test: Add reset custom error test

Author: deandreamatias

test/form_builder_tester.dart

@@ -1,7 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:flutter_form_builder/flutter_form_builder.dart';
 
-final _formKey = GlobalKey<FormBuilderState>();
+final formKey = GlobalKey<FormBuilderState>();
 
 Widget buildTestableFieldWidget(
   Widget widget, {
@@ -11,7 +11,7 @@ Widget buildTestableFieldWidget(
   return MaterialApp(
     home: Scaffold(
       body: FormBuilder(
-        key: _formKey,
+        key: formKey,
         initialValue: initialValue,
         clearValueOnUnregister: clearValueOnUnregister,
         child: widget,
@@ -20,10 +20,10 @@ Widget buildTestableFieldWidget(
   );
 }
 
-bool formSave() => _formKey.currentState!.saveAndValidate();
+bool formSave() => formKey.currentState!.saveAndValidate();
 void formFieldDidChange(String fieldName, dynamic value) {
-  _formKey.currentState!.fields[fieldName]!.didChange(value);
+  formKey.currentState!.fields[fieldName]!.didChange(value);
 }
 
-T formValue<T>(String name) => _formKey.currentState!.value[name];
-T formInstantValue<T>(String name) => _formKey.currentState!.instantValue[name];
+T formValue<T>(String name) => formKey.currentState!.value[name];
+T formInstantValue<T>(String name) => formKey.currentState!.instantValue[name];

test/src/form_builder_field_test.dart

@@ -0,0 +1,47 @@
+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() {
+  group('Form Builder Field -', () {
+    testWidgets('Reset custom error from form builder', (tester) async {
+      const textFieldName = 'text1';
+      const errorTextField = 'error text field';
+      final testWidget = FormBuilderTextField(name: textFieldName);
+      await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+
+      // Set custom error
+      formKey.currentState
+          ?.invalidateField(name: textFieldName, errorText: errorTextField);
+      await tester.pumpAndSettle();
+      expect(find.text(errorTextField), findsOneWidget);
+
+      // Reset custom error
+      formKey.currentState?.reset();
+      await tester.pumpAndSettle();
+      expect(find.text(errorTextField), findsNothing);
+    });
+    testWidgets('Reset custom error from form builder field', (tester) async {
+      final textFieldKey = GlobalKey<FormBuilderFieldState>();
+      const textFieldName = 'text2';
+      const errorTextField = 'error text field';
+      final testWidget = FormBuilderTextField(
+        name: textFieldName,
+        key: textFieldKey,
+      );
+      await tester.pumpWidget(buildTestableFieldWidget(testWidget));
+
+      // Set custom error
+      textFieldKey.currentState?.invalidate(errorTextField);
+      await tester.pumpAndSettle();
+      expect(find.text(errorTextField), findsOneWidget);
+
+      // Reset custom error
+      textFieldKey.currentState?.reset();
+      await tester.pumpAndSettle();
+      expect(find.text(errorTextField), findsNothing);
+    });
+  });
+}