Gallery Smoke Test (#3446)

* Gallery Smoke Test

examples/material_gallery/lib/demo/page_selector_demo.dart

@@ -40,14 +40,14 @@ class PageSelectorDemo extends StatelessWidget {
                         icon: Icons.arrow_back,
                         color: color,
                         onPressed: () { _handleArrowButtonPress(context, -1); },
-                        tooltip: 'Back'
+                        tooltip: 'Page back'
                       ),
                       new TabPageSelector<IconData>(),
                       new IconButton(
                         icon: Icons.arrow_forward,
                         color: color,
                         onPressed: () { _handleArrowButtonPress(context, 1); },
-                        tooltip: 'Forward'
+                        tooltip: 'Page forward'
                       )
                     ],
                     mainAxisAlignment: MainAxisAlignment.spaceBetween

examples/material_gallery/lib/gallery/home.dart

@@ -93,7 +93,7 @@ class GalleryHomeState extends State<GalleryHome> {
       appBar: new AppBar(
         expandedHeight: _kFlexibleSpaceMaxHeight,
         flexibleSpace: new FlexibleSpaceBar(
-          title: new Text("Flutter gallery"),
+          title: new Text('Flutter gallery'),
           background: new GalleryHeader()
         )
       ),
@@ -104,18 +104,18 @@ class GalleryHomeState extends State<GalleryHome> {
         children: <Widget>[
           new TwoLevelSublist(
             leading: new Icon(icon: Icons.star),
-            title: new Text("Demos"),
+            title: new Text('Demos'),
             children: <Widget>[
-              new GalleryItem(title: "Weather", builder: () => new WeatherDemo()),
-              new GalleryItem(title: "Fitness", builder: () => new FitnessDemo()),
-              new GalleryItem(title: "Fancy lines", builder: () => new DrawingDemo()),
+              new GalleryItem(title: 'Weather', builder: () => new WeatherDemo()),
+              new GalleryItem(title: 'Fitness', builder: () => new FitnessDemo()),
+              new GalleryItem(title: 'Fancy lines', builder: () => new DrawingDemo()),
               new GalleryItem(title: 'Flexible space toolbar', builder: () => new FlexibleSpaceDemo()),
               new GalleryItem(title: 'Floating action button', builder: () => new TabsFabDemo()),
             ]
           ),
           new TwoLevelSublist(
             leading: new Icon(icon: Icons.extension),
-            title: new Text("Components"),
+            title: new Text('Components'),
             children: <Widget>[
               new GalleryItem(title: 'Buttons', builder: () => new ButtonsDemo()),
               new GalleryItem(title: 'Cards', builder: () => new CardsDemo()),
@@ -147,7 +147,7 @@ class GalleryHomeState extends State<GalleryHome> {
           ),
           new TwoLevelSublist(
             leading: new Icon(icon: Icons.color_lens),
-            title: new Text("Style"),
+            title: new Text('Style'),
             children: <Widget>[
               new GalleryItem(title: 'Colors', builder: () => new ColorsDemo()),
               new GalleryItem(title: 'Typography', builder: () => new TypographyDemo()),

examples/material_gallery/test/smoke_test.dart

@@ -8,6 +8,77 @@ import 'package:test/test.dart';
 
 import '../lib/main.dart' as material_gallery;
 
+// Warning: the following strings must be kept in sync with GalleryHome.
+const List<String> demoCategories = const <String>['Demos', 'Components', 'Style'];
+const List<String> demoNames = const <String>[
+  'Weather',
+  'Fitness',
+  'Fancy lines',
+  'Flexible space toolbar',
+  'Floating action button',
+  'Buttons',
+  'Cards',
+  'Chips',
+  'Date picker',
+  'Data tables',
+  'Dialog',
+  'Drop-down button',
+  'Expand/collapse list control',
+  'Grid',
+  'Icons',
+  'Leave-behind list items',
+  'List',
+  'Menus',
+  'Modal bottom sheet',
+  'Over-scroll',
+  'Page selector',
+  'Persistent bottom sheet',
+  'Progress indicators',
+  'Scrollable tabs',
+  'Selection controls',
+  'Sliders',
+  'Snackbar',
+  'Tabs',
+  'Text fields',
+  'Time picker',
+  'Tooltips',
+  'Colors',
+  'Typography'
+];
+
+Finder byTooltip(WidgetTester tester, String message) {
+  return find.byElement((Element element) {
+    Widget widget = element.widget;
+    if (widget is Tooltip)
+      return widget.message == message;
+    return false;
+  });
+}
+
+Finder findNavigationMenuButton(WidgetTester tester) => byTooltip(tester, 'Open navigation menu');
+
+Finder findBackButton(WidgetTester tester) => byTooltip(tester, 'Back');
+
+// Start a gallery demo and then go back. This function assumes that the
+// we're starting on home route and that the submenu that contains the demo
+// called 'name' is already open.
+void smokeDemo(WidgetTester tester, String menuItemText) {
+  // Ensure that we're (likely to be) on the home page
+  final Finder navigationMenuButton = findNavigationMenuButton(tester);
+  expect(tester, hasWidget(navigationMenuButton));
+
+  tester.tap(find.text(menuItemText));
+  tester.pump(); // Launch the demo.
+  tester.pump(const Duration(seconds: 1)); // Wait until the demo has opened.
+
+  // Go back
+  Finder backButton = findBackButton(tester);
+  expect(tester, hasWidget(backButton));
+  tester.tap(backButton);
+  tester.pump(); // Start the navigator pop "back" operation.
+  tester.pump(const Duration(seconds: 1)); // Wait until it has finished.
+}
+
 void main() {
   test('Material Gallery app smoke test', () {
     testWidgets((WidgetTester tester) {
@@ -15,48 +86,45 @@ void main() {
       tester.pump(); // see https://github.com/flutter/flutter/issues/1865
       tester.pump(); // triggers a frame
 
