fix(auth): 登录异常改为居中吐司

test/core/centered_toast_test.dart

@@ -0,0 +1,93 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:fruitshorts/core/widgets/centered_toast.dart';
+
+void main() {
+  testWidgets('should_replace_previous_toast_when_shown_again', (tester) async {
+    late BuildContext hostContext;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Builder(
+          builder: (context) {
+            hostContext = context;
+            return const Scaffold(body: SizedBox.expand());
+          },
+        ),
+      ),
+    );
+
+    showCenteredToast(hostContext, 'first message');
+    await tester.pump();
+    showCenteredToast(hostContext, 'second message');
+    await tester.pump();
+
+    expect(find.byKey(const Key('centered-toast')), findsOneWidget);
+    expect(find.text('second message'), findsOneWidget);
+    expect(find.text('first message'), findsNothing);
+
+    await tester.pump(const Duration(seconds: 2));
+    await tester.pump(const Duration(milliseconds: 200));
+    expect(find.byKey(const Key('centered-toast')), findsNothing);
+  });
+
+  testWidgets('should_allow_underlying_gesture_when_toast_is_visible', (
+    tester,
+  ) async {
+    late BuildContext hostContext;
+    var taps = 0;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Builder(
+          builder: (context) {
+            hostContext = context;
+            return Scaffold(
+              body: GestureDetector(
+                key: const Key('toast-host'),
+                behavior: HitTestBehavior.opaque,
+                onTap: () => taps++,
+                child: const SizedBox.expand(),
+              ),
+            );
+          },
+        ),
+      ),
+    );
+    showCenteredToast(hostContext, 'tap-through');
+    await tester.pump();
+
+    await tester.tapAt(
+      tester.getCenter(find.byKey(const Key('centered-toast'))),
+    );
+
+    expect(taps, 1);
+    await tester.pump(const Duration(seconds: 2));
+    await tester.pump(const Duration(milliseconds: 200));
+  });
+
+  testWidgets('should_replace_toast_when_previous_toast_is_fading_out', (
+    tester,
+  ) async {
+    late BuildContext hostContext;
+    await tester.pumpWidget(
+      MaterialApp(
+        home: Builder(
+          builder: (context) {
+            hostContext = context;
+            return const Scaffold(body: SizedBox.expand());
+          },
+        ),
+      ),
+    );
+
+    showCenteredToast(hostContext, 'first message');
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 2));
+    showCenteredToast(hostContext, 'replacement message');
+    await tester.pump();
+
+    expect(tester.takeException(), isNull);
+    expect(find.text('replacement message'), findsOneWidget);
+    await tester.pump(const Duration(seconds: 3));
+    await tester.pumpAndSettle();
+  });
+}