[EuiCodeBlock] Improve accessibility of expandable code blocks (elast…

…ic#8195)

packages/eui/changelogs/upcoming/8195.md

@@ -0,0 +1,7 @@
+**Accessibility**
+
+- Improved the accessibility of `EuiCodeBlock`s by
+  - adding screen reader only labels
+  - adding `role="dialog"` on in fullscreen mode
+  - ensuring focus is returned on closing fullscreen mode
+

packages/eui/src/components/code/__snapshots__/code_block.test.tsx.snap

@@ -63,6 +63,25 @@ exports[`EuiCodeBlock renders a code block 1`] = `
     class="euiCodeBlock__pre emotion-euiCodeBlock__pre-preWrap-padding"
     tabindex="-1"
   >
+    <span
+      aria-hidden="true"
+      class="euiScreenReaderOnly"
+      data-tabular-copy-marker="no-copy"
+    >
+      ✄𐘗
+    </span>
+    <div
+      class="emotion-euiScreenReaderOnly"
+    >
+      text code block:
+    </div>
+    <span
+      aria-hidden="true"
+      class="euiScreenReaderOnly"
+      data-tabular-copy-marker="no-copy"
+    >
+      ✄𐘗
+    </span>
     <code
       aria-label="aria-label"
       class="euiCodeBlock__code emotion-euiCodeBlock__code"

packages/eui/src/components/code/code_block.test.tsx

@@ -7,7 +7,8 @@
  */
 
 import React from 'react';
-import { fireEvent } from '@testing-library/react';
+import { fireEvent, waitFor } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
 
 import { requiredProps } from '../../test/required_props';
 import { render } from '../../test/rtl';
@@ -147,7 +148,63 @@ describe('EuiCodeBlock', () => {
       ).toBeInTheDocument();
     });
 
-    it('closes fullscreen mode when the Escape key is pressed', () => {
+    describe('keyboard navigation', () => {
+      it('correctly navigates fullscreen with keyboard', () => {
+        const { getByLabelText, baseElement } = render(
+          <EuiCodeBlock
+            {...requiredProps}
+            language="javascript"
+            overflowHeight={300}
+          >
+            const value = &quot;hello&quot;
+          </EuiCodeBlock>
+        );
+
+        (baseElement.querySelector(
+          '.euiCodeBlock__pre'
+        ) as HTMLPreElement)!.focus(); // start on focusable code block element
+
+        expect(getByLabelText('Expand')).toBeInTheDocument();
+
+        userEvent.keyboard('{tab}');
+
+        waitFor(() => expect(getByLabelText('Expand')).toHaveFocus());
+
+        userEvent.keyboard('{enter}');
+
+        waitFor(() =>
+          expect(
+            baseElement.querySelector('.euiCodeBlockFullScreen')
+          ).toBeInTheDocument()
+        );
+
+        userEvent.keyboard('{tab}');
+
+        waitFor(() =>
+          expect(
+            baseElement.querySelector(
+              '.euiCodeBlockFullScreen .euiCodeBlock__pre'
+            )
+          ).toHaveFocus()
+        );
+
+        userEvent.keyboard('{tab}');
+
+        waitFor(() => expect(getByLabelText('Collapse')).toHaveFocus());
+
+        userEvent.keyboard('{enter}');
+
+        waitFor(() => {
+          expect(
+            baseElement.querySelector('.euiCodeBlockFullScreen')
+          ).not.toBeInTheDocument();
+
+          expect(getByLabelText('Expand')).toHaveFocus();
+        });
+      });
+    });
+
+    it('closes fullscreen mode when the escape key is pressed', () => {
       const { getByLabelText, baseElement } = render(
         <EuiCodeBlock
           {...requiredProps}
@@ -169,6 +226,8 @@ describe('EuiCodeBlock', () => {
       expect(
         baseElement.querySelector('.euiCodeBlockFullScreen')
       ).not.toBeInTheDocument();
+
+      waitFor(() => expect(getByLabelText('Expand')).toHaveFocus());
     });
   });
 

packages/eui/src/components/code/code_block.tsx

@@ -14,6 +14,7 @@ import {
   useCombinedRefs,
   useEuiTheme,
   useEuiMemoizedStyles,
+  tabularCopyMarkers,
 } from '../../services';
 import { ExclusiveUnion } from '../common';
 import {
@@ -37,6 +38,8 @@ import {
   euiCodeBlockPreStyles,
   euiCodeBlockCodeStyles,
 } from './code_block.styles';
+import { EuiScreenReaderOnly } from '../accessibility';
+import { useEuiI18n } from '../i18n';
 
