[SharedUX] Replace Sass with Emotion, Round 1 (#199885)

## Summary

Part of https://github.com/elastic/kibana-team/issues/1082

Selects certain Sass files to replace with styles declared with Emotion.
This PR does not include any changes that would be noticeable by
end-users. It changes the internals to use a different technology for
styling components.

~~Some `className` attributes have been kept, because they are
referenced in JS and tests.~~ Update: all classNames that are no longer
needed for styling purposes have been removed.
* If the className was needed for tests, it has been replaced with a
test-subj.
* If the className was used as a selector in production code, it has
been replaced with alternative JS.

## References
1. https://emotion.sh/docs/globals
2. https://emotion.sh/docs/best-practices
3.
https://github.com/elastic/eui/discussions/6828#discussioncomment-10825360

---------

Co-authored-by: Jatin Kathuria <jatin.kathuria@elastic.co>

packages/core/chrome/core-chrome-browser-internal/src/ui/__snapshots__/loading_indicator.test.tsx.snap

@@ -1,31 +1,62 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
 exports[`kbnLoadingIndicator is hidden by default 1`] = `
-<EuiIcon
+<Fragment>
-  aria-label="Elastic Logo"
+  <EmotionGlobal
-  className="chrHeaderLogo__cluster"
+    styles={
-  data-test-subj="globalLoadingIndicator-hidden"
+      Object {
-  size="l"
+        ".euiHeaderSectionItem .euiButtonEmpty__text": Object {
-  type="logoElastic"
+          "display": "flex",
-/>
+        },
+      }
+    }
+  />
+  <EuiIcon
+    aria-label="Elastic Logo"
+    data-test-subj="globalLoadingIndicator-hidden"
+    size="l"
+    type="logoElastic"
+  />
+</Fragment>
 `;
 
 exports[`kbnLoadingIndicator is visible when loadingCount is > 0 1`] = `
-<EuiIcon
+<Fragment>
-  aria-label="Elastic Logo"
+  <EmotionGlobal
-  className="chrHeaderLogo__cluster"
+    styles={
-  data-test-subj="globalLoadingIndicator-hidden"
+      Object {
-  size="l"
+        ".euiHeaderSectionItem .euiButtonEmpty__text": Object {
-  type="logoElastic"
+          "display": "flex",
-/>
+        },
+      }
+    }
+  />
+  <EuiIcon
+    aria-label="Elastic Logo"
+    data-test-subj="globalLoadingIndicator-hidden"
+    size="l"
+    type="logoElastic"
+  />
+</Fragment>
 `;
 
 exports[`kbnLoadingIndicator shows logo image when customLogo is set 1`] = `
-<EuiImage
+<Fragment>
-  alt="logo"
+  <EmotionGlobal
-  aria-label="User logo"
+    styles={
-  data-test-subj="globalLoadingIndicator-hidden"
+      Object {
-  size={24}
+        ".euiHeaderSectionItem .euiButtonEmpty__text": Object {
-  src="customLogo"
+          "display": "flex",
-/>
+        },
+      }
+    }
+  />
+  <EuiImage
+    alt="logo"
+    aria-label="User logo"
+    data-test-subj="globalLoadingIndicator-hidden"
+    size={24}
+    src="customLogo"
+  />
+</Fragment>
 `;

packages/core/chrome/core-chrome-browser-internal/src/ui/header/__snapshots__/collapsible_nav.test.tsx.snap

