Add type checking job to the CI workflow (#1827)

Co-authored-by: Chris Swithinbank <swithinbank@gmail.com>

11 files changed, 61 insertions, 22 deletions

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index beb12cf4..5b7a5b94 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -44,6 +44,23 @@ jobs:
       - name: Test packages
         run: pnpm -r test:e2e
 
+  type-check:
+    name: Run type checks
+    runs-on: ubuntu-20.04
+    steps:
+      - uses: actions/checkout@v4
+      - uses: pnpm/action-setup@v3
+      - uses: actions/setup-node@v4
+        with:
+          node-version: ${{ env.NODE_VERSION }}
+          cache: 'pnpm'
+      - run: pnpm i
+      - name: Generate docs types
+        working-directory: docs
+        run: pnpm astro sync
+      - name: Type check packages
+        run: pnpm typecheck
+
   pa11y:
     name: Check for accessibility issues
     runs-on: ubuntu-20.04
diff --git a/package.json b/package.json
index 8e0fd9e6..b730b6c7 100644
--- a/package.json
+++ b/package.json
@@ -7,7 +7,8 @@
     "build:examples": "pnpm --no-bail --workspace-concurrency 1 --filter '@example/*' build",
     "size": "size-limit",
     "version": "pnpm changeset version && pnpm i --no-frozen-lockfile",
-    "format": "prettier -w --cache --plugin prettier-plugin-astro ."
+    "format": "prettier -w --cache --plugin prettier-plugin-astro .",
+    "typecheck": "tsc -p tsconfig.typecheck.json"
   },
   "license": "MIT",
   "devDependencies": {
@@ -17,6 +18,7 @@
     "astro": "^4.3.5",
     "prettier": "^3.0.0",
     "prettier-plugin-astro": "^0.13.0",
+    "typescript": "^5.4.5",
     "size-limit": "^8.2.4"
   },
   "packageManager": "pnpm@8.7.4",
diff --git a/packages/starlight/__tests__/basics/route-data.test.ts b/packages/starlight/__tests__/basics/route-data.test.ts
index eacd5334..d59ce013 100644
--- a/packages/starlight/__tests__/basics/route-data.test.ts
+++ b/packages/starlight/__tests__/basics/route-data.test.ts
@@ -7,6 +7,7 @@ vi.mock('astro:content', async () =>
 		docs: [
 			['index.mdx', { title: 'Home Page' }],
 			['getting-started.mdx', { title: 'Splash', template: 'splash' }],
+			// @ts-expect-error — Using a slug not present in Starlight docs site
 			['showcase.mdx', { title: 'ToC Disabled', tableOfContents: false }],
 			['environmental-impact.md', { title: 'Explicit update date', lastUpdated: new Date() }],
 		],
diff --git a/packages/starlight/__tests__/basics/starlight-page-route-data-extend.test.ts b/packages/starlight/__tests__/basics/starlight-page-route-data-extend.test.ts
index 3ab5b8f5..23438c7a 100644
--- a/packages/starlight/__tests__/basics/starlight-page-route-data-extend.test.ts
+++ b/packages/starlight/__tests__/basics/starlight-page-route-data-extend.test.ts
@@ -1,4 +1,4 @@
-import { assert, expect, test, vi } from 'vitest';
+import { expect, test, vi } from 'vitest';
 import {
 	generateStarlightPageRouteData,
 	type StarlightPageProps,
diff --git a/packages/starlight/__tests__/edit-url/edit-url.test.ts b/packages/starlight/__tests__/edit-url/edit-url.test.ts
index 25ab98aa..c77aa93d 100644
--- a/packages/starlight/__tests__/edit-url/edit-url.test.ts
+++ b/packages/starlight/__tests__/edit-url/edit-url.test.ts
@@ -8,6 +8,7 @@ vi.mock('astro:content', async () =>
 			['index.mdx', { title: 'Home Page' }],
 			['getting-started.mdx', { title: 'Getting Started' }],
 			[
+				// @ts-expect-error — Using a slug not present in Starlight docs site
 				'showcase.mdx',
 				{ title: 'Custom edit link', editUrl: 'https://example.com/custom-edit?link' },
 			],
diff --git a/packages/starlight/__tests__/i18n-non-root-single-locale/routing.test.ts b/packages/starlight/__tests__/i18n-non-root-single-locale/routing.test.ts
index 2caef2f5..11058ec0 100644
--- a/packages/starlight/__tests__/i18n-non-root-single-locale/routing.test.ts
+++ b/packages/starlight/__tests__/i18n-non-root-single-locale/routing.test.ts
@@ -5,6 +5,7 @@ vi.mock('astro:content', async () =>
 	(await import('../test-utils')).mockedAstroContent({
 		docs: [
 			['fr/index.mdx', { title: 'Accueil' }],
+			// @ts-expect-error — Using a slug not present in Starlight docs site
 			['en/index.mdx', { title: 'Home page' }],
 		],
 	})
diff --git a/packages/starlight/utils/createPathFormatter.ts b/packages/starlight/utils/createPathFormatter.ts
index af363186..f4db6f7a 100644
--- a/packages/starlight/utils/createPathFormatter.ts
+++ b/packages/starlight/utils/createPathFormatter.ts
@@ -34,6 +34,7 @@ function formatPath(
 	href: string,
 	{ format = 'directory', trailingSlash = 'ignore' }: FormatPathOptions
 ) {
+	// @ts-expect-error — TODO: add support for `preserve` (https://github.com/withastro/starlight/issues/1781)
 	const formatStrategy = formatStrategies[format];
 	const trailingSlashStrategy = trailingSlashStrategies[trailingSlash];
 
