Add SimpleDialogOption (#7494)

The demo of the SimpleDialog had some useful code that should really be part of
the framework. This patch extracts it into a SimpleDialogOption widget.

Remove debugCheckHasScaffold because it is unused.

Also, add tests for InkWell, SimpleDialog, and other widgets.

examples/flutter_gallery/lib/demo/dialog_demo.dart

@@ -29,22 +29,19 @@ class DialogDemoItem extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
-    return new InkWell(
-      onTap: onPressed,
-      child: new Padding(
-        padding: const EdgeInsets.symmetric(vertical: 8.0, horizontal: 24.0),
-        child: new Row(
-          mainAxisAlignment: MainAxisAlignment.start,
-          crossAxisAlignment: CrossAxisAlignment.center,
-          children: <Widget>[
-            new Icon(icon, size: 36.0, color: color),
-            new Padding(
-              padding: const EdgeInsets.only(left: 16.0),
-              child: new Text(text)
-            )
-          ]
-        )
-      )
+    return new SimpleDialogOption(
+      onPressed: onPressed,
+      child: new Row(
+        mainAxisAlignment: MainAxisAlignment.start,
+        crossAxisAlignment: CrossAxisAlignment.center,
+        children: <Widget>[
+          new Icon(icon, size: 36.0, color: color),
+          new Padding(
+            padding: const EdgeInsets.only(left: 16.0),
+            child: new Text(text),
+          ),
+        ],
+      ),
     );
   }
 }

packages/flutter/lib/src/material/debug.dart

@@ -5,7 +5,6 @@
 import 'package:flutter/widgets.dart';
 
 import 'material.dart';
-import 'scaffold.dart';
 
 /// Asserts that the given context has a [Material] ancestor.
 ///
@@ -42,37 +41,3 @@ bool debugCheckHasMaterial(BuildContext context) {
   });
   return true;
 }
-
-/// Asserts that the given context has a [Scaffold] ancestor.
-///
-/// Used by some material design widgets to make sure that they are
-/// only used in contexts where they can communicate with a Scaffold.
-///
-/// For example, the [AppBar] in some situations requires a Scaffold
-/// to do the right thing with scrolling.
-///
-/// To call this function, use the following pattern, typically in the
-/// relevant Widget's [build] method:
-///
-/// ```dart
-/// assert(debugCheckHasScaffold(context));
-/// ```
-///
-/// Does nothing if asserts are disabled. Always returns true.
-bool debugCheckHasScaffold(BuildContext context) {
-  assert(() {
-    if (Scaffold.of(context) == null) {
-      Element element = context;
-      throw new FlutterError(
-        'No Scaffold widget found.\n'
-        '${context.widget.runtimeType} widgets require a Scaffold widget ancestor.\n'
-        'The specific widget that could not find a Scaffold ancestor was:\n'
-        '  ${context.widget}\n'
-        'The ownership chain for the affected widget is:\n'
-        '  ${element.debugGetCreatorChain(10)}'
-      );
-    }
-    return true;
-  });
-  return true;
-}

packages/flutter/lib/src/material/dialog.dart

@@ -10,6 +10,7 @@ import 'package:meta/meta.dart';
 import 'button.dart';
 import 'button_bar.dart';
 import 'colors.dart';
+import 'ink_well.dart';
 import 'material.dart';
 import 'theme.dart';
 