@@ -168,7 +168,7 @@ Array [
           >
             <ul
               aria-label="Recently viewed links"
-              class="euiListGroup kbnCollapsibleNav__recentsListGroup emotion-euiListGroup-none"
+              class="euiListGroup emotion-EuiListGroup"
               style="max-inline-size: none;"
             >
               <li
@@ -218,10 +218,10 @@ Array [
       class="euiHorizontalRule emotion-euiHorizontalRule-full"
     />
     <div
-      class="euiFlexItem kbnCollapsibleNav__solutions emotion-euiFlexItem-grow-1"
+      class="euiFlexItem emotion-euiFlexItem-grow-1"
     >
       <div
-        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-euiCollapsibleNavGroup-isCollapsible-none"
+        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-EuiCollapsibleNavGroup"
         data-test-subj="collapsibleNavGroup-kibana"
       >
         <div
@@ -230,7 +230,7 @@ Array [
           <button
             aria-controls="generated-id"
             aria-expanded="true"
-            class="euiAccordion__button kbnCollapsibleNav__solutionGroupButton emotion-euiAccordion__button"
+            class="euiAccordion__button euiCollapsibleNavGroup__heading emotion-euiAccordion__button"
             id="generated-id"
             type="button"
           >
@@ -351,7 +351,7 @@ Array [
         </div>
       </div>
       <div
-        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-euiCollapsibleNavGroup-isCollapsible-none"
+        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-EuiCollapsibleNavGroup"
         data-test-subj="collapsibleNavGroup-observability"
       >
         <div
@@ -360,7 +360,7 @@ Array [
           <button
             aria-controls="generated-id"
             aria-expanded="true"
-            class="euiAccordion__button kbnCollapsibleNav__solutionGroupButton emotion-euiAccordion__button"
+            class="euiAccordion__button euiCollapsibleNavGroup__heading emotion-euiAccordion__button"
             id="generated-id"
             type="button"
           >
@@ -464,7 +464,7 @@ Array [
         </div>
       </div>
       <div
-        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-euiCollapsibleNavGroup-isCollapsible-none"
+        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-EuiCollapsibleNavGroup"
         data-test-subj="collapsibleNavGroup-securitySolution"
       >
         <div
@@ -473,7 +473,7 @@ Array [
           <button
             aria-controls="generated-id"
             aria-expanded="true"
-            class="euiAccordion__button kbnCollapsibleNav__solutionGroupButton emotion-euiAccordion__button"
+            class="euiAccordion__button euiCollapsibleNavGroup__heading emotion-euiAccordion__button"
             id="generated-id"
             type="button"
           >
@@ -560,7 +560,7 @@ Array [
         </div>
       </div>
       <div
-        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-euiCollapsibleNavGroup-isCollapsible-none"
+        class="euiAccordion euiAccordion-isOpen euiCollapsibleNavGroup emotion-euiAccordion-EuiCollapsibleNavGroup"
         data-test-subj="collapsibleNavGroup-management"
       >
         <div
@@ -569,7 +569,7 @@ Array [
           <button
             aria-controls="generated-id"
             aria-expanded="true"
-            class="euiAccordion__button kbnCollapsibleNav__solutionGroupButton emotion-euiAccordion__button"
+            class="euiAccordion__button euiCollapsibleNavGroup__heading emotion-euiAccordion__button"
             id="generated-id"
             type="button"
           >
@@ -858,7 +858,15 @@ exports[`CollapsibleNav renders the default nav 1`] = `
   <EuiCollapsibleNav
     aria-label="Primary"
     button={<button />}
-    className="kbnCollapsibleNav"
+    css={
+      Object {
+        "map": undefined,
+        "name": "1pvcuvk",
+        "next": undefined,
+        "styles": "@media (max-height: 240px){overflow-y:auto;}",
+        "toString": [Function],
+      }
+    }
     data-test-subj="collapsibleNav"
     id="collapsibe-nav"
     isOpen={false}
@@ -1045,7 +1053,15 @@ exports[`CollapsibleNav renders the default nav 2`] = `
   <EuiCollapsibleNav
     aria-label="Primary"
     button={<button />}
-    className="kbnCollapsibleNav"
+    css={
+      Object {
+        "map": undefined,
+        "name": "1pvcuvk",
+        "next": undefined,
+        "styles": "@media (max-height: 240px){overflow-y:auto;}",
+        "toString": [Function],
+      }
+    }
     data-test-subj="collapsibleNav"
     id="collapsibe-nav"
     isOpen={false}

packages/core/chrome/core-chrome-browser-internal/src/ui/header/__snapshots__/header.test.tsx.snap

