feat: convert = and > to ⇒ (#523)

test/new/service/shortcuts/character_shortcut_events/double_characters_shortcut_events/format_equal_greater_test.dart

@@ -0,0 +1,64 @@
+import 'package:appflowy_editor/appflowy_editor.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+import '../../../../infra/testable_editor.dart';
+
+const _greater = '>';
+const _equals = '=';
+const _arrow = '⇒';
+
+void main() async {
+  group('format_equal_greater.dart', () {
+    testWidgets('= + > to ⇒ in empty paragraph', (tester) async {
+      final editor = tester.editor..addEmptyParagraph();
+      await editor.startTesting();
+
+      await editor.updateSelection(Selection.collapsed(Position(path: [0])));
+
+      await editor.ime.typeText(_equals);
+      await editor.ime.typeText(_greater);
+
+      final delta = editor.nodeAtPath([0])!.delta!;
+      expect(delta.length, 1);
+      expect(delta.toPlainText(), _arrow);
+
+      await editor.dispose();
+    });
+
+    testWidgets('= + > to ⇒ in non-empty paragraph, undo, redo',
+        (tester) async {
+      const text = 'Hello World';
+      final editor = tester.editor..addParagraph(initialText: text);
+      await editor.startTesting();
+
+      await editor.updateSelection(
+        Selection.collapsed(
+          Position(
+            path: [0],
+            offset: text.length,
+          ),
+        ),
+      );
+
+      await editor.ime.typeText(_equals);
+      await editor.ime.typeText(_greater);
+
+      Delta delta = editor.nodeAtPath([0])!.delta!;
+      expect(delta.toPlainText(), text + _arrow);
+
+      undoCommand.execute(editor.editorState);
+      await tester.pumpAndSettle();
+
+      delta = editor.nodeAtPath([0])!.delta!;
+      expect(delta.toPlainText(), text + _equals);
+
+      undoCommand.execute(editor.editorState);
+      await tester.pumpAndSettle();
+
+      delta = editor.nodeAtPath([0])!.delta!;
+      expect(delta.toPlainText(), text);
+
+      await editor.dispose();
+    });
+  });
+}