@@ -176,6 +177,50 @@ class AlertDialog extends StatelessWidget {
   }
 }
 
+/// An option used in a [SimpleDialog].
+///
+/// A simple dialog offers the user a choice between several options. This
+/// widget is commonly used to represent each of the options. If the user
+/// selects this option, the widget will call the [onPressed] callback, which
+/// typically uses [Navigator.pop] to close the dialog.
+///
+/// See also:
+///
+///  * [SimpleDialog], for a dialog in which to use this widget.
+///  * [showDialog], which actually displays the dialog and returns its result.
+///  * [FlatButton], which are commonly used as actions in other kinds of
+///    dialogs, such as [AlertDialog]s.
+///  * <https://material.google.com/components/dialogs.html#dialogs-simple-dialogs>
+class SimpleDialogOption extends StatelessWidget {
+  /// Creates an option for a [SimpleDialog].
+  SimpleDialogOption({
+    Key key,
+    this.onPressed,
+    this.child,
+  }) : super(key: key);
+
+  /// The callback that is called when this option is selected.
+  ///
+  /// If this is set to null, the option cannot be selected.
+  final VoidCallback onPressed;
+
+  /// The widget below this widget in the tree.
+  ///
+  /// Typically a [Text] widget.
+  final Widget child;
+
+  @override
+  Widget build(BuildContext context) {
+    return new InkWell(
+      onTap: onPressed,
+      child: new Padding(
+        padding: const EdgeInsets.symmetric(vertical: 8.0, horizontal: 24.0),
+        child: child
+      ),
+    );
+  }
+}
+
 /// A simple material design dialog.
 ///
 /// A simple dialog offers the user a choice between several options. A simple
@@ -189,6 +234,7 @@ class AlertDialog extends StatelessWidget {
 ///
 /// See also:
 ///
+///  * [SimpleDialogOption], which are options used in this type of dialog.
 ///  * [AlertDialog], for dialogs that have a row of buttons below the body.
 ///  * [Dialog], on which [SimpleDialog] and [AlertDialog] are based.
 ///  * [showDialog], which actually displays the dialog and returns its result.
@@ -220,8 +266,7 @@ class SimpleDialog extends StatelessWidget {
   /// The (optional) content of the dialog is displayed in a [Block] underneath
   /// the title.
   ///
-  /// The children are assumed to have 8.0 pixels of vertical and 24.0 pixels of
-  /// horizontal padding internally.
+  /// Typically a list of [SimpleDialogOption]s.
   final List<Widget> children;
 
   /// Padding around the content.

packages/flutter/lib/src/material/flat_button.dart

@@ -31,8 +31,10 @@ import 'theme.dart';
 ///
 /// See also:
 ///
-///  * [RaisedButton]
-///  * [DropdownButton]
+///  * [RaisedButton], which is a button that hovers above the containing
+///    material.
+///  * [DropdownButton], which offers the user a choice of a number of options.
+///  * [SimpleDialogOption], which is used in [SimpleDialog]s.
 ///  * <https://material.google.com/components/buttons.html>
 class FlatButton extends StatelessWidget {
   /// Creates a flat button.

packages/flutter/lib/src/material/raised_button.dart

@@ -114,13 +114,13 @@ class RaisedButton extends StatelessWidget {
       if (disabledColor != null)
         return disabledColor;
       Brightness brightness = Theme.of(context).brightness;
+      assert(brightness != null);
       switch (brightness) {
         case Brightness.light:
           return Colors.black12;
         case Brightness.dark:
           return Colors.white12;
       }
-      assert(brightness != null);
       return null;
     }
   }

packages/flutter/test/material/arc_test.dart

@@ -6,6 +6,37 @@ import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter/material.dart';
 
 void main() {
+  test('MaterialPointArcTween control test', () {
+    MaterialPointArcTween a = new MaterialPointArcTween(
+      begin: Point.origin,
+      end: const Point(0.0, 10.0)
+    );
+
+    MaterialPointArcTween b = new MaterialPointArcTween(
+      begin: Point.origin,
+      end: const Point(0.0, 10.0)
+    );
+
+    expect(a, hasOneLineDescription);
+    expect(a, equals(b));
+    expect(a.hashCode, equals(b.hashCode));
+  });
+
+  test('MaterialRectArcTween control test', () {
+    MaterialRectArcTween a = new MaterialRectArcTween(
+      begin: new Rect.fromLTWH(0.0, 0.0, 10.0, 10.0),
+      end: new Rect.fromLTWH(0.0, 10.0, 10.0, 10.0)
+    );
+
+    MaterialRectArcTween b = new MaterialRectArcTween(
+      begin: new Rect.fromLTWH(0.0, 0.0, 10.0, 10.0),
+      end: new Rect.fromLTWH(0.0, 10.0, 10.0, 10.0)
+    );
+    expect(a, hasOneLineDescription);
+    expect(a, equals(b));
+    expect(a.hashCode, equals(b.hashCode));
+  });
+
   test('on-axis MaterialPointArcTween', () {
     MaterialPointArcTween tween = new MaterialPointArcTween(
       begin: Point.origin,

