hasStrings on Android (flutter#20393)

hasStrings message for checking for pasteable clipboard contents without actually reading them, for iOS14 clipboard alerts.

Author: justinmc

shell/platform/android/BUILD.gn

@@ -435,6 +435,7 @@ action("robolectric_tests") {
     "test/io/flutter/embedding/engine/loader/ApplicationInfoLoaderTest.java",
     "test/io/flutter/embedding/engine/plugins/shim/ShimPluginRegistryTest.java",
     "test/io/flutter/embedding/engine/renderer/FlutterRendererTest.java",
+    "test/io/flutter/embedding/engine/systemchannels/PlatformChannelTest.java",
     "test/io/flutter/embedding/engine/systemchannels/RestorationChannelTest.java",
     "test/io/flutter/external/FlutterLaunchTests.java",
     "test/io/flutter/plugin/common/StandardMessageCodecTest.java",

shell/platform/android/io/flutter/embedding/engine/systemchannels/PlatformChannel.java

@@ -30,7 +30,7 @@ public class PlatformChannel {
   @Nullable private PlatformMessageHandler platformMessageHandler;
 
   @NonNull @VisibleForTesting
-  protected final MethodChannel.MethodCallHandler parsingMethodCallHandler =
+  final MethodChannel.MethodCallHandler parsingMethodCallHandler =
       new MethodChannel.MethodCallHandler() {
         @Override
         public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result result) {
@@ -155,6 +155,14 @@ public void onMethodCall(@NonNull MethodCall call, @NonNull MethodChannel.Result
                   result.success(null);
                   break;
                 }
+              case "Clipboard.hasStrings":
+                {
+                  boolean hasStrings = platformMessageHandler.clipboardHasStrings();
+                  JSONObject response = new JSONObject();
+                  response.put("value", hasStrings);
+                  result.success(response);
+                  break;
+                }
               default:
                 result.notImplemented();
                 break;
@@ -426,6 +434,12 @@ public interface PlatformMessageHandler {
      * {@code text}.
      */
     void setClipboardData(@NonNull String text);
+
+    /**
+     * The Flutter application would like to know if the clipboard currently contains a string that
+     * can be pasted.
+     */
+    boolean clipboardHasStrings();
   }
 
   /** Types of sounds the Android OS can play on behalf of an application. */

shell/platform/android/io/flutter/plugin/platform/PlatformPlugin.java

@@ -30,7 +30,8 @@ public class PlatformPlugin {
   private PlatformChannel.SystemChromeStyle currentTheme;
   private int mEnabledOverlays;
 
-  private final PlatformChannel.PlatformMessageHandler mPlatformMessageHandler =
+  @VisibleForTesting
+  final PlatformChannel.PlatformMessageHandler mPlatformMessageHandler =
       new PlatformChannel.PlatformMessageHandler() {
         @Override
         public void playSystemSound(@NonNull PlatformChannel.SoundType soundType) {
@@ -85,6 +86,14 @@ public CharSequence getClipboardData(
         public void setClipboardData(@NonNull String text) {
           PlatformPlugin.this.setClipboardData(text);
         }
+
+        @Override
+        public boolean clipboardHasStrings() {
+          CharSequence data =
+              PlatformPlugin.this.getClipboardData(
+                  PlatformChannel.ClipboardContentFormat.PLAIN_TEXT);
+          return data != null && data.length() > 0;
+        }
       };
 
   public PlatformPlugin(Activity activity, PlatformChannel platformChannel) {

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

@@ -17,6 +17,7 @@
 import io.flutter.embedding.engine.RenderingComponentTest;
 import io.flutter.embedding.engine.plugins.shim.ShimPluginRegistryTest;
 import io.flutter.embedding.engine.renderer.FlutterRendererTest;
+import io.flutter.embedding.engine.systemchannels.PlatformChannelTest;
 import io.flutter.embedding.engine.systemchannels.RestorationChannelTest;
 import io.flutter.external.FlutterLaunchTests;
 import io.flutter.plugin.common.StandardMessageCodecTest;
@@ -68,6 +69,7 @@
   TextInputPluginTest.class,
   MouseCursorPluginTest.class,
   AccessibilityBridgeTest.class,
+  PlatformChannelTest.class,
   RestorationChannelTest.class,
 })
 /** Runs all of the unit tests listed in the {@code @SuiteClasses} annotation. */

shell/platform/android/test/io/flutter/embedding/engine/systemchannels/PlatformChannelTest.java

