Android中JUnit4 UiAutomator测试进程启动后迅速终止且无异常

在Android环境下使用JUnit4编写的UiAutomator测试用例，执行时仅打印少量System.out输出后就迅速完成，调试模式下表现一致。Logcat显示进程已结束，但未捕获到任何异常，代码编译无错误；即使附加调试器测试，仍执行失败。

测试代码如下：

/**
 * Basic sample for unbundled UiAutomator.
 */
@RunWith(AndroidJUnit4.class)
@SdkSuppress(minSdkVersion = 18)
public class UITestPOC {

    private static final String BASIC_SAMPLE_PACKAGE
            = "com.test.basic";

    private static final int LAUNCH_TIMEOUT = 50000;

    private static final String STRING_TO_BE_TYPED = "UiAutomator";

    private UiDevice mDevice;

    @Before
    public void startMainActivityFromHomeScreen() {
        // Initialize UiDevice instance
        System.out.println("before device init");
        Instrumentation instr = InstrumentationRegistry.getInstrumentation();
        mDevice = UiDevice.getInstance(instr);

        // Start from the home screen
        mDevice.pressHome();
        System.out.println("after press home");

        // Wait for launcher
        final String launcherPackage = getLauncherPackageName();
        assertThat(launcherPackage, notNullValue());
        mDevice.wait(Until.hasObject(By.pkg(launcherPackage).depth(0)), LAUNCH_TIMEOUT);

        // Launch the blueprint app
        Context context = getApplicationContext();
        final Intent intent = context.getPackageManager()
                .getLaunchIntentForPackage(BASIC_SAMPLE_PACKAGE);
        intent.addFlags(Intent.FLAG_ACTIVITY_CLEAR_TASK);    // Clear out any previous instances
        context.startActivity(intent);

        // Wait for the app to appear
        mDevice.wait(Until.hasObject(By.pkg(BASIC_SAMPLE_PACKAGE).depth(0)), LAUNCH_TIMEOUT);
    }


    private String getLauncherPackageName() {
        // Create launcher Intent
        final Intent intent = new Intent(Intent.ACTION_MAIN);
        intent.addCategory(Intent.CATEGORY_HOME);

        // Use PackageManager to get the launcher package name
        PackageManager pm = getApplicationContext().getPackageManager();
        ResolveInfo resolveInfo = pm.resolveActivity(intent, PackageManager.MATCH_DEFAULT_ONLY);
        return resolveInfo.activityInfo.packageName;
    }

    @Test
    public void testChangeText_sameActivity() {
        // Type text and then press the button.
        mDevice.findObject(By.res(BASIC_SAMPLE_PACKAGE, "editTextUserInput"))
                .setText(STRING_TO_BE_TYPED);
        mDevice.findObject(By.res(BASIC_SAMPLE_PACKAGE, "changeTextBt"))
                .click();

        // Verify the test is displayed in the Ui
        UiObject2 changedText = mDevice
                .wait(Until.findObject(By.res(BASIC_SAMPLE_PACKAGE, "textToBeChanged")),
                        500 /* wait 500ms */);
        assertThat(changedText.getText(), is(equalTo(STRING_TO_BE_TYPED)));
    }

}

• 检查测试配置与依赖
  确认测试模块build.gradle中UiAutomator和JUnit依赖配置正确：

  androidTestImplementation 'androidx.test.uiautomator:uiautomator:2.2.0'
  androidTestImplementation 'androidx.test.ext:junit:1.1.5'
  

  同时确保AndroidManifest.xml声明了必要权限：

  <uses-permission android:name="android.permission.GET_TASKS"/>
  

• 显式检查@Before方法中的隐性失败点
  代码中assertThat(launcherPackage, notNullValue())断言失败时，会直接终止测试但无明确日志。替换为显式空值检查并抛出异常：

  if (launcherPackage == null) {
      throw new RuntimeException("无法获取Launcher包名");
  }
  

  启动目标应用前，先确认Intent不为空：

  if (intent == null) {
      throw new RuntimeException("未找到目标应用启动Intent，检查包名：" + BASIC_SAMPLE_PACKAGE);
  }
  

• 优化等待逻辑与日志输出
  把测试方法中控件等待时间从500ms延长至3000ms，避免因控件加载慢导致查找失败；同时用Log.d替代System.out，确保日志能正常输出：

  Log.d("UITestPOC", "before device init");
  // ...
  UiObject2 changedText = mDevice
          .wait(Until.findObject(By.res(BASIC_SAMPLE_PACKAGE, "textToBeChanged")),
                  3000);
  

• 校验目标应用控件ID
  确认被测应用中editTextUserInput、changeTextBt、textToBeChanged的控件ID与测试代码完全一致，避免因ID拼写错误导致控件查找失败。

内容的提问来源于stack exchange，提问作者Hemanth