add role-helpers function to retrieve superclass from role (testing-library#448)

Author: Bianca Del Carretto

src/__tests__/role-helpers.js

@@ -3,6 +3,7 @@ import {
   logRoles,
   getImplicitAriaRoles,
   isInaccessible,
+  getRolesAndSuperClassByRoles,
 } from '../role-helpers'
 import {render} from './helpers/test-utils'
 
@@ -181,6 +182,48 @@ test.each([
 ])('shouldExcludeFromA11yTree for %s returns %p', (html, expected) => {
   const {container} = render(html)
   container.firstChild.appendChild(document.createElement('button'))
-
   expect(isInaccessible(container.querySelector('button'))).toBe(expected)
 })
+
+test.each([
+  ['', []],
+  ['roletype', ['roletype']],
+  ['switch', ['roletype', 'widget', 'input', 'checkbox', 'switch']],
+  ['input', ['roletype', 'widget', 'input']],
+  [
+    'select',
+    [
+      'roletype',
+      'widget',
+      'composite',
+      'structure',
+      'section',
+      'group',
+      'select',
+    ],
+  ],
+  [
+    ['switch', 'input'],
+    ['roletype', 'widget', 'input', 'checkbox', 'switch'],
+  ],
+  [
+    ['switch', 'select'],
+    [
+      'roletype',
+      'widget',
+      'input',
+      'checkbox',
+      'composite',
+      'structure',
+      'section',
+      'group',
+      'switch',
+      'select',
+    ],
+  ],
+])(
+  'getSuperClassByRole returns expected roles as super class for given roles',
+  (roles, expected) => {
+    expect(getRolesAndSuperClassByRoles(roles).sort()).toEqual(expected.sort())
+  },
+)

src/role-helpers.js

@@ -1,4 +1,4 @@
-import {elementRoles} from 'aria-query'
+import {elementRoles, roles as rolesMap} from 'aria-query'
 import {computeAccessibleName} from 'dom-accessibility-api'
 import {prettyDOM} from './pretty-dom'
 
@@ -196,6 +196,28 @@ function computeAriaSelected(element) {
   return undefined
 }
 
+function getRolesAndSuperClassByRoles(roles) {
+  if (!roles || roles.length === 0) {
+    return []
+  }
+  const rolesList = Array.isArray(roles) ? roles : [roles]
+  const superClasses = rolesList.reduce(
+    (acc, role) => {
+      const roleDefinition = rolesMap.get(role)
+      if (!roleDefinition) {
+        return acc
+      }
+      const superClassesFlatten = roleDefinition.superClass.reduce(
+        (superClassesList, superClass) => [...superClassesList, ...superClass],
+        [],
+      )
+      return [...acc, ...superClassesFlatten]
+    },
+    [...rolesList],
+  )
+  return Array.from(new Set(superClasses))
+}
+
 export {
   getRoles,
   logRoles,
@@ -204,4 +226,5 @@ export {
   prettyRoles,
   isInaccessible,
   computeAriaSelected,
+  getRolesAndSuperClassByRoles,
 }