@@ -56,12 +56,11 @@ Array [
           >
             <a
               aria-label="Elastic home"
-              class="chrHeaderLogo"
+              css="You have tried to stringify object returned from \`css\` function. It isn't supposed to be used directly (e.g. as value of the \`className\` prop), but rather handed to emotion so it can handle it (e.g. as value of \`css\` prop)."
               data-test-subj="logo"
               href="/"
             >
               <span
-                class="chrHeaderLogo__cluster"
                 data-euiicon-type="logoElastic"
                 data-test-subj="globalLoadingIndicator-hidden"
               >
@@ -70,7 +69,8 @@ Array [
               <svg
                 aria-hidden="true"
                 aria-labelledby="elasticMark"
-                class="chrHeaderLogo__mark"
+                css="You have tried to stringify object returned from \`css\` function. It isn't supposed to be used directly (e.g. as value of the \`className\` prop), but rather handed to emotion so it can handle it (e.g. as value of \`css\` prop)."
+                data-test-subj="logoMark"
                 fill="none"
                 height="19"
                 width="64"

packages/core/chrome/core-chrome-browser-internal/src/ui/header/collapsible_nav.scss

@@ -1,46 +0,0 @@
-$screenHeightBreakpoint: $euiSize * 15;
-
-.kbnCollapsibleNav {
-  @media (max-height: $screenHeightBreakpoint) {
-    overflow-y: auto;
-  }
-}
-
-.kbnCollapsibleNav__recentsListGroup {
-  max-height: $euiSize * 10;
-  margin-right: -$euiSizeS;
-  @include euiYScroll;
-}
-
-.kbnCollapsibleNav__solutions {
-  @include euiYScroll;
-
-  /**
-   * Allows the solutions nav group to be viewed on
-   * very small screen sizes and when the browser Zoom is high
-   */
-  @media (max-height: $screenHeightBreakpoint) {
-    flex: 1 0 auto;
-  }
-}
-
-/**
- * 1. Increase the hit area of the link (anchor)
- * 2. Only show the text underline when hovering on the text/anchor portion
- */
-
-.kbnCollapsibleNav__solutionGroupButton {
-  display: block; /* 1 */
-
-  &:hover {
-    text-decoration: none; /* 2 */
-  }
-}
-
-.kbnCollapsibleNav__solutionGroupLink {
-  display: block; /* 1 */
-
-  &:hover {
-    text-decoration: underline; /* 2 */
-  }
-}

packages/core/chrome/core-chrome-browser-internal/src/ui/header/collapsible_nav.tsx

@@ -7,7 +7,6 @@
  * License v3.0 only", or the "Server Side Public License, v 1".
  */
 
-import './collapsible_nav.scss';
 import {
   EuiThemeProvider,
   EuiCollapsibleNav,
@@ -18,6 +17,7 @@ import {
   EuiListGroupItem,
   EuiCollapsibleNavProps,
   EuiButton,
+  useEuiTheme,
 } from '@elastic/eui';
 import { i18n } from '@kbn/i18n';
 import { groupBy, sortBy } from 'lodash';
@@ -36,6 +36,7 @@ import {
   createEuiButtonItem,
   createOverviewLink,
 } from './nav_link';
+import { getCollapsibleNavStyles } from './get_collapsible_nav_styles';
 
 function getAllCategories(allCategorizedLinks: Record<string, ChromeNavLink[]>) {
   const allCategories = {} as Record<string, AppCategory | undefined>;
@@ -149,6 +150,7 @@ export function CollapsibleNav({
       ...(needsIcon && { basePath }),
     });
   };
+  const styles = getCollapsibleNavStyles(useEuiTheme());
 
   return (
     <EuiCollapsibleNav
@@ -162,7 +164,7 @@ export function CollapsibleNav({
       button={button}
       ownFocus={false}
       size={248}
-      className="kbnCollapsibleNav"
+      css={styles.navCss}
     >
       {customNavLink && (
         <>
@@ -275,14 +277,14 @@ export function CollapsibleNav({
             color="subdued"
             gutterSize="none"
             size="s"
-            className="kbnCollapsibleNav__recentsListGroup"
+            css={styles.navRecentsListGroupCss}
           />
         </EuiCollapsibleNavGroup>
       )}
 