-      // Try loading Weather demo
-      tester.tap(find.text('Demos'));
-      tester.pump();
-      tester.pump(const Duration(seconds: 1)); // wait til it's really opened
+      // Expand the demo category submenus.
+      for (String category in demoCategories.reversed) {
+        tester.tap(find.text(category));
+        tester.pump();
+        tester.pump(const Duration(seconds: 1)); // Wait until the menu has expanded.
+      }
 
-      tester.tap(find.text('Weather'));
-      tester.pump();
-      tester.pump(const Duration(seconds: 1)); // wait til it's really opened
-
-      // Go back
-      Finder backButton = find.byElement((Element element) {
-        Widget widget = element.widget;
-        if (widget is Tooltip)
-          return widget.message == 'Back';
-        return false;
-      });
-      expect(tester, hasWidget(backButton));
-      tester.tap(backButton);
-      tester.pump(); // start going back
-      tester.pump(const Duration(seconds: 1)); // wait til it's finished
-
-      // Open menu
-      Finder navigationMenu = find.byElement((Element element) {
-        Widget widget = element.widget;
-        if (widget is Tooltip)
-          return widget.message == 'Open navigation menu';
-        return false;
-      });
-      expect(tester, hasWidget(navigationMenu));
-      tester.tap(navigationMenu);
-      tester.pump(); // start opening menu
-      tester.pump(const Duration(seconds: 1)); // wait til it's really opened
+      final List<double> scrollDeltas = new List<double>();
+      double previousY = tester.getTopRight(find.text(demoCategories[0])).y;
+      for (String name in demoNames) {
+        final double y = tester.getTopRight(find.text(name)).y;
+        scrollDeltas.add(previousY - y);
+        previousY = y;
+      }
+
+      // Launch each demo and then scroll that item out of the way.
+      for (int i = 0; i < demoNames.length; i += 1) {
+        final String name = demoNames[i];
+        print("$name");
+        smokeDemo(tester, name);
+        tester.scroll(find.text(name), new Offset(0.0, scrollDeltas[i]));
+        tester.pump();
+      }
+
+      Finder navigationMenuButton = findNavigationMenuButton(tester);
+      expect(tester, hasWidget(navigationMenuButton));
+      tester.tap(navigationMenuButton);
+      tester.pump(); // Start opening drawer.
+      tester.pump(const Duration(seconds: 1)); // Wait until it's really opened.
 
       // switch theme
       tester.tap(find.text('Dark'));
       tester.pump();
-      tester.pump(const Duration(seconds: 1)); // wait til it's changed
+      tester.pump(const Duration(seconds: 1)); // Wait until it's changed.
 
       // switch theme
       tester.tap(find.text('Light'));
       tester.pump();
-      tester.pump(const Duration(seconds: 1)); // wait til it's changed
+      tester.pump(const Duration(seconds: 1)); // Wait until it's changed.
     });
   });
 }

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

@@ -215,7 +215,7 @@ class Scaffold extends StatefulWidget {
     this.scrollableKey,
     this.appBarBehavior: AppBarBehavior.anchor
   }) : super(key: key) {
-    assert((appBarBehavior == AppBarBehavior.scroll) ? scrollableKey != null : true);
+    assert(scrollableKey != null ? (appBarBehavior != AppBarBehavior.anchor) : true);
   }
 
   final AppBar appBar;