test: add tests for double tilde to strikethrough

frontend/app_flowy/packages/appflowy_editor/test/infra/test_raw_key_event.dart

@@ -139,6 +139,9 @@ extension on LogicalKeyboardKey {
     if (this == LogicalKeyboardKey.keyZ) {
       return PhysicalKeyboardKey.keyZ;
     }
+    if (this == LogicalKeyboardKey.tilde) {
+      return PhysicalKeyboardKey.backquote;
+    }
     throw UnimplementedError();
   }
 }

frontend/app_flowy/packages/appflowy_editor/test/service/internal_key_event_handlers/markdown_syntax_to_styled_text_test.dart

@@ -150,5 +150,111 @@ void main() async {
         expect(textNode.toRawString(), text);
       });
     });
+
+    group('convert double tilde to strikethrough', () {
+      Future<void> insertTilde(
+        EditorWidgetTester editor, {
+        int repeat = 1,
+      }) async {
+        for (var i = 0; i < repeat; i++) {
+          await editor.pressLogicKey(
+            LogicalKeyboardKey.tilde,
+            isShiftPressed: true,
+          );
+        }
+      }
+
+      testWidgets('~~AppFlowy~~ to strikethrough AppFlowy', (tester) async {
+        const text = '~~AppFlowy~';
+        final editor = tester.editor..insertTextNode('');
+        await editor.startTesting();
+        await editor.updateSelection(
+          Selection.single(path: [0], startOffset: 0),
+        );
+        final textNode = editor.nodeAtPath([0]) as TextNode;
+        for (var i = 0; i < text.length; i++) {
+          await editor.insertText(textNode, text[i], i);
+        }
+        await insertTilde(editor);
+        final allStrikethrough = textNode.allSatisfyStrikethroughInSelection(
+          Selection.single(
+            path: [0],
+            startOffset: 0,
+            endOffset: textNode.toRawString().length,
+          ),
+        );
+        expect(allStrikethrough, true);
+        expect(textNode.toRawString(), 'AppFlowy');
+      });
+
+      testWidgets('App~~Flowy~~ to strikethrough AppFlowy', (tester) async {
+        const text = 'App~~Flowy~';
+        final editor = tester.editor..insertTextNode('');
+        await editor.startTesting();
+        await editor.updateSelection(
+          Selection.single(path: [0], startOffset: 0),
+        );
+        final textNode = editor.nodeAtPath([0]) as TextNode;
+        for (var i = 0; i < text.length; i++) {
+          await editor.insertText(textNode, text[i], i);
+        }
+        await insertTilde(editor);
+        final allStrikethrough = textNode.allSatisfyStrikethroughInSelection(
+          Selection.single(
+            path: [0],
+            startOffset: 3,
+            endOffset: textNode.toRawString().length,
+          ),
+        );
+        expect(allStrikethrough, true);
+        expect(textNode.toRawString(), 'AppFlowy');
+      });
+
+      testWidgets('~~~AppFlowy~~ to bold ~AppFlowy', (tester) async {
+        const text = '~~~AppFlowy~';
+        final editor = tester.editor..insertTextNode('');
+        await editor.startTesting();
+        await editor.updateSelection(
+          Selection.single(path: [0], startOffset: 0),
+        );
+        final textNode = editor.nodeAtPath([0]) as TextNode;
+        for (var i = 0; i < text.length; i++) {
+          await editor.insertText(textNode, text[i], i);
+        }
+        await insertTilde(editor);
+        final allStrikethrough = textNode.allSatisfyStrikethroughInSelection(
+          Selection.single(
+            path: [0],
+            startOffset: 1,
+            endOffset: textNode.toRawString().length,
+          ),
+        );
+        expect(allStrikethrough, true);
+        expect(textNode.toRawString(), '~AppFlowy');
+      });
+
+      testWidgets('~~~~ nothing changes', (tester) async {
+        const text = '~~~';
+        final editor = tester.editor..insertTextNode('');
+        await editor.startTesting();
+        await editor.updateSelection(
+          Selection.single(path: [0], startOffset: 0),
+        );
+        final textNode = editor.nodeAtPath([0]) as TextNode;
+        for (var i = 0; i < text.length; i++) {
+          await editor.insertText(textNode, text[i], i);
+        }
+        await insertTilde(editor);
+        final allStrikethrough = textNode.allSatisfyStrikethroughInSelection(
+          Selection.single(
+            path: [0],
+            startOffset: 0,
+            endOffset: textNode.toRawString().length,
+          ),
+        );
+        expect(allStrikethrough, false);
+        expect(textNode.toRawString(), text);
+      });
+    });
   });
 }