Convert LooperExecutorTest in AppRTC Demo into JUnit test

webrtc/examples/androidjunit/src/org/appspot/apprtc/util/LooperExecutorTest.java

Index: webrtc/examples/androidjunit/src/org/appspot/apprtc/util/LooperExecutorTest.java
diff --git a/webrtc/examples/androidjunit/src/org/appspot/apprtc/util/LooperExecutorTest.java b/webrtc/examples/androidjunit/src/org/appspot/apprtc/util/LooperExecutorTest.java
new file mode 100644
index 0000000000000000000000000000000000000000..02d5f9363cb592415a044f3c339d75c1f9863cb2
--- /dev/null
+++ b/webrtc/examples/androidjunit/src/org/appspot/apprtc/util/LooperExecutorTest.java
@@ -0,0 +1,106 @@
+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+package org.appspot.apprtc.util;
+
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Mock;
+import org.mockito.MockitoAnnotations;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+import org.robolectric.shadows.ShadowLooper;
+
+import static org.mockito.Mockito.times;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.verifyNoMoreInteractions;
+import static org.robolectric.Robolectric.shadowOf;
+
+@RunWith(RobolectricTestRunner.class)
+@Config(manifest = Config.NONE)
+public class LooperExecutorTest {
+  private final static int RUN_TIMES = 10;
+
+  @Mock private Runnable mockRunnable;
+  private LooperExecutor executor;
+
+  @Before
+  public void setUp() {
+    MockitoAnnotations.initMocks(this);
+    executor = new LooperExecutor();
+  }
+
+  @After
+  public void tearDown() {
+    executor.requestStop();
+    ShadowLooper shadowLooper = getShadowLooper();
+    shadowLooper.idle();
+  }
+
+  @Test
+  public void testExecute() {
+    executor.requestStart();
+    ShadowLooper shadowLooper = getShadowLooper();
+
+    for (int i = 0; i < RUN_TIMES; i++) {
+      executor.execute(mockRunnable);
+    }
+
+    verifyNoMoreInteractions(mockRunnable);
+    shadowLooper.idle();

[magjed_webrtc, 2016/05/19 12:17:13]

What happens when shadowLooper.idle() is called? Are the pending Runnables
executed at that point? It looks like calling idle() is the only operation that
happens on shadowLooper. Can you make that a function instead and comment about
the behaviour.

[sakal, 2016/05/19 13:04:38]

That is correct. Done.

+    verify(mockRunnable, times(RUN_TIMES)).run();
+  }
+
+  @Test
+  public void testExecuteBeforeStart() {

[magjed_webrtc, 2016/05/19 12:17:13]

Comment that calls to execute() before requestStart() are ignored.

[sakal, 2016/05/19 13:04:38]

Done.

+    executor.execute(mockRunnable);
+    verifyNoMoreInteractions(mockRunnable);
+
+    executor.requestStart();
+    ShadowLooper shadowLooper = getShadowLooper();
+    shadowLooper.idle();
+
+    verifyNoMoreInteractions(mockRunnable);

[magjed_webrtc, 2016/05/19 12:17:13]

Isn't enough with one verifyNoMoreInteractions(mockRunnable)?

[sakal, 2016/05/19 13:04:38]

Done.

+  }
+
+  @Test
+  public void testExecuteAfterStop() {

[magjed_webrtc, 2016/05/19 12:17:13]

Comment that calls to execute() after requestStop() are ignored.

[sakal, 2016/05/19 13:04:38]

Done.

+    executor.requestStart();
+    ShadowLooper shadowLooper = getShadowLooper();
+    executor.requestStop();
+
+    executor.execute(mockRunnable);
+    verifyNoMoreInteractions(mockRunnable);
+    shadowLooper.idle();
+
+    verifyNoMoreInteractions(mockRunnable);
+  }
+
+  @Test
+  public void testMultipleStarts() {

[magjed_webrtc, 2016/05/19 12:17:13]

Comment that extra requestStart() calls are ok and just ignored.

[sakal, 2016/05/19 13:04:38]

Done.

+    executor.requestStart();
+    testExecute();
+  }
+
+  @Test
+  public void testMultipleStops() {
+    executor.requestStart();
+    executor.requestStop();
+    executor.requestStop();
+    ShadowLooper shadowLooper = getShadowLooper();
+    shadowLooper.idle();
+  }
+
+  private ShadowLooper getShadowLooper() {
+    return shadowOf(executor.getHandler().getLooper());
+  }
+}