       <EuiHorizontalRule margin="none" />
 
-      <EuiFlexItem className="kbnCollapsibleNav__solutions">
+      <EuiFlexItem css={styles.navSolutions}>
         {/* Kibana, Observability, Security, and Management sections */}
         {orderedCategories.map((categoryName) => {
           const category = categoryDictionary[categoryName]!;
@@ -294,11 +296,12 @@ export function CollapsibleNav({
               iconType={category.euiIconType}
               iconSize="m"
               buttonElement={overviewLink ? 'div' : 'button'}
-              buttonClassName="kbnCollapsibleNav__solutionGroupButton"
+              css={styles.navSolutionGroupButton}
               title={
                 overviewLink ? (
                   <a
-                    className="eui-textInheritColor kbnCollapsibleNav__solutionGroupLink"
+                    className="eui-textInheritColor"
+                    css={styles.navSolutionGroupLink}
                     {...createOverviewLink({
                       link: overviewLink,
                       navigateToUrl,

packages/core/chrome/core-chrome-browser-internal/src/ui/header/get_collapsible_nav_styles.ts

@@ -0,0 +1,72 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the "Elastic License
+ * 2.0", the "GNU Affero General Public License v3.0 only", and the "Server Side
+ * Public License v 1"; you may not use this file except in compliance with, at
+ * your election, the "Elastic License 2.0", the "GNU Affero General Public
+ * License v3.0 only", or the "Server Side Public License, v 1".
+ */
+
+import { UseEuiTheme, euiYScroll, mathWithUnits } from '@elastic/eui';
+import { css } from '@emotion/react';
+
+export const getCollapsibleNavStyles = (euiThemeContext: UseEuiTheme) => {
+  const { euiTheme } = euiThemeContext;
+  const screenHeightBreakpoint = mathWithUnits(euiTheme.size.base, (x) => x * 15);
+  const _euiYScroll = euiYScroll(euiThemeContext);
+
+  const navCss = css({
+    [`@media (max-height: ${screenHeightBreakpoint})`]: {
+      overflowY: 'auto',
+    },
+  });
+
+  const navRecentsListGroupCss = [
+    css({
+      maxHeight: `calc(${euiTheme.size.base} * 10)`,
+      marginRight: `-${euiTheme.size.s}`,
+    }),
+    _euiYScroll,
+  ];
+
+  const navSolutions = [
+    _euiYScroll,
+    css({
+      /**
+       * Allows the solutions nav group to be viewed on
+       * very small screen sizes and when the browser Zoom is high
+       */
+      [`@media (max-height: ${screenHeightBreakpoint})`]: {
+        flex: '1 0 auto',
+      },
+    }),
+  ];
+
+  /**
+   * 1. Increase the hit area of the link (anchor)
+   * 2. Only show the text underline when hovering on the text/anchor portion
+   */
+  const navSolutionGroupButton = css({
+    display: 'block' /* 1 */,
+
+    '&:hover': {
+      textDecoration: 'none' /* 2 */,
+    },
+  });
+
+  const navSolutionGroupLink = css({
+    display: 'block' /* 1 */,
+
+    '&:hover': {
+      textDecoration: 'underline' /* 2 */,
+    },
+  });
+
+  return {
+    navCss,
+    navRecentsListGroupCss,
+    navSolutions,
+    navSolutionGroupButton,
+    navSolutionGroupLink,
+  };
+};

packages/core/chrome/core-chrome-browser-internal/src/ui/header/header_logo.scss

@@ -1,11 +0,0 @@
-.chrHeaderLogo {
-  display: flex;
-  align-items: center;
-  height: $euiSizeXXL;
-  padding-inline: $euiSizeS;
-}
-
-.chrHeaderLogo__mark {
-  margin-left: $euiSizeS;
-  fill: $euiColorGhost;
-}

packages/core/chrome/core-chrome-browser-internal/src/ui/header/header_logo.tsx

@@ -7,7 +7,7 @@
  * License v3.0 only", or the "Server Side Public License, v 1".
  */
 
