Added tests.

Author: matthew-carroll

shell/platform/android/BUILD.gn

@@ -422,6 +422,7 @@ action("robolectric_tests") {
     "test/io/flutter/embedding/engine/FlutterEngineCacheTest.java",
     "test/io/flutter/embedding/engine/FlutterEngineTest.java",
     "test/io/flutter/embedding/engine/FlutterJNITest.java",
+    "test/io/flutter/embedding/engine/PluginComponentTest.java",
     "test/io/flutter/embedding/engine/RenderingComponentTest.java",
     "test/io/flutter/embedding/engine/dart/DartExecutorTest.java",
     "test/io/flutter/embedding/engine/plugins/shim/ShimPluginRegistryTest.java",

shell/platform/android/io/flutter/embedding/engine/FlutterEngine.java

@@ -207,7 +207,8 @@ public FlutterEngine(
 
     this.pluginRegistry = new FlutterEnginePluginRegistry(
       context.getApplicationContext(),
-      this
+      this,
+      flutterLoader
     );
 
     if (automaticallyRegisterPlugins) {

shell/platform/android/io/flutter/embedding/engine/FlutterEnginePluginRegistry.java

@@ -91,7 +91,8 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
 
   FlutterEnginePluginRegistry(
       @NonNull Context appContext,
-      @NonNull FlutterEngine flutterEngine
+      @NonNull FlutterEngine flutterEngine,
+      @NonNull FlutterLoader flutterLoader
   ) {
     this.flutterEngine = flutterEngine;
     pluginBinding = new FlutterPlugin.FlutterPluginBinding(
@@ -100,7 +101,7 @@ class FlutterEnginePluginRegistry implements PluginRegistry,
         flutterEngine.getDartExecutor(),
         flutterEngine.getRenderer(),
         flutterEngine.getPlatformViewsController().getRegistry(),
-        new DefaultFlutterAssets(FlutterLoader.getInstance())
+        new DefaultFlutterAssets(flutterLoader)
     );
   }
 

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

@@ -23,6 +23,7 @@
 import io.flutter.plugin.platform.SingleViewPresentationTest;
 import io.flutter.util.PreconditionsTest;
 import test.io.flutter.embedding.engine.FlutterEngineTest;
+import test.io.flutter.embedding.engine.PluginComponentTest;
 import test.io.flutter.embedding.engine.dart.DartExecutorTest;
 
 @RunWith(Suite.class)
@@ -38,6 +39,7 @@
     FlutterRendererTest.class,
     FlutterViewTest.class,
     PlatformChannelTest.class,
+    PluginComponentTest.class,
     PreconditionsTest.class,
     RenderingComponentTest.class,
     StandardMessageCodecTest.class,

