Android单元测试（二）-实战

一、项目单元测试环境配置

gradle配置：

dependencies {
    // junit4
    testImplementation 'junit:junit:4.12'
    // mokito
    testImplementation "org.mockito:mockito-core:2.8.9"
    testImplementation "org.mockito:mockito-android:2.8.9”
  
    // powermokito
    testImplementation "org.powermock:powermock-module-junit4:1.7.1"
    testImplementation "org.powermock:powermock-api-mockito2:1.7.1"
    testImplementation 'org.powermock:powermock-core:1.7.1'
    testImplementation "org.powermock:powermock-module-junit4-rule:1.7.1"
    testImplementation "org.powermock:powermock-classloading-xstream:1.7.1"
   
    //robolectric
    testImplementation "org.robolectric:robolectric:3.3.1"
}

抽取单测基类：

1）纯java单测基类

@RunWith(RobolectricTestRunner.class)
@Config(manifest = "AndroidManifest.xml", sdk = 21, application = ApplicationStub.class)
public abstract class BaseJavaTest {

    private int androidSdkVersion;

    protected static void log(String msg) {
        System.out.println(msg);
    }

    @Before
    public void init() {
        // 输出日志
        MockitoAnnotations.initMocks(this);
        androidSdkVersion = VERSION.SDK_INT;
    }

    /**
     * hook执行前，测试log
     */
    @Before
    public void startLog() {
        log("======= start =======");
    }

    /**
     * hook执行后，测试log
     */
    @After
    public void endLog() throws NoSuchFieldException, IllegalAccessException {
        log("======= end =======");
        mockVersionSdkIntReturn(androidSdkVersion);
    }

    //基类可以封装一些通用的单测方法

    /**
     * mock sdk 版本
     */
    protected void mockVersionSdkIntReturn(int apiVersion) throws NoSuchFieldException, IllegalAccessException {
        Field sdkInt = VERSION.class.getField("SDK_INT");
        sdkInt.setAccessible(true);
        sdkInt.set(null, apiVersion);
    }
  ...
}

2）PowerMock基类

@RunWith(RobolectricTestRunner.class)
@Config(manifest = "AndroidManifest.xml", sdk = 21, application = ApplicationStub.class)
@PowerMockIgnore({"org.mockito.*", "org.robolectric.*", "android.*", "org.powermock.*"})
public abstract class BasePowerMockTest {

    private int androidSdkVersion;

         //解决powermock和robolectric兼容性
    @Rule
    public PowerMockRule rule = new PowerMockRule();

    protected static void log(String msg) {
        System.out.println(msg);
    }

    @Before
    public void init() {
        // 输出日志
        MockitoAnnotations.initMocks(this);
        androidSdkVersion = VERSION.SDK_INT;
    }

    /**
     * hook执行前，测试log
     */
    @Before
    public void startLog() {
        log("======= start =======");
    }

    /**
     * hook执行后，测试log
     */
    @After
    public void endLog() {
        log("======= end =======");
        try {
            mockVersionSdkIntReturn(androidSdkVersion);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

    protected void mockVersionSdkIntReturn(int apiVersion) throws NoSuchFieldException, IllegalAccessException {
        Field sdkInt = VERSION.class.getField("SDK_INT");
        sdkInt.setAccessible(true);
        sdkInt.set(null, apiVersion);
    }
  ...
}

二、可测代码设计原则

• 充分利用mvp模式；
• 一个函数只做一件事情，不要把几件事揉在一起；
• 通过将查询和行为分离，可以方便对查询做测试；
• 将纯逻辑部分拆分为独立函数，方便测试；
• 函数的依赖尽量通过参数来传递；
• 尽量不要把复杂结构当做参数传递给函数。

好的代码，能极大的避免mock，降低单测书写难度，因此单测某种程度上也能反过来倒逼程序员写出更优秀的代码。

三、Android单测实战场景

mock场景的单测主要包括三大步：构建对象 + 打桩 + 验证行为

3.1 构建对象

• new 常规初始化对象
• mock 构建空实现对象
• spy 构建具体实现对象

注：
类没有依赖且对象好构建，那可以选择new来初始化对象，否则使用mock/spy。前者类对外部依赖较多，只关新少数函数的具体实现；后者类对外依赖较少，关心大部分函数的具体实现。

3.2 打桩

mock对象之后的后续函数操作，doCallRealMethod()、doReturn()、thenReturn()、doNothing()等是比较常用的打桩方法。

