feat: import Chinese-localized Buzz source snapshot

Signed-off-by: cls_宁波本机 <908705107@qq.com>

mobile/test/shared/widgets/keyboard_dismiss_on_drag_test.dart

@@ -0,0 +1,159 @@
+import 'package:buzz/shared/widgets/keyboard_dismiss_on_drag.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+/// A focused field inside a `Scaffold` body, which is the only arrangement
+/// either message list ever runs in.
+Widget _testable({
+  required FocusNode focusNode,
+  VoidCallback? onUserScrollStart,
+}) {
+  return MaterialApp(
+    home: Scaffold(
+      body: Column(
+        children: [
+          TextField(focusNode: focusNode),
+          Expanded(
+            child: KeyboardDismissOnDrag(
+              onUserScrollStart: onUserScrollStart,
+              child: ListView(
+                children: [
+                  for (var i = 0; i < 40; i++)
+                    SizedBox(height: 60, child: Text('row $i')),
+                ],
+              ),
+            ),
+          ),
+        ],
+      ),
+    ),
+  );
+}
+
+/// Raise the keyboard the way the platform does — on the view, not via a
+/// synthetic `MediaQuery` wrapper. It has to travel the real path, because
+/// `Scaffold` strips the bottom view inset from its body once it has resized to
+/// account for it, and that stripping is the whole reason this widget broke.
+void _raiseKeyboard(WidgetTester tester) {
+  tester.view.viewInsets = const FakeViewPadding(bottom: 300);
+  addTearDown(tester.view.reset);
+}
+
+Future<void> _dragDown(
+  WidgetTester tester,
+  double distance, {
+  String on = 'row 3',
+}) async {
+  final gesture = await tester.startGesture(tester.getCenter(find.text(on)));
+  // Several small moves, the way a real finger reports — the accumulator has to
+  // add them up rather than needing one big delta.
+  final step = distance / 6;
+  for (var i = 0; i < 6; i++) {
+    await gesture.moveBy(Offset(0, step));
+    await tester.pump();
+  }
+  await gesture.up();
+  await tester.pump();
+}
+
+void main() {
+  group('KeyboardDismissOnDrag', () {
+    testWidgets('a deliberate downward drag drops focus', (tester) async {
+      final focusNode = FocusNode();
+      addTearDown(focusNode.dispose);
+      _raiseKeyboard(tester);
+      await tester.pumpWidget(_testable(focusNode: focusNode));
+      focusNode.requestFocus();
+      await tester.pump();
+      expect(focusNode.hasFocus, isTrue);
+
+      await _dragDown(tester, keyboardDismissDragThreshold * 2);
+
+      // At rest the list can't scroll down, so this gesture is pure overscroll
+      // — the case that reports `OverscrollNotification` rather than
+      // `ScrollUpdateNotification`, and the one a focused composer is usually
+      // sitting in.
+      expect(focusNode.hasFocus, isFalse);
+    });
+
+    testWidgets('an ordinary downward scroll dismisses too', (tester) async {
+      final focusNode = FocusNode();
+      addTearDown(focusNode.dispose);
+      _raiseKeyboard(tester);
+      await tester.pumpWidget(_testable(focusNode: focusNode));
+      focusNode.requestFocus();
+      await tester.pump();
+
+      // Move off the resting edge so dragging down actually moves the position,
+      // covering the `ScrollUpdateNotification` path rather than overscroll.
+      await tester.drag(find.text('row 3'), const Offset(0, -400));
+      await tester.pumpAndSettle();
+      expect(focusNode.hasFocus, isTrue);
+
+      await _dragDown(tester, keyboardDismissDragThreshold * 2, on: 'row 10');
+
+      expect(focusNode.hasFocus, isFalse);
+    });
+
+    testWidgets('a short scroll leaves the keyboard alone', (tester) async {
+      final focusNode = FocusNode();
+      addTearDown(focusNode.dispose);
+      _raiseKeyboard(tester);
+      await tester.pumpWidget(_testable(focusNode: focusNode));
+      focusNode.requestFocus();
+      await tester.pump();
+
+      await _dragDown(tester, keyboardDismissDragThreshold / 2);
+
+      expect(focusNode.hasFocus, isTrue);
+    });
+
+    testWidgets('reports a user-started scroll', (tester) async {
+      final focusNode = FocusNode();
+      addTearDown(focusNode.dispose);
+      var userScrollStarts = 0;
+      await tester.pumpWidget(
+        _testable(
+          focusNode: focusNode,
+          onUserScrollStart: () => userScrollStarts += 1,
+        ),
+      );
+
+      await tester.drag(find.text('row 3'), const Offset(0, -100));
+      await tester.pumpAndSettle();
+
+      expect(userScrollStarts, 1);
+    });
+
+    testWidgets('an upward drag never dismisses, however far it goes', (
+      tester,
+    ) async {
+      final focusNode = FocusNode();
+      addTearDown(focusNode.dispose);
+      _raiseKeyboard(tester);
+      await tester.pumpWidget(_testable(focusNode: focusNode));
+      focusNode.requestFocus();
+      await tester.pump();
+
+      await _dragDown(tester, -keyboardDismissDragThreshold * 4);
+
+      expect(focusNode.hasFocus, isTrue);
+    });
+
+    testWidgets('with the keyboard already down, focus is left as it is', (
+      tester,
+    ) async {
+      final focusNode = FocusNode();
+      addTearDown(focusNode.dispose);
+      // No _raiseKeyboard: the keyboard is down.
+      await tester.pumpWidget(_testable(focusNode: focusNode));
+      focusNode.requestFocus();
+      await tester.pump();
+
+      await _dragDown(tester, keyboardDismissDragThreshold * 2);
+
+      // Nothing to dismiss, so don't yank focus out of whatever holds it.
+      expect(focusNode.hasFocus, isTrue);
+    });
+  });
+}