Fixed empty text of model selection button when no model is chosen

lib/screens/common_widgets/ai/ai_model_selector_button.dart

@@ -45,7 +45,9 @@ class AIModelSelectorButton extends StatelessWidget {
               if (newAIRequestModel == null) return;
               onModelUpdated?.call(newAIRequestModel);
             },
-      child: Text(aiRequestModel?.model ?? 'Select Model'),
+      child: Text((aiRequestModel?.model?.trim().isEmpty ?? true)
+          ? 'Select Model'
+          : aiRequestModel!.model!),
     );
   }
 }

test/screens/common_widgets/ai/ai_model_selector_button_test.dart

@@ -0,0 +1,55 @@
+import 'package:apidash/screens/common_widgets/ai/ai_model_selector_button.dart';
+import 'package:apidash_core/apidash_core.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  testWidgets('AIModelSelectorButton shows "Select Model" when model is null',
+      (WidgetTester tester) async {
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Scaffold(
+          body: AIModelSelectorButton(
+            aiRequestModel: null,
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Select Model'), findsOneWidget);
+  });
+
+  testWidgets(
+      'AIModelSelectorButton shows "Select Model" when model name is empty',
+      (WidgetTester tester) async {
+    const emptyModel = AIRequestModel(model: '', modelApiProvider: ModelAPIProvider.openai, apiKey: '');
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Scaffold(
+          body: AIModelSelectorButton(
+            aiRequestModel: emptyModel,
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('Select Model'), findsOneWidget);
+  });
+
+  testWidgets('AIModelSelectorButton shows model name when model is provided',
+      (WidgetTester tester) async {
+    const validModel = AIRequestModel(model: 'gpt-4', modelApiProvider: ModelAPIProvider.openai, apiKey: '');
+    await tester.pumpWidget(
+      const MaterialApp(
+        home: Scaffold(
+          body: AIModelSelectorButton(
+            aiRequestModel: validModel,
+          ),
+        ),
+      ),
+    );
+
+    expect(find.text('gpt-4'), findsOneWidget);
+    expect(find.text('Select Model'), findsNothing);
+  });
+}