 // Based on observed line height for non-virtualized code blocks
 const fontSizeToRowHeightMap = {
@@ -235,7 +238,6 @@ export const EuiCodeBlock: FunctionComponent<EuiCodeBlockProps> = ({
             : preStyles.whiteSpace.preWrap.controlsOffset.xl),
       ],
       tabIndex: 0,
-      onKeyDown,
     };
 
     return [preProps, preFullscreenProps];
@@ -245,7 +247,6 @@ export const EuiCodeBlock: FunctionComponent<EuiCodeBlockProps> = ({
     isVirtualized,
     hasControls,
     paddingSize,
-    onKeyDown,
     tabIndex,
   ]);
 
@@ -264,6 +265,25 @@ export const EuiCodeBlock: FunctionComponent<EuiCodeBlockProps> = ({
     };
   }, [codeStyles, language, isVirtualized, rest]);
 
+  const codeBlockLabel = useEuiI18n(
+    'euiCodeBlock.label',
+    '{language} code block:',
+    {
+      language,
+    }
+  );
+  // pre tags don't accept aria-label without an
+  // appropriate role, we add a SR only text instead
+  const codeBlockLabelElement = (
+    <>
+      {tabularCopyMarkers.hiddenNoCopyBoundary}
+      <EuiScreenReaderOnly>
+        <div>{codeBlockLabel}</div>
+      </EuiScreenReaderOnly>
+      {tabularCopyMarkers.hiddenNoCopyBoundary}
+    </>
+  );
+
   return (
     <div
       css={cssStyles}
@@ -280,6 +300,7 @@ export const EuiCodeBlock: FunctionComponent<EuiCodeBlockProps> = ({
         />
       ) : (
         <pre {...preProps} ref={combinedRef} style={overflowHeightStyles}>
+          {codeBlockLabelElement}
           <code {...codeProps}>{content}</code>
         </pre>
       )}
@@ -289,7 +310,7 @@ export const EuiCodeBlock: FunctionComponent<EuiCodeBlockProps> = ({
       />
 
       {isFullScreen && (
-        <EuiCodeBlockFullScreenWrapper>
+        <EuiCodeBlockFullScreenWrapper onClose={onKeyDown}>
           {isVirtualized ? (
             <EuiCodeBlockVirtualized
               data={data}
@@ -299,6 +320,7 @@ export const EuiCodeBlock: FunctionComponent<EuiCodeBlockProps> = ({
             />
           ) : (
             <pre {...preFullscreenProps}>
+              {codeBlockLabelElement}
               <code {...codeProps}>{content}</code>
             </pre>
           )}

packages/eui/src/components/code/code_block_copy.tsx

@@ -7,6 +7,8 @@
  */
 
 import React, { ReactNode, useMemo } from 'react';
+
+import { noCopyBoundsRegex } from '../../services';
 import { useInnerText } from '../inner_text';
 import { EuiCopy } from '../copy';
 import { useEuiI18n } from '../i18n';
@@ -28,17 +30,23 @@ export const useCopy = ({
   children: ReactNode;
 }) => {
   const [innerTextRef, _innerText] = useInnerText('');
-  const innerText = useMemo(
-    () =>
+  const innerText = useMemo(() => {
+    if (!_innerText) return;
+
+    return (
       _innerText
+        // remove text that should not be copied (e.g. screen reader instructions)
+        ?.replace(noCopyBoundsRegex, '')
         // Normalize line terminations to match native JS format
         ?.replace(NEW_LINE_REGEX_GLOBAL, '\n')
+        // remove initial line break (if there was hidden content removed)
+        ?.replace(/^\n/, '')
         // Reduce two or more consecutive new line characters to a single one
         // This is needed primarily because of how syntax highlighting
         // generated DOM elements affect `innerText` output.
-        .replace(/\n{2,}/g, '\n') || '',
-    [_innerText]
-  );
+        ?.replace(/\n{2,}/g, '\n') || ''
+    );
+  }, [_innerText]);
   const textToCopy = isVirtualized ? `${children}` : innerText; // Virtualized code blocks do not have inner text
 
   const showCopyButton = isCopyable && textToCopy;

packages/eui/src/components/code/code_block_full_screen.tsx

@@ -13,13 +13,15 @@ import React, {
   useCallback,
   useMemo,
   PropsWithChildren,
+  useRef,
 } from 'react';
 import { keys, useEuiMemoizedStyles } from '../../services';
 import { useEuiI18n } from '../i18n';
 import { EuiButtonIcon } from '../button';
 import { EuiFocusTrap } from '../focus_trap';
 import { EuiOverlayMask } from '../overlay_mask';
 import { euiCodeBlockStyles } from './code_block.styles';
+import { EuiDelayRender } from '../delay_render';
 