1）public/protected/default方法：

mock类执行真实方法

AppManagerModule appManagerModule = Mockito.mock(AppManagerModule.class);
Mockito.doCallRealMethod().when(appManagerModule).isIgnoreApp("22");
boolean res = appManagerModule.isIgnoreApp("22");
Assert.assertFalse(res);

公有方法返回修改值

ActivityManager am = (ActivityManager) context.getSystemService(Context.ACTIVITY_SERVICE);

Context context = Mockito.mock(Context.class);
ActivityManager activityManager = Mockito.mock(ActivityManager.class);
Mockito.doReturn(activityManager).when(context).getSystemService(Mockito.eq(Context.ACTIVITY_SERVICE));

2）private/static/final方法

mock类执行真实方法

AppManagerModule mockAppManagerModule = PowerMockito.mock(AppManagerModule.class);
doCallRealMethod().when(mockAppManagerModule).getDownloadingApkCount();
mockAppManagerModule.getDownloadingApkCount();

静态方法返回修改值

List downloadInfoList = DownloadProxy.getInstance().getDownloadInfoList(DownloadType.APK, true);

DownloadProxy downloadProxy = PowerMockito.mock(DownloadProxy.class);
//类的@PrepareForTest需要添加DownloadProxy.class
PowerMockito.mockStatic(DownloadProxy.class);
//DownloadProxy.getInstance()默认返回mock的downloadProxy实例
PowerMockito.when(DownloadProxy.getInstance()).thenReturn(downloadProxy);
//构建List
ArrayList downloadInfos = new ArrayList<>();
DownloadInfo downloadInfo = new DownloadInfo();
downloadInfos.add(downloadInfo);
//返回设置为构建的list
PowerMockito.when(downloadProxy.getDownloadInfoList(Mockito.any(SimpleDownloadInfo.DownloadType.class),Mockito.anyBoolean())).thenReturn(downloadInfos);

私有方法返回修改值

public class MockPrivateObjectClass {
    public String stepName;
    public MockPrivateObjectClass() {
    }

    private void setStepName() {
        System.out.print("enter setStepName");
        stepName = "has set name";
    }

    public void testStepName() {
        setStepName();
        System.out.print(stepName);
    }
}

  @Test
    public void replacePrivateMethodTest() {
        MockPrivateObjectClass objectClass = new MockPrivateObjectClass();
        PowerMockito.replace(PowerMockito.method(MockPrivateObjectClass.class, "setStepName")).with(new InvocationHandler() {
            @Override
            public Object invoke(Object o, Method method, Object[] objects) throws Throwable {
                Whitebox.setInternalState(o, "stepName", "modify step name");
                return null;
            }
        });
        objectClass.testStepName();
    }

invoke对象私有方法

ObjectWhiteBoxClass objectWhiteBoxClass = new ObjectWhiteBoxClass();
Whitebox.invokeMethod(objectWhiteBoxClass, “addObject", "test1");
Assert.assertEquals(1, objectWhiteBoxClass.getObjectList().size());

3.3 验证行为

验证返回值：

Assert.assertFalse、Assert.assertEquals等

Assert.assertEquals("0", mockAppManagerModule.getPkgScanStatus());
Assert.assertFalse(appManagerModule.isIgnoreApp("22"););

验证方法被调用及其频率：（要求对象是mock对象）

Mockito.verify、PowerMotiko.verifyStatic、Mockito.verifyPrivate等

public/protected/default方法：

NormalClassB b = new MockNormalClassB();
 NormalClassB mockB = Mockito.spy(b);
Mockito.verify(mockB).getName();

Mockito.verify(triggerManager, Mockito.times(1)).showDesktopWindowLocked(
        Mockito.any(Context.class), Mockito.any(DesktopWinTrigger.class),
        Mockito.any(DesktopWinCardInfo.class),
        Mockito.anyLong(), Mockito.anyInt());

static方法：

PowerMockito.verifyStatic(Mockito.times(1));
ToastUtils.show(null, 0x7632343, Toast.LENGTH_SHORT);

private方法：

NormalClassA classA = new NormalClassA(); 
NormalClassA mockClassA = PowerMockito.spy(classA);
PowerMockito.verifyPrivate(mockClassA, times(1)).invoke("privateAdd", Mockito.anyInt(), Mockito.anyInt());

四、常见报错问题处理

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