packages/flutter/test/material/debug_test.dart

@@ -0,0 +1,16 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('debugCheckHasMaterial control test', (WidgetTester tester) async {
+    await tester.pumpWidget(new FlatButton(
+      onPressed: null,
+      child: new Text('Go'),
+    ));
+    expect(tester.takeException(), isFlutterError);
+  });
+}

packages/flutter/test/material/dialog_test.dart

@@ -55,7 +55,7 @@ void main() {
     await tester.tap(find.text('OK'));
     expect(didPressOk, true);
   });
-  
+
   testWidgets('Dialog background color', (WidgetTester tester) async {
 
     await tester.pumpWidget(
@@ -71,18 +71,18 @@ void main() {
                     showDialog(
                       context: context,
                       child: new AlertDialog(
+                        title: new Text('Title'),
                         content: new Text('Y'),
-                        actions: <Widget>[
-                        ]
-                      )
+                        actions: <Widget>[ ],
+                      ),
                     );
-                  }
-                )
+                  },
+                ),
               );
-            }
-          )
-        )
-      )
+            },
+          ),
+        ),
+      ),
     );
 
     await tester.tap(find.text('X'));
@@ -96,4 +96,49 @@ void main() {
     expect(materialconfig.elevation, 24);
     expect(materialconfig.color, Colors.grey[800]);
   });
+
+  testWidgets('Simple dialog control test', (WidgetTester tester) async {
+    await tester.pumpWidget(
+      new MaterialApp(
+        home: new Material(
+          child: new Center(
+            child: new RaisedButton(
+              onPressed: null,
+              child: new Text('Go'),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    BuildContext context = tester.element(find.text('Go'));
+
+    Future<int> result = showDialog(
+      context: context,
+      child: new SimpleDialog(
+        title: new Text('Title'),
+        children: <Widget>[
+          new SimpleDialogOption(
+            onPressed: () {
+              Navigator.pop(context, 42);
+            },
+            child: new Text('First option'),
+          ),
+          new SimpleDialogOption(
+            child: new Text('Second option'),
+          ),
+        ],
+      ),
+    );
+
+    await tester.pumpUntilNoTransientCallbacks(const Duration(seconds: 1));
+    expect(find.text('Title'), findsOneWidget);
+    await tester.tap(find.text('First option'));
+
+    expect(await result, equals(42));
+
+    // TODO(abarth): Remove once https://github.com/flutter/flutter/issues/7457
+    // is fixed.
+    await tester.pumpUntilNoTransientCallbacks(const Duration(seconds: 1));
+  });
 }

packages/flutter/test/material/ink_well_test.dart

@@ -0,0 +1,47 @@
+// Copyright 2016 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('InkWell gestures control test', (WidgetTester tester) async {
+    List<String> log = <String>[];
+
+    await tester.pumpWidget(new Material(
+      child: new Center(
+        child: new InkWell(
+          onTap: () {
+            log.add('tap');
+          },
+          onDoubleTap: () {
+            log.add('double-tap');
+          },
+          onLongPress: () {
+            log.add('long-press');
+          },
+        ),
+      ),
+    ));
+
+    await tester.tap(find.byType(InkWell), pointer: 1);
+
+    expect(log, isEmpty);
+
+    await tester.pump(const Duration(seconds: 1));
+
+    expect(log, equals(<String>['tap']));
+    log.clear();
+
+    await tester.tap(find.byType(InkWell), pointer: 2);
+    await tester.tap(find.byType(InkWell), pointer: 3);
+
+    expect(log, equals(<String>['double-tap']));
+    log.clear();
+
+    await tester.longPress(find.byType(InkWell), pointer: 4);
+
+    expect(log, equals(<String>['long-press']));
+  });
+}