Andriod 单元测试（五）——测试Hilt组件

[soapgu]

• 前言

Hilt是我们选用的必备组件。
我们大多数类都是要注入到安卓对象的。所以为了以后的TDD目标做准备，把Hilt加入到单元测试是必要条件。

• Hilt 测试准备

plugins {
    id 'com.android.application' version '7.3.0' apply false
    id 'com.android.library' version '7.3.0' apply false
     //hilt plugin
    id 'com.google.dagger.hilt.android' version '2.44.2' apply false
}

gradle升级到7.X.X以后project到build.gradle文件使用新写法，需要增加hilt插件

app的build.gradle文件

plugins {
    id 'com.android.application'
    id 'dagger.hilt.android.plugin'
}

dependencies {
    implementation "com.google.dagger:hilt-android:2.44.2"
    annotationProcessor "com.google.dagger:hilt-android-compiler:2.44.2"
    // For local unit tests
    testImplementation 'com.google.dagger:hilt-android-testing:2.44.2'
    testAnnotationProcessor 'com.google.dagger:hilt-compiler:2.44.2'
}

再写个注入对象和Module

public class SampleSingletonClass {
    public String echo(){
        return "hello singleton";
    }
}

@Module
@InstallIn(SingletonComponent.class)
public class SingletonModule {
    @Provides
    public SampleSingletonClass provideObject(){
        return new SampleSingletonClass();
    }
}

注入到MainActivity里面去

@AndroidEntryPoint
public class MainActivity extends AppCompatActivity {
    @Inject
    protected SampleSingletonClass singletonClass;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        this.tv_message = findViewById(R.id.tv_message);
        findViewById(R.id.button_hilt).setOnClickListener( v -> this.tv_message.setText( singletonClass.echo() ) );
    }
}

这样点击测试按钮就直接把TextView的Text改成SampleSingletonClass的输出了
虚拟器设备测试没问题。准备完毕

• Unit Test 的hello world

按照文档来要三步走
To use Hilt in a test:

1. Annotate the test with @HiltAndroidTest,
2. Add the HiltAndroidRule test rule,
3. Use HiltTestApplication for your Android Application class.

好像出师不利啊！

No instrumentation registered! Must run under a registering instrumentation.
java.lang.IllegalStateException: No instrumentation registered! Must run under a registering instrumentation.
	at androidx.test.platform.app.InstrumentationRegistry.getInstrumentation(InstrumentationRegistry.java:45)
	at androidx.test.core.app.ApplicationProvider.getApplicationContext(ApplicationProvider.java:41)
	at dagger.hilt.android.internal.testing.MarkThatRulesRanRule.<init>(MarkThatRulesRanRule.java:43)
	at dagger.hilt.android.testing.HiltAndroidRule.<init>(HiltAndroidRule.java:36)
	at com.demo.myunittest.HiltTest.<init>(HiltTest.java:22)

文档上说得不清不楚的，最后实践下来，主要要加
@RunWith(RobolectricTestRunner.class)

完成单元测试代码

@RunWith(RobolectricTestRunner.class)
@HiltAndroidTest
@Config(application = HiltTestApplication.class)
public class HiltTest {
    @Rule
    public HiltAndroidRule hiltRule = new HiltAndroidRule(this);

    @Inject
    SampleSingletonClass singletonClass;

    @Test
    public void testSingleton() {
        Assert.assertNull(singletonClass);
        hiltRule.inject();
        Assert.assertNotNull( singletonClass );
        Assert.assertEquals( "hello singleton",singletonClass.echo() );
    }
}

头铁下，如果不用测试的HiltTestApplication会怎么样
就用程序的App
@config(application = App.class)

Hilt test, com.demo.myunittest.HiltTest, cannot use a @HiltAndroidApp application but found com.demo.myunittest.App. To fix, configure the test to use HiltTestApplication or a custom Hilt test application generated with @CustomTestApplication.
java.lang.IllegalStateException: Hilt test, com.demo.myunittest.HiltTest, cannot use a @HiltAndroidApp application but found com.demo.myunittest.App. To fix, configure the test to use HiltTestApplication or a custom Hilt test application generated with @CustomTestApplication.

果然报错，报错还蛮人性化。如果要自定义就用@CustomTestApplication

• @TestInstallIn 李代桃僵

不是所有的模块都能测试，有的需要打桩替换，这个@TestInstallIn就是专门用来移形换影的。

A Dagger module annotated with @TestInstallIn allows users to replace an existing @InstallIn module for all tests in a given source set.

一般替换的Moudule和测试代码放一起

components定义模块级别
replaces 定义别替换的模块类

@Module
@TestInstallIn(components = SingletonComponent.class,
replaces = SingletonModule.class)
public class FakeSingletonModule {
    @Provides
    public SampleSingletonClass provideObject(){
        SampleSingletonClass retValue = mock(SampleSingletonClass.class);
        when(retValue.echo()).thenReturn("mocked hilt object echo");
        return retValue;
    }
}

这样测试类看看echo改不改

    @Test
    public void testSingleton() {
        Assert.assertNull(singletonClass);
        hiltRule.inject();
        Assert.assertNotNull( singletonClass );
        Assert.assertEquals( "mocked hilt object echo",singletonClass.echo() );
    }

最后再测试一下Activity注入的桩是不是一样

    @Test
    public void testActivity(){
        try (ActivityController<MainActivity> controller = Robolectric.buildActivity(MainActivity.class)) {
            controller.setup();
            MainActivity activity = controller.get();
            Assert.assertNotNull("inject single in Activity",activity.singletonClass);
            Assert.assertEquals( "mocked hilt object echo",activity.singletonClass.echo() );
        }
    }

测试也蛮顺利，Activity是onCreated()会自动填充的。不需要调用hiltRule.inject();

• 总结

Hilt的特别会我们配了测试组件，使用起来还是蛮方便的。demo体验下暂时没啥问题。下次可以试试真实项目的测试效果了

• 参考链接

• 谷歌开发者—— Hilt 测试指南
• Hilt官网——Testing
• Demo仓库