-import './header_logo.scss';
+import { css } from '@emotion/react';
 import { i18n } from '@kbn/i18n';
 import React from 'react';
 import useObservable from 'react-use/lib/useObservable';
@@ -16,6 +16,7 @@ import Url from 'url';
 import { CustomBranding } from '@kbn/core-custom-branding-common';
 import type { HttpStart } from '@kbn/core-http-browser';
 import type { ChromeNavLink } from '@kbn/core-chrome-browser';
+import { useEuiTheme } from '@elastic/eui';
 import { ElasticMark } from './elastic_mark';
 import { LoadingIndicator } from '../loading_indicator';
 
@@ -83,14 +84,29 @@ interface Props {
 }
 
 export function HeaderLogo({ href, navigateToApp, loadingCount$, ...observables }: Props) {
+  const { euiTheme } = useEuiTheme();
   const forceNavigation = useObservable(observables.forceNavigation$, false);
   const navLinks = useObservable(observables.navLinks$, []);
   const customBranding = useObservable(observables.customBranding$, {});
   const { customizedLogo, logo } = customBranding;
+
+  const styles = {
+    logoCss: css({
+      display: 'flex',
+      alignItems: 'center',
+      height: euiTheme.size.xxl,
+      paddingInline: euiTheme.size.s,
+    }),
+    logoMarkCss: css({
+      marginLeft: euiTheme.size.s,
+      fill: euiTheme.colors.ghost,
+    }),
+  };
+
   return (
     <a
       onClick={(e) => onClick(e, forceNavigation, navLinks, navigateToApp)}
-      className="chrHeaderLogo"
+      css={styles.logoCss}
       href={href}
       data-test-subj="logo"
       aria-label={i18n.translate('core.ui.chrome.headerGlobalNav.goHomePageIconAriaLabel', {
@@ -101,12 +117,13 @@ export function HeaderLogo({ href, navigateToApp, loadingCount$, ...observables
       {customizedLogo ? (
         <img
           src={customizedLogo}
-          className="chrHeaderLogo__mark"
+          data-test-subj="logoMark"
+          css={styles.logoMarkCss}
           style={{ maxWidth: '200px', maxHeight: '84px' }}
           alt="custom mark"
         />
       ) : (
-        <ElasticMark className="chrHeaderLogo__mark" aria-hidden={true} />
+        <ElasticMark data-test-subj="logoMark" css={styles.logoMarkCss} aria-hidden={true} />
       )}
     </a>
   );

packages/core/chrome/core-chrome-browser-internal/src/ui/loading_indicator.scss

@@ -1,9 +0,0 @@
-.kbnLoadingIndicator-hidden {
-  visibility: hidden;
-  animation-play-state: paused;
-}
-
-.euiHeaderSectionItem .euiButtonEmpty__text {
-  // stop global header buttons from jumping during loading state
-  display: flex;
-}

packages/core/chrome/core-chrome-browser-internal/src/ui/loading_indicator.test.tsx

@@ -16,7 +16,9 @@ import { LoadingIndicator } from './loading_indicator';
 describe('kbnLoadingIndicator', () => {
   it('is hidden by default', () => {
     const wrapper = shallow(<LoadingIndicator loadingCount$={new BehaviorSubject(0)} />);
-    expect(wrapper.prop('data-test-subj')).toBe('globalLoadingIndicator-hidden');
+    expect(
+      wrapper.findWhere((node) => node.prop('data-test-subj') === 'globalLoadingIndicator-hidden')
+    ).toHaveLength(1);
     expect(wrapper).toMatchSnapshot();
   });
 

packages/core/chrome/core-chrome-browser-internal/src/ui/loading_indicator.tsx

@@ -7,6 +7,7 @@
  * License v3.0 only", or the "Server Side Public License, v 1".
  */
 
