[SuperEditor][Web] - Fix backspace to un-indent (Resolves #2456) (#2545)

Author: angelosilvestre

super_editor/lib/src/default_editor/super_editor.dart

@@ -1436,18 +1436,22 @@ final defaultImeKeyboardActions = <DocumentKeyboardAction>[
   selectAllWhenCmdAIsPressed,
   cmdBToToggleBold,
   cmdIToToggleItalics,
+  // All handlers that use backspace should be placed before `doNothingWithBackspaceOnWeb`,
+  // otherwise they will not run on web.
+  backspaceToUnIndentListItem,
+  backspaceToUnIndentParagraph,
+  backspaceToUnIndentTask,
+  backspaceToConvertTaskToParagraph,
+  backspaceToClearParagraphBlockType,
+  // We handled all shortcuts that care about backspace. Let the browser IME handle the
+  // backspace to perform text deletion.
   doNothingWithBackspaceOnWeb,
   doNothingWithCtrlOrCmdAndZOnWeb,
   tabToIndentTask,
   shiftTabToUnIndentTask,
-  backspaceToUnIndentTask,
   tabToIndentParagraph,
   shiftTabToUnIndentParagraph,
-  backspaceToUnIndentParagraph,
-  backspaceToConvertTaskToParagraph,
-  backspaceToUnIndentListItem,
   enterToUnIndentParagraph,
-  backspaceToClearParagraphBlockType,
   deleteDownstreamCharacterWithCtrlDeleteOnMac,
   scrollOnCtrlOrCmdAndHomeKeyPress,
   scrollOnCtrlOrCmdAndEndKeyPress,

super_editor/test/super_editor/components/list_items_test.dart

@@ -8,6 +8,7 @@ import 'package:super_editor/super_editor.dart';
 import 'package:super_editor/super_editor_test.dart';
 import 'package:super_text_layout/super_text_layout.dart';
 
+import '../../test_runners.dart';
 import '../supereditor_test_tools.dart';
 
 void main() {
@@ -328,6 +329,24 @@ void main() {
         expect(doc.last.asListItem.indent, 0);
       });
 
+      testWidgetsOnDesktopAndWeb('unindents with BACKSPACE with caret at beginning of list item', (tester) async {
+        await _pumpUnorderedListWithTextField(tester);
+
+        final doc = SuperEditorInspector.findDocument()!;
+
+        // Place caret at the last list item, which has two levels of indentation.
+        await tester.placeCaretInParagraph(doc.last.id, 0);
+
+        // Ensure the list item has second level of indentation.
+        expect(doc.last.asListItem.indent, 1);
+
+        // Press BACKSPACE to trigger the list unindent command.
+        await tester.pressBackspace();
+
+        // Ensure the list item has first level of indentation.
+        expect(doc.last.asListItem.indent, 0);
+      });
+
       testWidgetsOnAllPlatforms("inserts new item on ENTER at end of existing item", (tester) async {
         final context = await tester //
             .createDocument()

super_editor/test/super_editor/components/paragraph_test.dart

@@ -3,13 +3,10 @@ import 'package:flutter/services.dart';
 import 'package:flutter_test/flutter_test.dart';
 import 'package:flutter_test_robots/flutter_test_robots.dart';
 import 'package:flutter_test_runners/flutter_test_runners.dart';
-import 'package:super_editor/src/core/editor.dart';
-import 'package:super_editor/src/default_editor/attributions.dart';
-import 'package:super_editor/src/default_editor/paragraph.dart';
-import 'package:super_editor/src/default_editor/text.dart';
 import 'package:super_editor/super_editor.dart';
 import 'package:super_editor/super_editor_test.dart';
 
+import '../../test_runners.dart';
 import '../supereditor_test_tools.dart';
 
 void main() {
@@ -391,10 +388,11 @@ void main() {
         expect(newParagraph.indent, 0);
       });
 
-      testWidgetsOnDesktop("Backspace at start of text un-indents paragraph", (tester) async {
+      testWidgetsOnDesktopAndWeb("Backspace at start of text un-indents paragraph", (tester) async {
         await tester //
             .createDocument()
             .withSingleParagraph()
+            .withInputSource(TextInputSource.ime)
             .pump();
 
         await tester.placeCaretInParagraph("1", 0);