Typeahead fixes (#599)

* Added tests for FormBuilderTypeahead

* Fix issue: Typeahead change doesn't fire didChange & onChanged. Fixes #595

Also ensure programatically changed value propagates to UI and initialValue is set in UI after reset

Author: danvick

lib/src/fields/form_builder_typeahead.dart

@@ -325,8 +325,8 @@ class FormBuilderTypeAhead<T> extends FormBuilderField<T> {
                       ),
                 focusNode: state.effectiveFocusNode,
                 decoration: state.decoration(),
-              ) as TextFieldConfiguration<
-                  dynamic>, // HACK to satisfy strictness
+              ) as TextFieldConfiguration<dynamic>,
+              // HACK to satisfy strictness
               suggestionsCallback: suggestionsCallback,
               itemBuilder: itemBuilder,
               transitionBuilder: (context, suggestionsBox, controller) =>
@@ -339,9 +339,7 @@ class FormBuilderTypeAhead<T> extends FormBuilderField<T> {
                   state._typeAheadController.text =
                       suggestion != null ? suggestion.toString() : '';
                 }
-                if (onSuggestionSelected != null) {
-                  onSuggestionSelected(suggestion);
-                }
+                onSuggestionSelected?.call(suggestion);
               },
               getImmediateSuggestions: getImmediateSuggestions,
               errorBuilder: errorBuilder,
@@ -380,6 +378,29 @@ class _FormBuilderTypeAheadState<T>
     super.initState();
     _typeAheadController = widget.controller ??
         TextEditingController(text: widget.initialValue?.toString());
+    _typeAheadController.addListener(_handleControllerChanged);
+  }
+
+  void _handleControllerChanged() {
+    // Suppress changes that originated from within this class.
+    //
+    // In the case where a controller has been passed in to this widget, we
+    // register this change listener. In these cases, we'll also receive change
+    // notifications for changes originating from within this class -- for
+    // example, the reset() method. In such cases, the FormField value will
+    // already have been set.
+    if (_typeAheadController.text != value) {
+      didChange(_typeAheadController.text as T);
+    }
+  }
+
+  @override
+  void didChange(T value) {
+    super.didChange(value);
+
+    if (_typeAheadController.text != value) {
+      _typeAheadController.text = value.toString();
+    }
   }
 
   @override
@@ -394,6 +415,6 @@ class _FormBuilderTypeAheadState<T>
   @override
   void reset() {
     super.reset();
-    _typeAheadController.text = widget.initialValue?.toString();
+    _typeAheadController.text = initialValue?.toString();
   }
 }

test/fields/form_builder_typeahead_test.dart

@@ -0,0 +1,61 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_form_builder/flutter_form_builder.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import 'form_builder_tester.dart';
+
+void main() {
+  testWidgets('FormBuilderTypeahead -- Two', (WidgetTester tester) async {
+    const options = ['One', 'Two', 'Three', 'Four', 'Five', 'Six', 'Seven'];
+    const initialTextValue = 'One';
+    const newTextValue = 'Two';
+    const textFieldName = 'typeahead1';
+    final textEditingController = TextEditingController();
+    final testWidgetKey = GlobalKey<FormBuilderFieldState>();
+
+    final testWidget = FormBuilderTypeAhead<String>(
+      key: testWidgetKey,
+      name: textFieldName,
+      initialValue: initialTextValue,
+      controller: textEditingController,
+      itemBuilder: (context, country) {
+        return ListTile(title: Text(country));
+      },
+      suggestionsCallback: (query) {
+        if (query.isNotEmpty) {
+          var lowercaseQuery = query.toLowerCase();
+          return options.where((country) {
+            return country.toLowerCase().contains(lowercaseQuery);
+          }).toList(growable: false)
+            ..sort((a, b) => a
+                .toLowerCase()
+                .indexOf(lowercaseQuery)
+                .compareTo(b.toLowerCase().indexOf(lowercaseQuery)));
+        } else {
+          return options;
+        }
+      },
+    );
+    final widgetFinder = find.byWidget(testWidget);
+
+    await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+    expect(formSave(), isTrue);
+    expect(formValue(textFieldName), initialTextValue);
+
+    // await tester.enterText(widgetFinder, newTextValue);
+    textEditingController.text = newTextValue;
+    expect(formSave(), isTrue);
+    expect(formValue(textFieldName), equals(newTextValue));
+
+    // await tester.enterText(widgetFinder, newTextValue);
+    testWidgetKey.currentState.didChange(initialTextValue);
+    expect(textEditingController.text, initialTextValue);
+    expect(formSave(), isTrue);
+    expect(formValue(textFieldName), equals(initialTextValue));
+
+    // await tester.enterText(widgetFinder, '');
+    textEditingController.text = '';
+    expect(formSave(), isTrue);
+    expect(formValue(textFieldName), isEmpty);
+  });
+}