add some tests

packages/button/src/vaadin-button-base.js

@@ -19,8 +19,8 @@ export const buttonStyles = css`
     display: none !important;
   }
 
-  :host([disabled][tabindex='-1']) {
-    pointer-events: none;
+  :host([disabled]) {
+    pointer-events: var(--_vaadin-button-disabled-pointer-events, none);
   }
 
   /* Aligns the button with form fields when placed on the same line.

packages/button/src/vaadin-button-mixin.js

@@ -64,6 +64,10 @@ export const ButtonMixin = (superClass) =>
       if (!this.hasAttribute('role')) {
         this.setAttribute('role', 'button');
       }
+
+      if (this._shouldAllowFocusWhenDisabled()) {
+        this.style.setProperty('--_vaadin-button-disabled-pointer-events', 'auto');
+      }
     }
 
     /**

packages/menu-bar/test/focusable-disabled-buttons-lit.test.js

@@ -0,0 +1,3 @@
+import './not-animated-styles.js';
+import '../theme/lumo/vaadin-lit-menu-bar.js';
+import './menu-bar.common.js';

packages/menu-bar/test/focusable-disabled-buttons-polymer.test.js

@@ -0,0 +1,3 @@
+import './not-animated-styles.js';
+import '../vaadin-menu-bar.js';
+import './focusable-disabled-buttons.common.js';

packages/menu-bar/test/focusable-disabled-buttons.common.js

@@ -0,0 +1,84 @@
+import { expect } from '@vaadin/chai-plugins';
+import { fixtureSync, middleOfNode, nextRender } from '@vaadin/testing-helpers';
+import { resetMouse, sendKeys, sendMouse } from '@web/test-runner-commands';
+
+describe('focusable disabled buttons', () => {
+  let menuBar, buttons;
+
+  before(() => {
+    window.Vaadin.featureFlags ??= {};
+    window.Vaadin.featureFlags.focusableDisabledComponents = true;
+  });
+
+  after(() => {
+    window.Vaadin.featureFlags.focusableDisabledComponents = false;
+  });
+
+  beforeEach(async () => {
+    menuBar = fixtureSync('<vaadin-menu-bar></vaadin-menu-bar>');
+    menuBar.items = [
+      { text: 'Item 0' },
+      { text: 'Item 1', disabled: true, children: [{ text: 'SubItem 0' }] },
+      { text: 'Item 2' },
+    ];
+    await nextRender(menuBar);
+    buttons = menuBar._buttons;
+  });
+
+  afterEach(async () => {
+    await resetMouse();
+  });
+
+  it('should not open sub-menu on disabled button click', async () => {
+    const { x, y } = middleOfNode(buttons[1]);
+    await sendMouse({ type: 'click', position: [Math.floor(x), Math.floor(y)] });
+    expect(buttons[1].hasAttribute('expanded')).to.be.false;
+  });
+
+  it('should not open sub-menu on disabled button hover', async () => {
+    menuBar.openOnHover = true;
+    const { x, y } = middleOfNode(buttons[1]);
+    await sendMouse({ type: 'move', position: [Math.floor(x), Math.floor(y)] });
+    expect(buttons[1].hasAttribute('expanded')).to.be.false;
+  });
+
+  it('should include disabled buttons in arrow key navigation', async () => {
+    await sendKeys({ press: 'Tab' });
+    expect(document.activeElement).to.equal(buttons[0]);
+
+    await sendKeys({ press: 'ArrowRight' });
+    expect(document.activeElement).to.equal(buttons[1]);
+
+    await sendKeys({ press: 'ArrowRight' });
+    expect(document.activeElement).to.equal(buttons[2]);
+
+    await sendKeys({ press: 'ArrowLeft' });
+    expect(document.activeElement).to.equal(buttons[1]);
+
+    await sendKeys({ press: 'ArrowLeft' });
+    expect(document.activeElement).to.equal(buttons[0]);
+  });
+
+  it('should include disabled buttons in Tab navigation', async () => {
+    menuBar.tabNavigation = true;
+
+    await sendKeys({ press: 'Tab' });
+    expect(document.activeElement).to.equal(buttons[0]);
+
+    await sendKeys({ press: 'Tab' });
+    expect(document.activeElement).to.equal(buttons[1]);
+
+    await sendKeys({ press: 'Tab' });
+    expect(document.activeElement).to.equal(buttons[2]);
+
+    await sendKeys({ down: 'Shift' });
+    await sendKeys({ press: 'Tab' });
+    await sendKeys({ up: 'Shift' });
+    expect(document.activeElement).to.equal(buttons[1]);
+
+    await sendKeys({ down: 'Shift' });
+    await sendKeys({ press: 'Tab' });
+    await sendKeys({ up: 'Shift' });
+    expect(document.activeElement).to.equal(buttons[0]);
+  });
+});