fix: Make live region coalesce messages

packages/blockly/core/utils/aria.ts

@@ -33,6 +33,9 @@ export enum LiveRegionAssertiveness {
   POLITE = 'polite',
 }
 
+let nextAnnouncementAssertiveness = LiveRegionAssertiveness.OFF;
+const queuedAnnouncements: string[] = [];
+
 /**
  * Customization options that can be passed when using `announceDynamicAriaState`.
  */
@@ -379,21 +382,51 @@ export function announceDynamicAriaState(
     role = DEFAULT_LIVE_REGION_ROLE,
   } = options || {};
 
+  queuedAnnouncements.push(text);
+  nextAnnouncementAssertiveness = mostAssertive(
+    assertiveness,
+    nextAnnouncementAssertiveness,
+  );
+
   // We use a short delay so rapid successive calls collapse into a single
   // announcement, and to ensure assistive technologies reliably detect the
   // DOM change.
   clearTimeout(ariaAnnounceTimeout);
   ariaAnnounceTimeout = setTimeout(() => {
     // Clear previous content.
     ariaAnnouncementContainer.replaceChildren();
-    setState(ariaAnnouncementContainer, State.LIVE, assertiveness);
+    setState(
+      ariaAnnouncementContainer,
+      State.LIVE,
+      nextAnnouncementAssertiveness,
+    );
     setRole(ariaAnnouncementContainer, role);
 
     const span = document.createElement('span');
     // The non-breaking space toggle ensures otherwise identical consecutive
     // messages are still announced.
-    span.textContent = text + (addBreakingSpace ? '\u00A0' : '');
+    span.textContent =
+      queuedAnnouncements.join('\n') + (addBreakingSpace ? '\u00A0' : '');
     addBreakingSpace = !addBreakingSpace;
     ariaAnnouncementContainer.appendChild(span);
+    queuedAnnouncements.length = 0;
+    nextAnnouncementAssertiveness = LiveRegionAssertiveness.OFF;
   }, 10);
 }
+
+/** Returns the maximally assertive of the given assertiveness levels. */
+function mostAssertive(a: LiveRegionAssertiveness, b: LiveRegionAssertiveness) {
+  if (
+    a === LiveRegionAssertiveness.ASSERTIVE ||
+    b === LiveRegionAssertiveness.ASSERTIVE
+  ) {
+    return LiveRegionAssertiveness.ASSERTIVE;
+  } else if (
+    a === LiveRegionAssertiveness.POLITE ||
+    b === LiveRegionAssertiveness.POLITE
+  ) {
+    return LiveRegionAssertiveness.POLITE;
+  }
+
+  return LiveRegionAssertiveness.OFF;
+}

packages/blockly/tests/mocha/aria_test.js

@@ -103,14 +103,33 @@ suite('ARIA', function () {
       assert.notEqual(first, second);
     });
 
-    test('last write wins when called rapidly', function () {
+    test('Coalesces messages when called rapidly', function () {
       Blockly.utils.aria.announceDynamicAriaState('First message');
       Blockly.utils.aria.announceDynamicAriaState('Second message');
       Blockly.utils.aria.announceDynamicAriaState('Final message');
 
       this.clock.tick(11);
 
-      assert.include(this.liveRegion.textContent, 'Final message');
+      assert.include(
+        this.liveRegion.textContent,
+        'First message\nSecond message\nFinal message',
+      );
+    });
+
+    test('Uses maximal assertiveness when coalescing', function () {
+      Blockly.utils.aria.announceDynamicAriaState('First message', {
+        assertiveness: Blockly.utils.aria.LiveRegionAssertiveness.OFF,
+      });
+      Blockly.utils.aria.announceDynamicAriaState('Second message', {
+        assertiveness: Blockly.utils.aria.LiveRegionAssertiveness.ASSERTIVE,
+      });
+      Blockly.utils.aria.announceDynamicAriaState('Final message', {
+        assertiveness: Blockly.utils.aria.LiveRegionAssertiveness.POLITE,
+      });
+
+      this.clock.tick(11);
+
+      assert.equal(this.liveRegion.getAttribute('aria-live'), 'assertive');
     });
 
     test('assertive option sets aria-live assertive', function () {

packages/blockly/tests/mocha/keyboard_movement_test.js

@@ -1040,7 +1040,7 @@ suite('Keyboard-driven movement', function () {
 
         Blockly.getFocusManager().focusNode(valueBlock);
         startMove(this.workspace);
-
+        this.clock.tick(10);
         this.moveAndAssert(
           moveRight,
           ['moving', 'inside', this.getBlockLabel(parent)],
@@ -1057,6 +1057,7 @@ suite('Keyboard-driven movement', function () {
         Blockly.getFocusManager().focusNode(loop);
         startMove(this.workspace);
         moveRight(this.workspace);
+        this.clock.tick(10);
 
         this.moveAndAssert(
           moveRight,
@@ -1081,6 +1082,7 @@ suite('Keyboard-driven movement', function () {
         Blockly.getFocusManager().focusNode(ifBlock);
         startMove(this.workspace); // on workspace
         moveRight(this.workspace); // before block1
+        this.clock.tick(10);
         this.moveAndAssert(
           moveRight,
           [
@@ -1114,7 +1116,7 @@ suite('Keyboard-driven movement', function () {
 
         Blockly.getFocusManager().focusNode(boolean);
         startMove(this.workspace);
-
+        this.clock.tick(10);
         this.moveAndAssert(
           moveRight,
           [
@@ -1151,7 +1153,7 @@ suite('Keyboard-driven movement', function () {
         Blockly.getFocusManager().focusNode(text);
         startMove(this.workspace);
         moveRight(this.workspace); // First labeled input
-
+        this.clock.tick(10);
         this.moveAndAssert(
           moveRight,
           ['moving', 'inside', this.getBlockLabel(textJoin), 'input 2'],