test: add Playwright test for PM tabs keyboard navigation

Author: damevin

tests/package-manager-tabs.spec.ts

@@ -0,0 +1,35 @@
+import { expect, test } from '@nuxt/test-utils/playwright'
+
+test.describe('Package Page', () => {
+  test('/vue → package manager tabs use roving tabindex', async ({ page, goto }) => {
+    await goto('/vue', { waitUntil: 'domcontentloaded' })
+
+    const tablist = page.locator('[role="tablist"]').first()
+    await expect(tablist).toBeVisible()
+
+    const tabs = tablist.locator('[role="tab"]')
+    const tabCount = await tabs.count()
+    expect(tabCount).toBeGreaterThan(1)
+
+    const firstTab = tabs.first()
+    await firstTab.focus()
+    await expect(firstTab).toBeFocused()
+
+    await page.keyboard.press('ArrowRight')
+
+    const secondTab = tabs.nth(1)
+    await expect(secondTab).toBeFocused()
+    await expect(secondTab).toHaveAttribute('aria-selected', 'true')
+    await expect(secondTab).toHaveAttribute('tabindex', '0')
+    await expect(firstTab).toHaveAttribute('tabindex', '-1')
+
+    const tabpanel = page.locator('[role="tabpanel"]').first()
+    const controls = await secondTab.getAttribute('aria-controls')
+    const panelId = await tabpanel.getAttribute('id')
+    expect(controls).toBe(panelId)
+
+    const labelledBy = await tabpanel.getAttribute('aria-labelledby')
+    const tabId = await secondTab.getAttribute('id')
+    expect(labelledBy).toBe(tabId)
+  })
+})