@@ -0,0 +1,45 @@
+package io.flutter.embedding.engine.systemchannels;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+import android.content.res.AssetManager;
+import io.flutter.embedding.engine.FlutterJNI;
+import io.flutter.embedding.engine.dart.DartExecutor;
+import io.flutter.plugin.common.MethodCall;
+import io.flutter.plugin.common.MethodChannel;
+import org.json.JSONException;
+import org.json.JSONObject;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.mockito.Matchers;
+import org.robolectric.RobolectricTestRunner;
+import org.robolectric.annotation.Config;
+
+@Config(manifest = Config.NONE)
+@RunWith(RobolectricTestRunner.class)
+public class PlatformChannelTest {
+  @Test
+  public void platformChannel_hasStringsMessage() {
+    MethodChannel rawChannel = mock(MethodChannel.class);
+    FlutterJNI mockFlutterJNI = mock(FlutterJNI.class);
+    DartExecutor dartExecutor = new DartExecutor(mockFlutterJNI, mock(AssetManager.class));
+    PlatformChannel fakePlatformChannel = new PlatformChannel(dartExecutor);
+    PlatformChannel.PlatformMessageHandler mockMessageHandler =
+        mock(PlatformChannel.PlatformMessageHandler.class);
+    fakePlatformChannel.setPlatformMessageHandler(mockMessageHandler);
+    Boolean returnValue = true;
+    when(mockMessageHandler.clipboardHasStrings()).thenReturn(returnValue);
+    MethodCall methodCall = new MethodCall("Clipboard.hasStrings", null);
+    MethodChannel.Result mockResult = mock(MethodChannel.Result.class);
+    fakePlatformChannel.parsingMethodCallHandler.onMethodCall(methodCall, mockResult);
+
+    JSONObject expected = new JSONObject();
+    try {
+      expected.put("value", returnValue);
+    } catch (JSONException e) {
+    }
+    verify(mockResult).success(Matchers.refEq(expected));
+  }
+}

shell/platform/android/test/io/flutter/plugin/platform/PlatformPluginTest.java

@@ -1,15 +1,20 @@
 package io.flutter.plugin.platform;
 
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.when;
 
 import android.app.Activity;
+import android.content.ClipboardManager;
+import android.content.Context;
 import android.view.View;
 import android.view.Window;
 import io.flutter.embedding.engine.systemchannels.PlatformChannel;
 import org.junit.Test;
 import org.junit.runner.RunWith;
 import org.robolectric.RobolectricTestRunner;
+import org.robolectric.RuntimeEnvironment;
 import org.robolectric.annotation.Config;
 
 @Config(manifest = Config.NONE)
@@ -32,4 +37,25 @@ public void itIgnoresNewHapticEventsOnOldAndroidPlatforms() {
     // SELECTION_CLICK haptic response is only available on "LOLLIPOP" (21) and later.
     platformPlugin.vibrateHapticFeedback(PlatformChannel.HapticFeedbackType.SELECTION_CLICK);
   }
+
+  @Test
+  public void platformPlugin_hasStrings() {
+    ClipboardManager clipboardManager =
+        RuntimeEnvironment.application.getSystemService(ClipboardManager.class);
+
+    View fakeDecorView = mock(View.class);
+    Window fakeWindow = mock(Window.class);
+    when(fakeWindow.getDecorView()).thenReturn(fakeDecorView);
+    Activity fakeActivity = mock(Activity.class);
+    when(fakeActivity.getWindow()).thenReturn(fakeWindow);
+    when(fakeActivity.getSystemService(Context.CLIPBOARD_SERVICE)).thenReturn(clipboardManager);
+    PlatformChannel fakePlatformChannel = mock(PlatformChannel.class);
+    PlatformPlugin platformPlugin = new PlatformPlugin(fakeActivity, fakePlatformChannel);
+
+    clipboardManager.setText("iamastring");
+    assertTrue(platformPlugin.mPlatformMessageHandler.clipboardHasStrings());
+
+    clipboardManager.setText("");
+    assertFalse(platformPlugin.mPlatformMessageHandler.clipboardHasStrings());
+  }
 }