+import { Global, css } from '@emotion/react';
 import { EuiLoadingSpinner, EuiProgress, EuiIcon, EuiImage } from '@elastic/eui';
 import { i18n } from '@kbn/i18n';
 import React from 'react';
@@ -14,8 +15,6 @@ import classNames from 'classnames';
 import type { Subscription } from 'rxjs';
 import type { HttpStart } from '@kbn/core-http-browser';
 
-import './loading_indicator.scss';
-
 export interface LoadingIndicatorProps {
   loadingCount$: ReturnType<HttpStart['getLoadingCount$']>;
   showAsBar?: boolean;
@@ -60,6 +59,12 @@ export class LoadingIndicator extends React.Component<LoadingIndicatorProps, { v
 
   render() {
     const className = classNames(!this.state.visible && 'kbnLoadingIndicator-hidden');
+    const indicatorHiddenCss = !this.state.visible
+      ? css({
+          visibility: 'hidden',
+          animationPlayState: 'paused',
+        })
+      : undefined;
 
     const testSubj = this.state.visible
       ? 'globalLoadingIndicator'
@@ -84,7 +89,6 @@ export class LoadingIndicator extends React.Component<LoadingIndicatorProps, { v
         type={'logoElastic'}
         size="l"
         data-test-subj={testSubj}
-        className="chrHeaderLogo__cluster"
         aria-label={i18n.translate('core.ui.chrome.headerGlobalNav.logoAriaLabel', {
           defaultMessage: 'Elastic Logo',
         })}
@@ -102,18 +106,31 @@ export class LoadingIndicator extends React.Component<LoadingIndicatorProps, { v
       logoImage
     );
 
-    return !this.props.showAsBar ? (
+    return (
-      logo
+      <>
-    ) : (
+        <Global
-      <EuiProgress
+          styles={{
-        className={className}
+            '.euiHeaderSectionItem .euiButtonEmpty__text': {
-        data-test-subj={testSubj}
+              // stop global header buttons from jumping during loading state
-        max={this.props.maxAmount}
+              display: 'flex',
-        value={this.props.valueAmount}
+            },
-        position="fixed"
+          }}
-        color="accent"
+        />
-        size="xs"
+        {!this.props.showAsBar ? (
-      />
+          logo
+        ) : (
+          <EuiProgress
+            className={className}
+            css={indicatorHiddenCss}
+            data-test-subj={testSubj}
+            max={this.props.maxAmount}
+            value={this.props.valueAmount}
+            position="fixed"
+            color="accent"
+            size="xs"
+          />
+        )}
+      </>
     );
   }
 }

packages/shared-ux/chrome/navigation/src/ui/header_logo.scss

@@ -1,4 +0,0 @@
-.chrHeaderLogo__mark {
-  margin-left: $euiSizeS;
-  fill: $euiColorGhost;
-}

x-pack/plugins/security_solution/public/timelines/components/timeline/helpers.tsx

@@ -184,7 +184,7 @@ export const focusUtilityBarAction = (containerElement: HTMLElement | null) => {
  * Resets keyboard focus on the page
  */
 export const resetKeyboardFocus = () => {
-  document.querySelector<HTMLAnchorElement>('header.headerGlobalNav a.chrHeaderLogo')?.focus();
+  document.body.focus();
 };
 
 interface OperatorHandler {

x-pack/test/custom_branding/tests/settings.ts

@@ -91,8 +91,7 @@ export default function ({ getService, getPageObjects }: FtrProviderContext) {
         require.resolve('./acme_text.png')
       );
       await goToSettings();
-      const logo = await testSubjects.find('logo');
+      const img = await testSubjects.find('logoMark');
-      const img = await logo.findByCssSelector('.chrHeaderLogo__mark');
       const imgSrc = (await img.getAttribute('src')) ?? '';
       expect(imgSrc.startsWith('data:image/png')).to.be(true);
     });