 /**
  * Hook that returns fullscreen-related state/logic/utils
@@ -29,13 +31,26 @@ export const useFullScreen = ({
 }: {
   overflowHeight?: number | string;
 }) => {
+  const toggleButtonRef = useRef<HTMLButtonElement>(null);
+
   const showFullScreenButton = !!overflowHeight;
 
   const [isFullScreen, setIsFullScreen] = useState(false);
 
+  const returnFocus = () => {
+    // uses timeout to ensure focus is placed after potential other updates happen
+    setTimeout(() => {
+      toggleButtonRef.current?.focus();
+    });
+  };
+
   const toggleFullScreen = useCallback(() => {
     setIsFullScreen((isFullScreen) => !isFullScreen);
-  }, []);
+
+    if (isFullScreen) {
+      returnFocus();
+    }
+  }, [isFullScreen]);
 
   const onKeyDown = useCallback((event: KeyboardEvent<HTMLElement>) => {
     if (event.key === keys.ESCAPE) {
@@ -48,6 +63,8 @@ export const useFullScreen = ({
         event.preventDefault();
         event.stopPropagation();
         setIsFullScreen(false);
+
+        returnFocus();
       }
     }
   }, []);
@@ -61,14 +78,25 @@ export const useFullScreen = ({
   );
 
   const fullScreenButton = useMemo(() => {
-    return showFullScreenButton ? (
+    const button = (
       <EuiButtonIcon
+        buttonRef={toggleButtonRef}
         className="euiCodeBlock__fullScreenButton"
         onClick={toggleFullScreen}
         iconType={isFullScreen ? 'fullScreenExit' : 'fullScreen'}
         color="text"
         aria-label={isFullScreen ? fullscreenCollapse : fullscreenExpand}
       />
+    );
+
+    return showFullScreenButton ? (
+      isFullScreen ? (
+        // use delay to prevent label being updated in non-fullscreen state before fullscreen is opened
+        // otherwise this causes screen readers to read the collapse label before anything else (as the button was focused when opening)
+        <EuiDelayRender delay={10}>{button}</EuiDelayRender>
+      ) : (
+        button
+      )
     ) : null;
   }, [
     showFullScreenButton,
@@ -89,19 +117,37 @@ export const useFullScreen = ({
  * Portalled full screen wrapper
  */
 export const EuiCodeBlockFullScreenWrapper: FunctionComponent<
-  PropsWithChildren
-> = ({ children }) => {
+  PropsWithChildren & {
+    onClose: (event: React.KeyboardEvent<HTMLElement>) => void;
+  }
+> = ({ children, onClose }) => {
   const styles = useEuiMemoizedStyles(euiCodeBlockStyles);
   const cssStyles = [
     styles.euiCodeBlock,
     styles.l, // Force fullscreen to use large font
     styles.isFullScreen,
   ];
 
+  const ariaLabel = useEuiI18n(
+    'euiCodeBlockFullScreen.ariaLabel',
+    'Expanded code block'
+  );
+
+  const dialogProps = {
+    role: 'dialog',
+    'aria-modal': true,
+    'aria-label': ariaLabel,
+    onKeyDown: onClose,
+  };
+
   return (
     <EuiOverlayMask>
       <EuiFocusTrap scrollLock preventScrollOnFocus clickOutsideDisables={true}>
-        <div className="euiCodeBlockFullScreen" css={cssStyles}>
+        <div
+          className="euiCodeBlockFullScreen"
+          css={cssStyles}
+          {...dialogProps}
+        >
           {children}
         </div>
       </EuiFocusTrap>

packages/eui/src/services/copy/index.ts

@@ -9,5 +9,6 @@
 export { copyToClipboard } from './copy_to_clipboard';
 export {
   tabularCopyMarkers,
+  noCopyBoundsRegex,
   OverrideCopiedTabularContent,
 } from './tabular_copy';

packages/eui/src/services/copy/tabular_copy.tsx

@@ -22,7 +22,7 @@ export const CHARS = {
   NO_COPY_BOUND: '✄𐘗',
 };
 // This regex finds all content between two bounds
-const noCopyBoundsRegex = new RegExp(
+export const noCopyBoundsRegex = new RegExp(
   `${CHARS.NO_COPY_BOUND}[^${CHARS.NO_COPY_BOUND}]*${CHARS.NO_COPY_BOUND}`,
   'gs'
 );