diff --git a/client/test/responsive/form_factor_test.dart b/client/test/responsive/form_factor_test.dart
new file mode 100644
index 0000000..987a3e3
--- /dev/null
+++ b/client/test/responsive/form_factor_test.dart
@@ -0,0 +1,27 @@
+import 'package:flutter/widgets.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:pangolin_vpn/core/responsive/form_factor.dart';
+
+Future<FormFactor> _ffAt(WidgetTester tester, Size size) async {
+  late FormFactor ff;
+  tester.view.physicalSize = size;
+  tester.view.devicePixelRatio = 1.0;
+  addTearDown(tester.view.reset);
+  await tester.pumpWidget(MediaQuery(
+    data: MediaQueryData.fromView(tester.view),
+    child: Builder(builder: (c) { ff = c.formFactor; return const SizedBox(); }),
+  ));
+  return ff;
+}
+
+void main() {
+  testWidgets('iPad 竖屏(768) → tablet', (t) async {
+    expect(await _ffAt(t, const Size(768, 1024)), FormFactor.tablet);
+  });
+  testWidgets('iPad 横屏(1024) → tablet', (t) async {
+    expect(await _ffAt(t, const Size(1024, 768)), FormFactor.tablet);
+  });
+  testWidgets('iPhone(390) → mobile', (t) async {
+    expect(await _ffAt(t, const Size(390, 844)), FormFactor.mobile);
+  });
+}