feat!: announce toasts via shared ARIA live region (#9672)

* feat: announce toasts via shared ARIA live region

* chore: add extra space

Author: mikeharv

packages/blockly/core/toast.ts

@@ -45,7 +45,7 @@ export interface ToastOptions {
    * How prominently/interrupting the readout of the toast should be for
    * screenreaders. Corresponds to aria-live and defaults to polite.
    */
-  assertiveness?: Toast.Assertiveness;
+  assertiveness?: aria.LiveRegionAssertiveness;
 }
 
 /**
@@ -89,15 +89,13 @@ export class Toast {
     const {
       message,
       duration = 5,
-      assertiveness = Toast.Assertiveness.POLITE,
+      assertiveness = aria.LiveRegionAssertiveness.POLITE,
     } = options;
 
     const toast = document.createElement('div');
     workspace.getInjectionDiv().appendChild(toast);
     toast.dataset.toastId = options.id;
     toast.className = CLASS_NAME;
-    aria.setRole(toast, aria.Role.STATUS);
-    aria.setState(toast, aria.State.LIVE, assertiveness);
 
     const messageElement = toast.appendChild(document.createElement('div'));
     messageElement.className = MESSAGE_CLASS_NAME;
@@ -157,6 +155,11 @@ export class Toast {
     toast.addEventListener('mouseleave', setToastTimeout);
     setToastTimeout();
 
+    aria.announceDynamicAriaState(message, {
+      assertiveness,
+      role: aria.Role.STATUS,
+    });
+
     return toast;
   }
 
@@ -174,17 +177,6 @@ export class Toast {
   }
 }
 
-/**
- * Options for how aggressively toasts should be read out by screenreaders.
- * Values correspond to those for aria-live.
- */
-export namespace Toast {
-  export enum Assertiveness {
-    ASSERTIVE = 'assertive',
-    POLITE = 'polite',
-  }
-}
-
 Css.register(`
 .${CLASS_NAME} {
   font-size: 1.2rem;

packages/blockly/tests/mocha/toast_test.js

@@ -14,6 +14,7 @@ suite('Toasts', function () {
   setup(function () {
     sharedTestSetup.call(this);
     this.workspace = Blockly.inject('blocklyDiv', {});
+    this.liveRegion = document.getElementById('blocklyAriaAnnounce');
     this.toastIsVisible = (message) => {
       const toast = this.workspace
         .getInjectionDiv()
@@ -97,16 +98,20 @@ suite('Toasts', function () {
     clock.restore();
   });
 
-  test('default to polite assertiveness', function () {
+  test('toast announces message with status role and polite assertiveness', function () {
     const message = 'texas toast';
     Blockly.Toast.show(this.workspace, {message, id: 'test'});
-    const toast = this.workspace
-      .getInjectionDiv()
-      .querySelector('.blocklyToast');
 
+    this.clock.tick(11);
+
+    assert.include(this.liveRegion.textContent, message);
     assert.equal(
-      toast.getAttribute('aria-live'),
-      Blockly.Toast.Assertiveness.POLITE,
+      this.liveRegion.getAttribute('role'),
+      Blockly.utils.aria.Role.STATUS,
+    );
+    assert.equal(
+      this.liveRegion.getAttribute('aria-live'),
+      Blockly.utils.aria.LiveRegionAssertiveness.POLITE,
     );
   });
 
@@ -115,15 +120,26 @@ suite('Toasts', function () {
     Blockly.Toast.show(this.workspace, {
       message,
       id: 'test',
-      assertiveness: Blockly.Toast.Assertiveness.ASSERTIVE,
+      assertiveness: Blockly.utils.aria.LiveRegionAssertiveness.ASSERTIVE,
     });
+
+    this.clock.tick(11);
+
+    assert.equal(
+      this.liveRegion.getAttribute('aria-live'),
+      Blockly.utils.aria.LiveRegionAssertiveness.ASSERTIVE,
+    );
+  });
+
+  test('toast is not itself a live region', function () {
+    const message = 'texas toast';
+    Blockly.Toast.show(this.workspace, {message, id: 'test'});
+
     const toast = this.workspace
       .getInjectionDiv()
       .querySelector('.blocklyToast');
 
-    assert.equal(
-      toast.getAttribute('aria-live'),
-      Blockly.Toast.Assertiveness.ASSERTIVE,
-    );
+    assert.isNull(toast.getAttribute('aria-live'));
+    assert.notEqual(toast.getAttribute('role'), Blockly.utils.aria.Role.STATUS);
   });
 });