diff --git a/packages/starlight/utils/user-config.ts b/packages/starlight/utils/user-config.ts
index 31f00077..efd6193e 100644
--- a/packages/starlight/utils/user-config.ts
+++ b/packages/starlight/utils/user-config.ts
@@ -256,7 +256,7 @@ export const StarlightConfigSchema = UserConfigSchema.strict().transform(
 		const defaultLocaleConfig = {
 			label: 'English',
 			lang: 'en',
-			dir: 'ltr',
+			dir: 'ltr' as const,
 			locale: undefined,
 			...locales?.root,
 		};
diff --git a/packages/tailwind/vitest.config.ts b/packages/tailwind/vitest.config.ts
index b29e52cd..f32a3d0b 100644
--- a/packages/tailwind/vitest.config.ts
+++ b/packages/tailwind/vitest.config.ts
@@ -4,11 +4,13 @@ export default defineConfig({
 	test: {
 		coverage: {
 			reportsDirectory: './__coverage__',
-			thresholdAutoUpdate: true,
-			lines: 100,
-			functions: 100,
-			branches: 100,
-			statements: 100,
+			thresholds: {
+				autoUpdate: true,
+				lines: 94,
+				functions: 100,
+				branches: 85,
+				statements: 94,
+			},
 		},
 	},
 });
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 1094b3f4..032db9c1 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -19,7 +19,7 @@ importers:
         version: 8.2.4(size-limit@8.2.4)
       astro:
         specifier: ^4.3.5
-        version: 4.3.5(@types/node@18.16.19)
+        version: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       prettier:
         specifier: ^3.0.0
         version: 3.0.0
@@ -29,6 +29,9 @@ importers:
       size-limit:
         specifier: ^8.2.4
         version: 8.2.4
+      typescript:
+        specifier: ^5.4.5
+        version: 5.4.5
 
   docs:
     dependencies:
@@ -46,7 +49,7 @@ importers:
         version: 2.0.0
       astro:
         specifier: ^4.3.5
-        version: 4.3.5(@types/node@18.16.19)
+        version: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       culori:
         specifier: ^3.2.0
         version: 3.2.0
@@ -71,7 +74,7 @@ importers:
         version: link:../../packages/starlight
       astro:
         specifier: ^4.3.5
-        version: 4.3.5(@types/node@18.16.19)
+        version: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       sharp:
         specifier: ^0.32.5
         version: 0.32.6
@@ -89,7 +92,7 @@ importers:
         version: 5.1.0(astro@4.3.5)(tailwindcss@3.4.1)
       astro:
         specifier: ^4.3.5
-        version: 4.3.5(@types/node@18.16.19)
+        version: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       sharp:
         specifier: ^0.32.5
         version: 0.32.6
@@ -196,7 +199,7 @@ importers:
         version: 1.3.1(vitest@1.3.1)
       astro:
         specifier: ^4.3.5
-        version: 4.3.5(@types/node@18.16.19)
+        version: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       vitest:
         specifier: ^1.3.1
         version: 1.3.1(@types/node@18.16.19)
@@ -208,7 +211,7 @@ importers:
         version: link:../../..
       astro:
         specifier: ^4.3.5
-        version: 4.3.5(@types/node@18.16.19)
+        version: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
 
   packages/tailwind:
     dependencies:
@@ -385,7 +388,7 @@ packages:
     peerDependencies:
       astro: ^2.0.0 || ^3.0.0-beta || ^4.0.0-beta
     dependencies:
-      astro: 4.3.5(@types/node@18.16.19)
+      astro: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       lite-youtube-embed: 0.2.0
     dev: false
 
