feat: Added forceErrorText in DropdownButtonFormField #165188 (#165189)

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Feat: Added forceErrorText in DropdownButtonFormField #165188


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---------

Co-authored-by: Bruno Leroux <bruno.leroux@gmail.com>

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

@@ -1731,6 +1731,7 @@ class DropdownButtonFormField<T> extends FormField<T> {
     super.onSaved,
     super.validator,
     super.errorBuilder,
+    super.forceErrorText,
     AutovalidateMode? autovalidateMode,
     double? menuMaxHeight,
     bool? enableFeedback,

packages/flutter/test/material/dropdown_form_field_test.dart

@@ -1294,4 +1294,92 @@ void main() {
     await tester.pumpWidget(buildFrame(alignedDropdown: true, textDirection: TextDirection.rtl));
     expect(tester.getRect(findSelectedValue), contentRectForUnalignedDropdown);
   });
+
+  testWidgets('isValid returns false when forceErrorText is set and changes error display', (
+    WidgetTester tester,
+  ) async {
+    final GlobalKey<FormFieldState<String>> fieldKey1 = GlobalKey<FormFieldState<String>>();
+    final GlobalKey<FormFieldState<String>> fieldKey2 = GlobalKey<FormFieldState<String>>();
+    const String forceErrorText = 'Forcing error.';
+    await tester.pumpWidget(
+      MaterialApp(
+        home: MediaQuery(
+          data: const MediaQueryData(),
+          child: Directionality(
+            textDirection: TextDirection.ltr,
+            child: Center(
+              child: Material(
+                child: Form(
+                  child: ListView(
+                    children: <Widget>[
+                      DropdownButtonFormField<String>(
+                        key: fieldKey1,
+                        items:
+                            menuItems.map((String value) {
+                              return DropdownMenuItem<String>(value: value, child: Text(value));
+                            }).toList(),
+                        onChanged: null,
+                        autovalidateMode: AutovalidateMode.disabled,
+                      ),
+                      DropdownButtonFormField<String>(
+                        key: fieldKey2,
+                        items:
+                            menuItems.map((String value) {
+                              return DropdownMenuItem<String>(value: value, child: Text(value));
+                            }).toList(),
+                        forceErrorText: forceErrorText,
+                        onChanged: onChanged,
+                        autovalidateMode: AutovalidateMode.disabled,
+                      ),
+                    ],
+                  ),
+                ),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(fieldKey1.currentState!.isValid, isTrue);
+    expect(fieldKey1.currentState!.hasError, isFalse);
+    expect(fieldKey2.currentState!.isValid, isFalse);
+    expect(fieldKey2.currentState!.hasError, isTrue);
+  });
+
+  testWidgets('forceErrorText overrides InputDecoration.error when both are provided', (
+    WidgetTester tester,
+  ) async {
+    const String forceErrorText = 'Forcing error';
+    const String decorationErrorText = 'Decoration';
+
+    await tester.pumpWidget(
+      MaterialApp(
+        home: MediaQuery(
+          data: const MediaQueryData(),
+          child: Directionality(
+            textDirection: TextDirection.ltr,
+            child: Center(
+              child: Material(
+                child: Form(
+                  child: DropdownButtonFormField<String>(
+                    items:
+                        menuItems.map<DropdownMenuItem<String>>((String value) {
+                          return DropdownMenuItem<String>(value: value, child: Text(value));
+                        }).toList(),
+                    decoration: const InputDecoration(errorText: decorationErrorText),
+                    forceErrorText: forceErrorText,
+                    onChanged: null,
+                  ),
+                ),
+              ),
+            ),
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text(forceErrorText), findsOne);
+    expect(find.text(decorationErrorText), findsNothing);
+  });
 }