Reland text state (#47464)

packages/flutter/test/material/text_field_test.dart

@@ -2961,7 +2961,7 @@ void main() {
         ),
       ),
     );
-    expect(tester.testTextInput.editingState['text'], isEmpty);
+    expect(tester.testTextInput.editingState, isNull);
 
     // Initial state with null controller.
     await tester.tap(find.byType(TextField));

packages/flutter/test/widgets/editable_text_test.dart

@@ -3928,10 +3928,6 @@ void main() {
   });
 
   testWidgets('input imm channel calls are ordered correctly', (WidgetTester tester) async {
-    final List<MethodCall> log = <MethodCall>[];
-    SystemChannels.textInput.setMockMethodCallHandler((MethodCall methodCall) async {
-      log.add(methodCall);
-    });
     const String testText = 'flutter is the best!';
     final TextEditingController controller = TextEditingController(text: testText);
     final EditableText et = EditableText(
@@ -3956,14 +3952,107 @@ void main() {
     ));
 
     await tester.showKeyboard(find.byType(EditableText));
-    expect(log.length, 7);
     // TextInput.show should be before TextInput.setEditingState
     final List<String> logOrder = <String>['TextInput.setClient', 'TextInput.show', 'TextInput.setEditableSizeAndTransform', 'TextInput.setStyle', 'TextInput.setEditingState', 'TextInput.setEditingState', 'TextInput.show'];
+    expect(tester.testTextInput.log.length, 7);
+    int index = 0;
+    for (MethodCall m in tester.testTextInput.log) {
+      expect(m.method, logOrder[index]);
+      index++;
+    }
+  });
+
+  testWidgets('setEditingState is not called when text changes', (WidgetTester tester) async {
+    // We shouldn't get a message here because this change is owned by the platform side.
+    const String testText = 'flutter is the best!';
+    final TextEditingController controller = TextEditingController(text: testText);
+    final EditableText et = EditableText(
+      showSelectionHandles: true,
+      maxLines: 2,
+      controller: controller,
+      focusNode: FocusNode(),
+      cursorColor: Colors.red,
+      backgroundCursorColor: Colors.blue,
+      style: Typography(platform: TargetPlatform.android).black.subhead.copyWith(fontFamily: 'Roboto'),
+      keyboardType: TextInputType.text,
+    );
+
+    await tester.pumpWidget(MaterialApp(
+      home: Align(
+        alignment: Alignment.topLeft,
+        child: SizedBox(
+          width: 100,
+          child: et,
+        ),
+      ),
+    ));
+
+    await tester.enterText(find.byType(EditableText), '...');
+
+    final List<String> logOrder = <String>[
+      'TextInput.setClient',
+      'TextInput.show',
+      'TextInput.setEditableSizeAndTransform',
+      'TextInput.setStyle',
+      'TextInput.setEditingState',
+      'TextInput.setEditingState',
+      'TextInput.show',
+    ];
+    expect(tester.testTextInput.log.length, logOrder.length);
+    int index = 0;
+    for (MethodCall m in tester.testTextInput.log) {
+      expect(m.method, logOrder[index]);
+      index++;
+    }
+    expect(tester.testTextInput.editingState['text'], 'flutter is the best!');
+  });
+
+  testWidgets('setEditingState is called when text changes on controller', (WidgetTester tester) async {
+    // We should get a message here because this change is owned by the framework side.
+    const String testText = 'flutter is the best!';
+    final TextEditingController controller = TextEditingController(text: testText);
+    final EditableText et = EditableText(
+      showSelectionHandles: true,
+      maxLines: 2,
+      controller: controller,
+      focusNode: FocusNode(),
+      cursorColor: Colors.red,
+      backgroundCursorColor: Colors.blue,
+      style: Typography(platform: TargetPlatform.android).black.subhead.copyWith(fontFamily: 'Roboto'),
+      keyboardType: TextInputType.text,
+    );
+
+    await tester.pumpWidget(MaterialApp(
+      home: Align(
+        alignment: Alignment.topLeft,
+        child: SizedBox(
+          width: 100,
+          child: et,
+        ),
+      ),
+    ));
+
+    await tester.showKeyboard(find.byType(EditableText));
+    controller.text += '...';
+    await tester.idle();
+
+    final List<String> logOrder = <String>[
+      'TextInput.setClient',
+      'TextInput.show',
+      'TextInput.setEditableSizeAndTransform',
+      'TextInput.setStyle',
+      'TextInput.setEditingState',
+      'TextInput.setEditingState',
+      'TextInput.show',
+      'TextInput.setEditingState',
+    ];
+    expect(tester.testTextInput.log.length, logOrder.length);
     int index = 0;
-    for (MethodCall m in log) {
+    for (MethodCall m in tester.testTextInput.log) {
       expect(m.method, logOrder[index]);
       index++;
     }
+    expect(tester.testTextInput.editingState['text'], 'flutter is the best!...');
   });
 }
 

packages/flutter_test/lib/src/test_text_input.dart

@@ -39,6 +39,18 @@ class TestTextInput {
   /// The messenger which sends the bytes for this channel, not null.
   BinaryMessenger get _binaryMessenger => ServicesBinding.instance.defaultBinaryMessenger;
 
+  /// Resets any internal state of this object and calls [register].
+  ///
+  /// This method is invoked by the testing framework between tests. It should
+  /// not ordinarily be called by tests directly.
+  void resetAndRegister() {
+    log.clear();
+    editingState = null;
+    setClientArgs = null;
+    _client = 0;
+    _isVisible = false;
+    register();
+  }
   /// Installs this object as a mock handler for [SystemChannels.textInput].
   void register() {
     SystemChannels.textInput.setMockMethodCallHandler(_handleTextInputCall);
@@ -64,6 +76,7 @@ class TestTextInput {
   /// Whether this [TestTextInput] is registered with [SystemChannels.textInput].
   ///
   /// Use [register] and [unregister] methods to control this value.
+  // TODO(dnfield): This is unreliable. https://github.com/flutter/flutter/issues/47180
   bool get isRegistered => _isRegistered;
   bool _isRegistered = false;
 

packages/flutter_test/lib/src/widget_tester.dart

@@ -121,6 +121,7 @@ void testWidgets(
       return binding.runTest(
         () async {
           debugResetSemanticsIdCounter();
+          tester.resetTestTextInput();
           await callback(tester);
           semanticsHandle?.dispose();
         },
@@ -692,6 +693,17 @@ class WidgetTester extends WidgetController implements HitTestDispatcher, Ticker
   /// like [TextField] or [TextFormField], call [enterText].
   TestTextInput get testTextInput => binding.testTextInput;
 
+  /// Ensures that [testTextInput] is registered and [TestTextInput.log] is
+  /// reset.
+  ///
+  /// This is called by the testing framework before test runs, so that if a
+  /// previous test has set its own handler on [SystemChannels.textInput], the
+  /// [testTextInput] regains control and the log is fresh for the new test.
+  /// It should not typically need to be called by tests.
+  void resetTestTextInput() {
+    testTextInput.resetAndRegister();
+  }
+
   /// Give the text input widget specified by [finder] the focus, as if the
   /// onscreen keyboard had appeared.
   ///