diff --git a/packages/flutter/lib/src/services/shell.dart b/packages/flutter/lib/src/services/shell.dart
index 88b21403379..3f3f4112dff 100644
--- a/packages/flutter/lib/src/services/shell.dart
+++ b/packages/flutter/lib/src/services/shell.dart
@@ -18,15 +18,33 @@ ApplicationConnection _initConnection() {
   return new ApplicationConnection(null, serviceProvider);
 }
 
+// A replacement for requestService.  Implementations should return true
+// if they handled the request, or false if the request should fall through
+// to the default requestService.
+typedef bool OverrideRequestService(String url, Object proxy);
+
+// Set this to intercept calls to requestService and supply an alternative
+// implementation of a service (for example, a mock for testing).
+OverrideRequestService overrideRequestService;
+
 class _ShellImpl {
   _ShellImpl._();
 
   final ApplicationConnection _connection = _initConnection();
 
-  void requestService(String url, Object proxy) {
+  void _requestService(String url, Object proxy) {
     if (embedder.shell == null) _connection.requestService(proxy);
     else embedder.connectToService(url, proxy);
   }
+
+  void requestService(String url, Object proxy) {
+    if (overrideRequestService != null) {
+      if (overrideRequestService(url, proxy))
+        return;
+    }
+
+    _requestService(url, proxy);
+  }
 }
 
 final _ShellImpl shell = new _ShellImpl._();
diff --git a/packages/flutter/lib/src/widgets/editable_text.dart b/packages/flutter/lib/src/widgets/editable_text.dart
index 82794c92678..3280da4c235 100644
--- a/packages/flutter/lib/src/widgets/editable_text.dart
+++ b/packages/flutter/lib/src/widgets/editable_text.dart
@@ -205,7 +205,7 @@ class EditableText extends StatefulComponent {
 
     if (!value.composing.isValid) {
       // TODO(eseidel): This is the wrong height if empty!
-      return new Text(value.text, style: style);
+      return new Row([new Text(value.text, style: style)]);
     }
 
     TextStyle composingStyle = style.merge(const TextStyle(decoration: underline));
diff --git a/packages/unit/test/services/mock_services.dart b/packages/unit/test/services/mock_services.dart
new file mode 100644
index 00000000000..264d597f55f
--- /dev/null
+++ b/packages/unit/test/services/mock_services.dart
@@ -0,0 +1,31 @@
+import 'package:sky/src/services/shell.dart' as shell;
+
+// Tests can use ServiceMocker to register replacement implementations
+// of Mojo services.
+class _ServiceMocker {
+  _ServiceMocker() {
+    shell.overrideRequestService = _requestService;
+  }
+
+  // Map of interface names to mock implementations.
+  Map<String, Object> _interfaceMock = new Map<String, Object>();
+
+  bool _requestService(String url, Object proxy) {
+    Object mock = _interfaceMock[proxy.impl.name];
+    if (mock != null) {
+      // Replace the proxy's implementation of the service interface with the
+      // mock.
+      proxy.ptr = mock;
+      return true;
+    } else {
+      return false;
+    }
+  }
+
+  // Provide a mock implementation for a Mojo interface.
+  void registerMockService(String interfaceName, Object mock) {
+    _interfaceMock[interfaceName] = mock;
+  }
+}
+
+final _ServiceMocker serviceMocker = new _ServiceMocker();
diff --git a/packages/unit/test/widget/input_test.dart b/packages/unit/test/widget/input_test.dart
new file mode 100644
index 00000000000..7628ccd1aa5
--- /dev/null
+++ b/packages/unit/test/widget/input_test.dart
@@ -0,0 +1,59 @@
+import 'package:mojo_services/keyboard/keyboard.mojom.dart';
+import 'package:sky/services.dart';
+import 'package:sky/widgets.dart';
+import 'package:test/test.dart';
+
+import 'widget_tester.dart';
+import '../services/mock_services.dart';
+
+class MockKeyboard implements KeyboardService {
+  KeyboardClient client;
+
+  void show(Object client, int type) {
+    this.client = client.impl;
+  }
+
+  void showByRequest() {}
+
+  void hide() {}
+}
+
+void main() {
+  test('Editable text has consistent width', () {
+    WidgetTester tester = new WidgetTester();
+
+    MockKeyboard mockKeyboard = new MockKeyboard();
+    serviceMocker.registerMockService(KeyboardServiceName, mockKeyboard);
+
+    GlobalKey inputKey = new GlobalKey();
+    String inputValue;
+
+    Widget builder() {
+      return new Center(
+        child: new Input(
+          key: inputKey,
+          placeholder: 'Placeholder',
+          onChanged: (value) { inputValue = value; }
+        )
+      );
+    }
+
+    tester.pumpFrame(builder);
+
+    Input input = tester.findWidget((Widget widget) => widget.key == inputKey);
+    Size emptyInputSize = input.renderObject.size;
+
+    // Simulate entry of text through the keyboard.
+    expect(mockKeyboard.client, isNotNull);
+    const String testValue = 'Test';
+    mockKeyboard.client.setComposingText(testValue, testValue.length);
+
+    // Check that the onChanged event handler fired.
+    expect(inputValue, equals(testValue));
+
+    tester.pumpFrame(builder);
+
+    // Check that the Input with text has the same size as the empty Input.
+    expect(input.renderObject.size, equals(emptyInputSize));
+  });
+}