Adds UnderlinePanels to drafts/ (#4550)

* adds UnderlinePanels components and stories

stylistic tweaks

more stylistic tweaks

* adds tests, minor stylistic updates

* adds component docs

* adds changeset

* corrects changeset

* fixes circ dep, tests, misc bugs

* more test fixes

* appease the linter

* updates snaps, fixes tiny visual regression

* test(vrt): update snapshots

* cleanup

* upgrades @github/tab-container-element

* fixes createComponent import

* updates jest snapshots

* Apply suggestion from @broccolinisoup

Co-authored-by: Armağan <broccolinisoup@github.com>

* addresses PR feedback

* fix broken import

* addresses more PR feedback

* test(vrt): update snapshots

* test(vrt): update snapshots

* adds fallbacks to CSS vars

* fixes CSS typo

* fixes more typos

---------

Co-authored-by: mperrotti <mperrotti@users.noreply.github.com>
Co-authored-by: Armağan <broccolinisoup@github.com>

.changeset/rotten-apples-hope.md

@@ -0,0 +1,7 @@
+---
+'@primer/react': minor
+---
+
+Adds UnderlinePanels component. It's like UnderlineNav, but for rendering semantic tabs instead of links.
+
+<!-- Changed components: UnderilnePanels -->

e2e/components/UnderlinePanels.test.ts

@@ -0,0 +1,245 @@
+import {test, expect} from '@playwright/test'
+import {visit} from '../test-helpers/storybook'
+import {themes} from '../test-helpers/themes'
+
+test.describe('UnderlinePanels', () => {
+  test.describe('Default', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels--default',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          // Default state
+          expect(await page.screenshot()).toMatchSnapshot(`UnderlineNav.Default.${theme}.png`)
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels--default',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
+
+  test.describe('Labelled By External Element', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--labelled-by-external-element',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          // Default state
+          expect(await page.screenshot()).toMatchSnapshot(`UnderlineNav.Labelled By External Element.${theme}.png`)
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--labelled-by-external-element',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
+
+  test.describe('Selected Tab', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--selected-tab',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          // Default state
+          expect(await page.screenshot()).toMatchSnapshot(`UnderlineNav.Selected Tab.${theme}.png`)
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--selected-tab',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
+
+  test.describe('With Counters', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-counters',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          // Default state
+          expect(await page.screenshot()).toMatchSnapshot(`UnderlineNav.With Counters.${theme}.png`)
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-counters',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
+
+  test.describe('With Counters In Loading State', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-counters-in-loading-state',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          // Default state
+          expect(await page.screenshot()).toMatchSnapshot(`UnderlineNav.With Counters In Loading State.${theme}.png`)
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-counters-in-loading-state',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
+
+  test.describe('With Icons', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-icons',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          // Default state
+          expect(await page.screenshot()).toMatchSnapshot(`UnderlineNav.With Icons.${theme}.png`)
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-icons',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
+
+  test.describe('With Icons Hidden On Narrow Screen', () => {
+    for (const theme of themes) {
+      test.describe(theme, () => {
+        test('default @vrt', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-icons-hidden-on-narrow-screen',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+
+          // Default state
+          expect(await page.screenshot()).toMatchSnapshot(
+            `UnderlineNav.With Icons Hidden On Narrow Screen.${theme}.png`,
+          )
+        })
+
+        test('axe @aat', async ({page}) => {
+          await visit(page, {
+            id: 'drafts-components-underlinepanels-features--with-icons-hidden-on-narrow-screen',
+            globals: {
+              colorScheme: theme,
+            },
+          })
+          await expect(page).toHaveNoViolations({
+            rules: {
+              'color-contrast': {
+                enabled: theme !== 'dark_dimmed',
+              },
+            },
+          })
+        })
+      })
+    }
+  })
+})