Chame waitForMonitorWithTimeout () de um @UiThreadTest

Para ilustrar meu problema mais recente ao escrever testes JUnit para meu aplicativo Android, escrevi um exemplo simples com duas atividades, StartActivityForResult e ChildActivity . O primeiro contém um TextView (para fins de exibição) e um Button enquanto o último contém apenas um Button . O onClickListener para o botão em StartActivityForResult simplesmente inicia uma instância de ChildActivity .

 private View.OnClickListener onStart = new View.OnClickListener() { @Override public void onClick(View view) { Log.d(TAG, "Start button clicked"); Intent intent = new Intent(StartActivityForResult.this, ChildActivity.class); StartActivityForResult.this.startActivityForResult(intent, R.id.child_request); } }; 

Agora quero testar esse método usando JUnit. Então eu escrevi o seguinte teste:

 package codeguru.startactivityforresult; import android.app.Activity; import android.app.Instrumentation; import android.content.Intent; import android.test.ActivityInstrumentationTestCase2; import android.test.UiThreadTest; import android.util.Log; import android.widget.Button; import android.widget.TextView; import junit.framework.Assert; public class StartActivityForResultTest extends ActivityInstrumentationTestCase2 { public StartActivityForResultTest() { super(StartActivityForResult.class); } @Override public void setUp() throws Exception { super.setUp(); Log.d(TAG, "setUp()"); this.setActivityInitialTouchMode(false); this.activity = this.getActivity(); this.resultText = (TextView) this.activity.findViewById(R.id.result_text); this.startButton = (Button) this.activity.findViewById(R.id.start_button); Intent data = new Intent(); data.putExtra(this.activity.getString(R.string.result), RESULT); Instrumentation.ActivityResult result = new Instrumentation.ActivityResult(Activity.RESULT_OK, data); this.childMonitor = new Instrumentation.ActivityMonitor(ChildActivity.class.getName(), result, true); this.getInstrumentation().addMonitor(this.childMonitor); } @Override public void tearDown() throws Exception { this.activity.finish(); super.tearDown(); } @UiThreadTest public void testStartButtonOnClick() { Assert.assertTrue(this.startButton.performClick()); Activity childActivity = this.getInstrumentation().waitForMonitorWithTimeout(this.childMonitor, TIME_OUT); Assert.assertNotNull(childActivity); // <------ Line 51 Button resultButton = (Button) childActivity.findViewById(R.id.result_button); Assert.assertTrue(resultButton.performClick()); Assert.assertEquals(Integer.toString(RESULT), this.resultText.getText().toString()); } private Activity activity = null; private TextView resultText = null; private Button startButton = null; private Instrumentation.ActivityMonitor childMonitor = null; private static final int TIME_OUT = 5 * 1000; // 5 seconds private static final int RESULT = 69; private static final String TAG = StartActivityForResultTest.class.getName(); } 

A execução deste teste fornece a seguinte saída:

 codeguru@trolloc:~/src/java/stackoverflow/sscce/StartActivityForResult/test$ adb logcat -c codeguru@trolloc:~/src/java/stackoverflow/sscce/StartActivityForResult/test$ adb shell am instrument -w -e class codeguru.startactivityforresult.StartActivityForResultTest codeguru.startactivityforresult.tests/android.test.InstrumentationTestRunner codeguru.startactivityforresult.StartActivityForResultTest: Failure in testStartButtonOnClick: junit.framework.AssertionFailedError at codeguru.startactivityforresult.StartActivityForResultTest.testStartButtonOnClick(StartActivityForResultTest.java:51) at java.lang.reflect.Method.invokeNative(Native Method) at android.test.InstrumentationTestCase.runMethod(InstrumentationTestCase.java:214) at android.test.InstrumentationTestCase.access$000(InstrumentationTestCase.java:36) at android.test.InstrumentationTestCase$2.run(InstrumentationTestCase.java:189) at android.app.Instrumentation$SyncRunnable.run(Instrumentation.java:1602) at android.os.Handler.handleCallback(Handler.java:615) at android.os.Handler.dispatchMessage(Handler.java:92) at android.os.Looper.loop(Looper.java:137) at android.app.ActivityThread.main(ActivityThread.java:4745) at java.lang.reflect.Method.invokeNative(Native Method) at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:786) at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:553) at dalvik.system.NativeStart.main(Native Method) Test results for InstrumentationTestRunner=.F Time: 3.248 FAILURES!!! Tests run: 1, Failures: 1, Errors: 0 codeguru@trolloc:~/src/java/stackoverflow/sscce/StartActivityForResult/test$ adb logcat -d codeguru.startactivityforresult.StartActivityForResultTest:D codeguru.startactivityforresult.StartActivityForResult:D codeguru.startactivityforresult.ChildActivity:D *:S D/codeguru.startactivityforresult.StartActivityForResultTest( 954): setUp() D/codeguru.startactivityforresult.StartActivityForResult( 954): onCreate() D/codeguru.startactivityforresult.StartActivityForResult( 954): Start button clicked layne@trolloc:~/src/java/stackoverflow/sscce/StartActivityForResult/test$ 

Tanto quanto eu posso dizer, chamando startButton.performClick() não inicia uma instância de ChildActivity . O que da?

Como ilustrado em uma resposta a uma das minhas perguntas relacionadas , o problema é que estou chamando waitForMonitorWithTimeout() no thread da interface do usuário. Depois de perceber isso, certamente faz todo o sentido porque waitForMonitorWithTimeout() aguarda o thread da interface do usuário para concluir alguma ação (ou seja, exibindo uma interface do usuário da Activity). No entanto, chamando-o no thread da interface do usuário, estou atrasando essa ação.