[animations] Add ability to use root Navigator with an OpenContainer

packages/animations/lib/src/open_container.dart

@@ -72,6 +72,7 @@ class OpenContainer extends StatefulWidget {
     this.tappable = true,
     this.transitionDuration = const Duration(milliseconds: 300),
     this.transitionType = ContainerTransitionType.fade,
+    this.useRootNavigator = false,
   })  : assert(closedColor != null),
         assert(openColor != null),
         assert(closedElevation != null),
@@ -82,6 +83,7 @@ class OpenContainer extends StatefulWidget {
         assert(openBuilder != null),
         assert(tappable != null),
         assert(transitionType != null),
+        assert(useRootNavigator != null),
         super(key: key);
 
   /// Background color of the container while it is closed.
@@ -207,6 +209,14 @@ class OpenContainer extends StatefulWidget {
   /// Defaults to [ContainerTransitionType.fade].
   final ContainerTransitionType transitionType;
 
+  /// The [useRootNavigator] argument is used to determine whether to push the
+  /// route for [openBuilder] to the Navigator furthest from or nearest to
+  /// the given context.
+  ///
+  /// By default, [useRootNavigator] is false and the route created will push
+  /// to the nearest navigator.
+  final bool useRootNavigator;
+
   @override
   _OpenContainerState createState() => _OpenContainerState();
 }
@@ -224,8 +234,9 @@ class _OpenContainerState extends State<OpenContainer> {
   // same widget included in the [_OpenContainerRoute] where it fades out.
   final GlobalKey _closedBuilderKey = GlobalKey();
 
-  Future<void> openContainer<T>() async {
-    await Navigator.of(context).push(_OpenContainerRoute(
+  Future<void> openContainer() async {
+    await Navigator.of(context, rootNavigator: widget.useRootNavigator)
+        .push(_OpenContainerRoute(
       closedColor: widget.closedColor,
       openColor: widget.openColor,
       closedElevation: widget.closedElevation,

packages/animations/test/open_container_test.dart

@@ -1110,6 +1110,7 @@ void main() {
         ),
       ),
     ));
+
     await tester.tap(find.text('Closed'));
     await tester.pumpAndSettle();
 
@@ -1448,6 +1449,7 @@ void main() {
     expect(find.text('Closed 2'), findsNothing);
     expect(find.text('Open 2'), findsOneWidget);
   });
+
   testWidgets('onClosed callback is called when container has closed',
       (WidgetTester tester) async {
     bool hasClosed = false;
@@ -1490,6 +1492,80 @@ void main() {
     expect(find.text('Closed'), findsOneWidget);
     expect(hasClosed, isTrue);
   });
+
+  Widget _createRootNavigatorTest({
+    @required Key appKey,
+    @required Key nestedNavigatorKey,
+    @required bool useRootNavigator,
+  }) {
+    return MaterialApp(
+        key: appKey,
+        // a nested navigator
+        home: Navigator(
+            key: nestedNavigatorKey,
+            onGenerateRoute: (RouteSettings route) {
+              return MaterialPageRoute<dynamic>(
+                  settings: route,
+                  builder: (BuildContext context) {
+                    return Container(
+                        child: OpenContainer(
+                            useRootNavigator: useRootNavigator,
+                            closedBuilder: (BuildContext context, _) {
+                              return const Text('Closed');
+                            },
+                            openBuilder: (BuildContext context, _) {
+                              return const Text('Opened');
+                            }));
+                  });
+            }));
+  }
+
+  testWidgets(
+      'Verify that "useRootNavigator: false" uses the correct navigator',
+      (WidgetTester tester) async {
+    const Key appKey = Key('App');
+    const Key nestedNavigatorKey = Key('Nested Navigator');
+
+    await tester.pumpWidget(_createRootNavigatorTest(
+        appKey: appKey,
+        nestedNavigatorKey: nestedNavigatorKey,
+        useRootNavigator: false));
+
+    await tester.tap(find.text('Closed'));
+    await tester.pumpAndSettle();
+
+    expect(
+        find.descendant(of: find.byKey(appKey), matching: find.text('Opened')),
+        findsOneWidget);
+
+    expect(
+        find.descendant(
+            of: find.byKey(nestedNavigatorKey), matching: find.text('Opened')),
+        findsOneWidget);
+  });
+
+  testWidgets('Verify that "useRootNavigator: true" uses the correct navigator',
+      (WidgetTester tester) async {
+    const Key appKey = Key('App');
+    const Key nestedNavigatorKey = Key('Nested Navigator');
+
+    await tester.pumpWidget(_createRootNavigatorTest(
+        appKey: appKey,
+        nestedNavigatorKey: nestedNavigatorKey,
+        useRootNavigator: true));
+
+    await tester.tap(find.text('Closed'));
+    await tester.pumpAndSettle();
+
+    expect(
+        find.descendant(of: find.byKey(appKey), matching: find.text('Opened')),
+        findsOneWidget);
+
+    expect(
+        find.descendant(
+            of: find.byKey(nestedNavigatorKey), matching: find.text('Opened')),
+        findsNothing);
+  });
 }
 
 Color _getScrimColor(WidgetTester tester) {