquals(Whitebox.getField(Calc.class, "mPrivateStaticFinalField").getInt(null),0);       Whitebox.setInternalState(mCalc, "mPrivateField",1);   Whitebox.setInternalState(Calc.class, "mPrivateStaticField",1, Calc.class);     assertEquals(Whitebox.getField(Calc.class, "mPrivateField").getInt(mCalc),1);   assertEquals(Whitebox.getField(Calc.class, "mPrivateFinalField").getInt(mCalc),0);   assertEquals(Whitebox.getField(Calc.class, "mPrivateStaticField").getInt(null),1);   assertEquals(Whitebox.getField(Calc.class, "mPrivateStaticFinalField").getInt(null),0);  }  </code></pre>    <p>9.测试私有成员方法</p>    <pre>  <code class="language-java">@Test  publicvoidtestAddPrivateMethod()throwsException{   PowerMockito.mockStatic(Calc.class);    //when   PowerMockito.when(mCalc,"addPrivate",anyInt(),anyInt())   .thenReturn(0)   .thenReturn(1)   .thenReturn(2)   .thenReturn(3)   .thenReturn(4)   .thenReturn(5);    //call method  for(inti =0; i <6; i++) {    //verify   assertEquals(Whitebox.invokeMethod(mCalc,"addPrivate",i,i), i);   }    //verify static   PowerMockito.verifyPrivate(mCalc,times(6)).invoke("addPrivate",anyInt(),anyInt());   PowerMockito.verifyPrivate(mCalc,atLeast(1)).invoke("addPrivate",anyInt(),anyInt());   }  </code></pre>    <p>10.测试私有静态成员方法</p>    <pre>  <code class="language-java">@Test  publicvoidtestAddPrivateStaicMethod()throwsException{   PowerMockito.mockStatic(Calc.class);     PowerMockito.when(Calc.class, "addPrivateStatic", anyInt(), anyInt())   .thenReturn(0)   .thenReturn(1)   .thenReturn(2)   .thenReturn(3)   .thenReturn(4)   .thenReturn(5);      //call method  for(inti =0; i <6; i++) {    //verify   assertEquals(Whitebox.invokeMethod(Calc.class,"addPrivateStatic",i, i), i);   }      //verify static   PowerMockito.verifyStatic(times(6));   }  </code></pre>    <p>通过以上介绍，相信你对Android项目的Mock单元测试有一定的了解。</p>    <p>如果你有任何相关疑问，请通过以下方式联系我：</p>    <p>Email：yanghui1986527#gmail.com</p>    <p>QQ 群: 529327615</p>    <h2>参考</h2>    <ol>     <li><a href="/misc/goto?guid=4959676264851317224" rel="nofollow,noindex">详细讲解单元测试的内容</a></li>     <li><a href="/misc/goto?guid=4959676264929066098" rel="nofollow,noindex">浅谈单元测试的意义</a></li>     <li><a href="/misc/goto?guid=4959676265019963993" rel="nofollow,noindex">敏捷开发之测试</a></li>     <li><a href="/misc/goto?guid=4958865751774418439" rel="nofollow,noindex">Unit testing support</a></li>     <li><a href="/misc/goto?guid=4959670563914923239" rel="nofollow,noindex">junit4</a></li>     <li><a href="/misc/goto?guid=4958864743859781664" rel="nofollow,noindex">mockito</a></li>     <li><a href="/misc/goto?guid=4959646068745187412" rel="nofollow,noindex">powermock</a></li>     <li><a href="/misc/goto?guid=4959676264596101104" rel="nofollow,noindex">mocktest</a></li>     <li><a href="/misc/goto?guid=4959676265227047944" rel="nofollow,noindex">在Android Studio中进行单元测试和UI测试</a></li>     <li><a href="/misc/goto?guid=4959676265309176667" rel="nofollow,noindex">whats-the-best-mock-framework-for-java</a></li>     <li><a href="/misc/goto?guid=4959676265405607641" rel="nofollow,noindex">mock测试</a></li>     <li><a href="/misc/goto?guid=4959676265488047882" rel="nofollow,noindex">使用PowerMock来Mock静态函数</a></li>     <li><a href="/misc/goto?guid=4959676265570880607" rel="nofollow,noindex">PowerMock介绍</a></li>     <li><a href="/misc/goto?guid=4959676265657463148" rel="nofollow,noindex">Sharing code between unit tests and instrumentation tests on Android</a></li>     <li><a href="/misc/goto?guid=4959672183663539269" rel="nofollow,noindex">Unit tests with Mockito - Tutorial</a></li>     <li><a href="/misc/goto?guid=4959676265747243172" rel="nofollow,noindex">Android单元测试之Mockito浅析</a></li>     <li><a href="/misc/goto?guid=4959676265836240486" rel="nofollow,noindex">Mockito 简明教程</a></li>     <li><a href="/misc/goto?guid=4959676265920251969" rel="nofollow,noindex">mockito简单教程</a></li>    </ol>    <p> </p>    <p>来自：http://snowdream.github.io/blog/2016/08/03/android-mock-test/</p>    <p> </p>