fix: handle initialValue in OnscreenKeyboardTextFormField

packages/flutter_onscreen_keyboard/lib/src/onscreen_keyboard_text_form_field.dart

@@ -117,7 +117,10 @@ class OnscreenKeyboardTextFormField extends StatefulWidget {
         EditableText.defaultStylusHandwritingEnabled,
     this.canRequestFocus = true,
     this.hintLocales,
-  });
+  }) : assert(
+         initialValue == null || controller == null,
+         'Should not provide both an initialValue and a controller',
+       );
 
   /// This key is used to identify the form field when it is attached to the
   /// onscreen keyboard.
@@ -719,7 +722,8 @@ class _OnscreenKeyboardTextFormFieldState
     implements OnscreenKeyboardFieldState {
   /// The [TextEditingController] for the text field.
   TextEditingController get _effectiveController =>
-      widget.controller ?? (_controller ??= TextEditingController());
+      widget.controller ??
+      (_controller ??= TextEditingController(text: widget.initialValue));
   TextEditingController? _controller;
 
   /// The [FocusNode] for the text field.
@@ -779,7 +783,6 @@ class _OnscreenKeyboardTextFormFieldState
       groupId: widget.groupId,
       controller: _effectiveController,
       focusNode: _effectiveFocusNode,
-      initialValue: widget.initialValue,
       forceErrorText: widget.forceErrorText,
       decoration: widget.decoration,
       // prevent the keyboard from opening

packages/flutter_onscreen_keyboard/test/src/onscreen_keyboard_text_form_field_test.dart

@@ -161,5 +161,46 @@ void main() {
         expect(state.validate(), false);
       },
     );
+
+    test(
+      'should throw assertion error if '
+      'initialValue and controller are provided',
+      () {
+        expect(
+          () => OnscreenKeyboardTextFormField(
+            initialValue: 'initial',
+            controller: TextEditingController(),
+          ),
+          throwsA(
+            predicate(
+              (e) =>
+                  e is AssertionError &&
+                  e.message ==
+                      // ignore: lines_longer_than_80_chars
+                      'Should not provide both an initialValue and a controller',
+            ),
+          ),
+        );
+      },
+    );
+
+    testWidgets(
+      'initialValue in OnscreenKeyboardTextFormField',
+      (tester) async {
+        await tester.pumpWidget(
+          MaterialApp(
+            builder: OnscreenKeyboard.builder(width: (_) => 200),
+            home: const Scaffold(
+              body: OnscreenKeyboardTextFormField(
+                initialValue: 'initial value',
+              ),
+            ),
+          ),
+        );
+
+        await tester.pumpAndSettle();
+        expect(find.text('initial value'), findsOneWidget);
+      },
+    );
   });
 }