shell/platform/android/test/io/flutter/embedding/engine/PluginComponentTest.java

@@ -0,0 +1,123 @@
+package test.io.flutter.embedding.engine;
+
+import android.support.annotation.NonNull;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.invocation.InvocationOnMock;
+import org.mockito.stubbing.Answer;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
+import org.robolectric.annotation.Config;
+
+import io.flutter.embedding.engine.FlutterEngine;
+import io.flutter.embedding.engine.FlutterJNI;
+import io.flutter.embedding.engine.loader.FlutterLoader;
+import io.flutter.embedding.engine.plugins.FlutterPlugin;
+
+import static junit.framework.TestCase.assertEquals;
+import static org.mockito.Matchers.any;
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.when;
+
+@Config(manifest=Config.NONE)
+@RunWith(RobolectricTestRunner.class)
+public class PluginComponentTest {
+  @Test
+  public void pluginsCanAccessFlutterAssetPaths() {
+    // Setup test.
+    FlutterJNI flutterJNI = mock(FlutterJNI.class);
+    when(flutterJNI.isAttached()).thenReturn(true);
+
+    // FlutterLoader is the object to which the PluginRegistry defers for obtaining
+    // the path to a Flutter asset. Ideally in this component test we would use a
+    // real FlutterLoader and directly verify the relationship between FlutterAssets
+    // and FlutterLoader. However, a real FlutterLoader cannot be used in a JVM test
+    // because it would attempt to load native libraries. Therefore, we create a fake
+    // FlutterLoader, but then we defer the corresponding asset lookup methods to the
+    // real FlutterLoader singleton. This test ends up verifying that when FlutterAssets
+    // is queried for an asset path, it returns the real expected path based on real
+    // FlutterLoader behavior.
+    FlutterLoader flutterLoader = mock(FlutterLoader.class);
+    when(flutterLoader.getLookupKeyForAsset(any(String.class))).thenAnswer(new Answer<String>() {
+      @Override
+      public String answer(InvocationOnMock invocation) throws Throwable {
+        // Defer to a real FlutterLoader to return the asset path.
+        String fileNameOrSubpath = (String) invocation.getArguments()[0];
+        return FlutterLoader.getInstance().getLookupKeyForAsset(fileNameOrSubpath);
+      }
+    });
+    when(flutterLoader.getLookupKeyForAsset(any(String.class), any(String.class))).thenAnswer(new Answer<String>() {
+      @Override
+      public String answer(InvocationOnMock invocation) throws Throwable {
+        // Defer to a real FlutterLoader to return the asset path.
+        String fileNameOrSubpath = (String) invocation.getArguments()[0];
+        String packageName = (String) invocation.getArguments()[1];
+        return FlutterLoader.getInstance().getLookupKeyForAsset(fileNameOrSubpath, packageName);
+      }
+    });
+
+    // Execute behavior under test.
+    FlutterEngine flutterEngine = new FlutterEngine(
+        RuntimeEnvironment.application,
+        flutterLoader,
+        flutterJNI
+    );
+
+    // As soon as our plugin is registered it will look up asset paths and store them
+    // for our verification.
+    PluginThatAccessesAssets plugin = new PluginThatAccessesAssets();
+    flutterEngine.getPlugins().add(plugin);
+
+    // Verify results.
+    assertEquals("flutter_assets/fake_asset.jpg", plugin.getAssetPathBasedOnName());
+    assertEquals("flutter_assets/packages/fakepackage/fake_asset.jpg", plugin.getAssetPathBasedOnNameAndPackage());
+    assertEquals("flutter_assets/some/path/fake_asset.jpg", plugin.getAssetPathBasedOnSubpath());
+    assertEquals("flutter_assets/packages/fakepackage/some/path/fake_asset.jpg", plugin.getAssetPathBasedOnSubpathAndPackage());
+  }
+
+  private static class PluginThatAccessesAssets implements FlutterPlugin {
+    private String assetPathBasedOnName;
+    private String assetPathBasedOnNameAndPackage;
+    private String assetPathBasedOnSubpath;
+    private String assetPathBasedOnSubpathAndPackage;
+
+    public String getAssetPathBasedOnName() {
+      return assetPathBasedOnName;
+    }
+
+    public String getAssetPathBasedOnNameAndPackage() {
+      return assetPathBasedOnNameAndPackage;
+    }
+
+    public String getAssetPathBasedOnSubpath() {
+      return assetPathBasedOnSubpath;
+    }
+
+    public String getAssetPathBasedOnSubpathAndPackage() {
+      return assetPathBasedOnSubpathAndPackage;
+    }
+
+    @Override
+    public void onAttachedToEngine(@NonNull FlutterPluginBinding binding) {
+      assetPathBasedOnName = binding
+          .getFlutterAssets()
+          .getAssetFilePathByName("fake_asset.jpg");
+
+      assetPathBasedOnNameAndPackage = binding
+          .getFlutterAssets()
+          .getAssetFilePathByName("fake_asset.jpg", "fakepackage");
+
+      assetPathBasedOnSubpath = binding
+          .getFlutterAssets()
+          .getAssetFilePathByName("some/path/fake_asset.jpg");
+
+      assetPathBasedOnSubpathAndPackage = binding
+          .getFlutterAssets()
+          .getAssetFilePathByName("some/path/fake_asset.jpg", "fakepackage");
+    }
+
+    @Override
+    public void onDetachedFromEngine(@NonNull FlutterPluginBinding binding) {}
+  }
+}