Add tests

Author: WasserEsser

shell/platform/android/test/io/flutter/FlutterTestSuite.java

@@ -24,6 +24,7 @@
 import io.flutter.embedding.engine.loader.ApplicationInfoLoaderTest;
 import io.flutter.embedding.engine.loader.FlutterLoaderTest;
 import io.flutter.embedding.engine.mutatorsstack.FlutterMutatorViewTest;
+import io.flutter.embedding.engine.mutatorsstack.FlutterMutatorsStackTest;
 import io.flutter.embedding.engine.plugins.shim.ShimPluginRegistryTest;
 import io.flutter.embedding.engine.renderer.FlutterRendererTest;
 import io.flutter.embedding.engine.systemchannels.DeferredComponentChannelTest;
@@ -73,6 +74,7 @@
   FlutterJNITest.class,
   FlutterLaunchTests.class,
   FlutterLoaderTest.class,
+  FlutterMutatorsStackTest.class,
   FlutterMutatorViewTest.class,
   FlutterShellArgsTest.class,
   FlutterRendererTest.class,

shell/platform/android/test/io/flutter/embedding/engine/mutatorsstack/FlutterMutatorViewTest.java

@@ -1,10 +1,13 @@
 package io.flutter.embedding.engine.mutatorsstack;
 
+import static android.view.View.LAYER_TYPE_HARDWARE;
 import static android.view.View.OnFocusChangeListener;
 import static junit.framework.TestCase.*;
 import static org.mockito.Mockito.*;
 
+import android.graphics.Canvas;
 import android.graphics.Matrix;
+import android.graphics.Paint;
 import android.view.MotionEvent;
 import android.view.View;
 import android.view.ViewGroup;
@@ -250,4 +253,20 @@ public ViewTreeObserver getViewTreeObserver() {
     view.unsetOnDescendantFocusChangeListener();
     verify(viewTreeObserver, times(1)).removeOnGlobalFocusChangeListener(activeFocusListener);
   }
+
+  @Test
+  public void draw_opacityApplied() {
+    final FlutterMutatorView view = new FlutterMutatorView(RuntimeEnvironment.systemContext);
+    final FlutterMutatorView spy = spy(view);
+
+    final FlutterMutatorsStack mutatorsStack = new FlutterMutatorsStack();
+    mutatorsStack.pushOpacity(.3f);
+
+    spy.readyToDisplay(mutatorsStack, /*left=*/ 1, /*top=*/ 2, /*width=*/ 0, /*height=*/ 0);
+    spy.draw(new Canvas());
+    verify(spy)
+        .setLayerType(
+            intThat((Integer layerType) -> layerType == LAYER_TYPE_HARDWARE),
+            argThat((Paint paint) -> paint.getAlpha() == (int) (.3f * 255)));
+  }
 }

shell/platform/android/test/io/flutter/embedding/engine/mutatorsstack/FlutterMutatorsStackTest.java

@@ -0,0 +1,42 @@
+package io.flutter.embedding.engine.mutatorsstack;
+
+import static org.junit.Assert.assertEquals;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+@Config(manifest = Config.NONE)
+@RunWith(RobolectricTestRunner.class)
+public class FlutterMutatorsStackTest {
+
+  @Test
+  public void pushOpacity() {
+    final FlutterMutatorsStack mutatorsStack = new FlutterMutatorsStack();
+    mutatorsStack.pushOpacity(.5f);
+
+    assertEquals(mutatorsStack.getMutators().size(), 1);
+    assertEquals(
+        mutatorsStack.getMutators().get(0).getType(),
+        FlutterMutatorsStack.FlutterMutatorType.OPACITY);
+    assertEquals(mutatorsStack.getMutators().get(0).getOpacity(), .5f, 0f);
+  }
+
+  @Test
+  public void defaultOpacity() {
+    final FlutterMutatorsStack mutatorsStack = new FlutterMutatorsStack();
+
+    assertEquals(1f, mutatorsStack.getFinalOpacity(), 0f);
+  }
+
+  @Test
+  public void layeredOpacity() {
+    final FlutterMutatorsStack mutatorsStack = new FlutterMutatorsStack();
+    mutatorsStack.pushOpacity(.5f);
+    mutatorsStack.pushOpacity(.6f);
+    mutatorsStack.pushOpacity(1f);
+
+    assertEquals(.3f, mutatorsStack.getFinalOpacity(), 1 / 255);
+  }
+}