fix(Loader): Adding labeling when loader get focus (#2352)

* adding labelling when loader get focus

* Update docs/src/examples/components/Loader/BestPractices/LoaderBestPractices.tsx

Co-Authored-By: Juraj Kapsiar <jurokapsiar@gmail.com>

* Update packages/react/src/components/Loader/Loader.tsx

Co-Authored-By: Juraj Kapsiar <jurokapsiar@gmail.com>

* changes after review

* prettier applied

* changelog update

* reducing the code, apply fix from review

* lint fix

* fix unit test

Co-authored-by: Juraj Kapsiar <jurokapsiar@gmail.com>

Author: kolaps33

CHANGELOG.md

@@ -32,6 +32,7 @@ This project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.htm
 - Fix `input` descenders being cropped in the Teams theme @bcalvery ([#2335](https://github.com/microsoft/fluent-ui-react/pull/2335))
 - Use referentially equal objects for `actions` in `useStateManager` @layershifter ([#2347](https://github.com/microsoft/fluent-ui-react/pull/2347))
 - Fix `Animation` component not to throw when `children` is not provided @mnajdova ([#2345](https://github.com/microsoft/fluent-ui-react/pull/2345))
+- Fix `loader` - adding labeling when loader get focus @kolaps33 ([#2352](https://github.com/microsoft/fluent-ui-react/pull/2352))
 
 ### Features
 - Added sourcemaps to the dist output to simplify debugging @miroslavstastny ([#2329](https://github.com/microsoft/fluent-ui-react/pull/2329))

docs/src/examples/components/Loader/BestPractices/LoaderBestPractices.tsx

@@ -0,0 +1,14 @@
+import * as React from 'react'
+
+import ComponentBestPractices from '../../../../components/ComponentBestPractices'
+
+const doList = [
+  'Use react-aria-live or similar component to announce the loading state.',
+  'If loader is only the element in the screen or region, consider making it focusable by setting `tabIndex` prop to the `Loader`. In most of these cases value of `tabIndex` should be 0.',
+]
+
+const LoaderBestPractices: React.FunctionComponent<{}> = () => {
+  return <ComponentBestPractices doList={doList} />
+}
+
+export default LoaderBestPractices

packages/accessibility/src/behaviors/Loader/loaderBehavior.ts

@@ -3,17 +3,37 @@ import { Accessibility } from '../../types'
 /**
  * @description
  * Loader is usually an element that displays the progress status for a task that take a long time or consists of several steps.
+ * Adds attribute 'aria-labelledby' on 'root' when loader has 'tabIndex' prop. This can be overriden by providing 'aria-labelledby' or 'aria-label' property directly to the component.
  *
  * @specification
  * Adds role 'progressbar' to 'root' slot.
  */
 
-const loaderBehavior: Accessibility = () => ({
-  attributes: {
-    root: {
-      role: 'progressbar',
+const loaderBehavior: Accessibility<LoaderBehaviorProps> = props => {
+  return {
+    attributes: {
+      root: {
+        role: 'progressbar',
+        'aria-labelledby': getDefaultAriaLabelledBy(props),
+      },
     },
-  },
-})
+  }
+}
+
+type LoaderBehaviorProps = {
+  /** id of the loader label element. */
+  labelId?: string
+}
 
 export default loaderBehavior
+
+/**
+ * Returns the id of the loader label if user provide tabIndex prop. It is used when user does not provide aria-label or
+ * aria-labelledby as prop.
+ */
+const getDefaultAriaLabelledBy = (props: LoaderBehaviorProps) => {
+  if (props['aria-label'] || props['aria-labelledby']) {
+    return undefined
+  }
+  return props['tabIndex'] === undefined ? undefined : props.labelId
+}

packages/accessibility/test/behaviors/loaderBehavior-test.tsx

@@ -0,0 +1,33 @@
+import { loaderBehavior } from '@fluentui/accessibility'
+
+describe('LoaderBehavior.ts', () => {
+  test('do NOT add aria-labelledby, when aria-label was set already', () => {
+    const props = { labelId: 'label-id', 'aria-label': 'any loading string' }
+    const expectedResult = loaderBehavior(props)
+    expect(expectedResult.attributes.root['aria-labelledby']).toEqual(undefined)
+  })
+
+  test('do NOT add aria-labelledby, when aria-labelled was set already', () => {
+    const props = { labelId: 'label-id', 'aria-labelledby': 'id' }
+    const expectedResult = loaderBehavior(props)
+    expect(expectedResult.attributes.root['aria-labelledby']).toEqual(undefined)
+  })
+
+  test('do NOT add aria-labelledby, when there is no tabIndex specified', () => {
+    const props = { labelId: 'label-id' }
+    const expectedResult = loaderBehavior(props)
+    expect(expectedResult.attributes.root['aria-labelledby']).toEqual(undefined)
+  })
+
+  test('add aria-labelledby, when there is tabIndex=0 specified', () => {
+    const props = { labelId: 'label-id', tabIndex: 0 }
+    const expectedResult = loaderBehavior(props)
+    expect(expectedResult.attributes.root['aria-labelledby']).toEqual('label-id')
+  })
+
+  test('add aria-labelledby, when there is tabIndex=-1 specified', () => {
+    const props = { labelId: 'label-id', tabIndex: -1 }
+    const expectedResult = loaderBehavior(props)
+    expect(expectedResult.attributes.root['aria-labelledby']).toEqual('label-id')
+  })
+})

packages/react/src/components/Loader/Loader.tsx

@@ -10,6 +10,7 @@ import {
   commonPropTypes,
   SizeValue,
   ShorthandFactory,
+  getOrGenerateIdFromShorthand,
 } from '../../utils'
 import { WithAsProp, ShorthandValue, withSafeTypeForAs } from '../../types'
 import Box, { BoxProps } from '../Box/Box'
@@ -49,6 +50,7 @@ export interface LoaderProps extends UIComponentProps {
 
 export interface LoaderState {
   visible: boolean
+  labelId: string
 }
 
 /**
@@ -94,6 +96,13 @@ class Loader extends UIComponent<WithAsProp<LoaderProps>, LoaderState> {
 
     this.state = {
       visible: this.props.delay === 0,
+      labelId: '',
+    }
+  }
+
+  static getDerivedStateFromProps(props, state) {
+    return {
+      labelId: getOrGenerateIdFromShorthand('loader-label-', props.label, state.labelId),
     }
   }
 
@@ -114,7 +123,7 @@ class Loader extends UIComponent<WithAsProp<LoaderProps>, LoaderState> {
 
   renderComponent({ ElementType, classes, accessibility, variables, styles, unhandledProps }) {
     const { indicator, label, svg } = this.props
-    const { visible } = this.state
+    const { visible, labelId } = this.state
 
     const svgElement = Box.create(svg, {
       defaultProps: () => ({ className: Loader.slotClassNames.svg, styles: styles.svg }),
@@ -135,7 +144,11 @@ class Loader extends UIComponent<WithAsProp<LoaderProps>, LoaderState> {
             }),
           })}
           {Text.create(label, {
-            defaultProps: () => ({ className: Loader.slotClassNames.label, styles: styles.label }),
+            defaultProps: () => ({
+              className: Loader.slotClassNames.label,
+              styles: styles.label,
+              id: labelId,
+            }),
           })}
         </ElementType>
       )