@@ -428,7 +431,7 @@ packages:
       '@astrojs/markdown-remark': 4.2.1
       '@mdx-js/mdx': 3.0.0
       acorn: 8.11.3
-      astro: 4.3.5(@types/node@18.16.19)
+      astro: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       es-module-lexer: 1.4.1
       estree-util-visit: 2.0.0
       github-slugger: 2.0.0
@@ -464,7 +467,7 @@ packages:
       astro: ^3.0.0 || ^4.0.0
       tailwindcss: ^3.0.24
     dependencies:
-      astro: 4.3.5(@types/node@18.16.19)
+      astro: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       autoprefixer: 10.4.15(postcss@8.4.33)
       postcss: 8.4.33
       postcss-load-config: 4.0.2(postcss@8.4.33)
@@ -1856,11 +1859,11 @@ packages:
     peerDependencies:
       astro: ^4.0.0-beta || ^3.3.0
     dependencies:
-      astro: 4.3.5(@types/node@18.16.19)
+      astro: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       rehype-expressive-code: 0.35.2
     dev: false
 
-  /astro@4.3.5(@types/node@18.16.19):
+  /astro@4.3.5(@types/node@18.16.19)(typescript@5.4.5):
     resolution: {integrity: sha512-7jPffNlcmDO94NlkWe/hUWta/pIjlx1LVD/DZb/fyjT1Jv+7mGhKZBIjkDfeVpequW70mep8cAS5RM7Pxa0Gdg==}
     engines: {node: '>=18.14.1', npm: '>=6.14.0'}
     hasBin: true
@@ -1921,7 +1924,7 @@ packages:
       shikiji: 0.9.19
       string-width: 7.0.0
       strip-ansi: 7.1.0
-      tsconfck: 3.0.0
+      tsconfck: 3.0.0(typescript@5.4.5)
       unist-util-visit: 5.0.0
       vfile: 6.0.1
       vite: 5.0.12(@types/node@18.16.19)
@@ -6013,7 +6016,7 @@ packages:
       astro: '>=4.0.0'
     dependencies:
       '@astrojs/starlight': link:packages/starlight
-      astro: 4.3.5(@types/node@18.16.19)
+      astro: 4.3.5(@types/node@18.16.19)(typescript@5.4.5)
       github-slugger: 2.0.0
       hast-util-from-html: 2.0.1
       hast-util-has-property: 3.0.0
@@ -6394,7 +6397,7 @@ packages:
     resolution: {integrity: sha512-Y/arvbn+rrz3JCKl9C4kVNfTfSm2/mEp5FSz5EsZSANGPSlQrpRI5M4PKF+mJnE52jOO90PnPSc3Ur3bTQw0gA==}
     dev: false
 
-  /tsconfck@3.0.0:
+  /tsconfck@3.0.0(typescript@5.4.5):
     resolution: {integrity: sha512-w3wnsIrJNi7avf4Zb0VjOoodoO0woEqGgZGQm+LHH9przdUI+XDKsWAXwxHA1DaRTjeuZNcregSzr7RaA8zG9A==}
     engines: {node: ^18 || >=20}
     hasBin: true
@@ -6403,6 +6406,8 @@ packages:
     peerDependenciesMeta:
       typescript:
         optional: true
+    dependencies:
+      typescript: 5.4.5
 
   /tslib@2.5.0:
     resolution: {integrity: sha512-336iVw3rtn2BUK7ORdIAHTyxHGRIHVReokCR3XjbckJMK7ms8FysBfhLR8IXnAgy7T0PTPNBWKiH514FOW/WSg==}
@@ -6470,6 +6475,11 @@ packages:
       is-typed-array: 1.1.10
     dev: true
 
+  /typescript@5.4.5:
+    resolution: {integrity: sha512-vcI4UpRgg81oIRUFwR0WSIHKt11nJ7SAVlYNIu+QpqeyXP+gpQJy/Z4+F0aGxSE4MqwjyXvW/TzgkLAx2AGHwQ==}
+    engines: {node: '>=14.17'}
+    hasBin: true
+
   /ufo@1.3.2:
     resolution: {integrity: sha512-o+ORpgGwaYQXgqGDwd+hkS4PuZ3QnmqMMxRuajK/a38L6fTpcE5GPIfrf+L/KemFzfUpeUQc1rRS1iDBozvnFA==}
     dev: true
diff --git a/tsconfig.typecheck.json b/tsconfig.typecheck.json
new file mode 100644
index 00000000..1327de77
--- /dev/null
+++ b/tsconfig.typecheck.json
@@ -0,0 +1,4 @@
+{
+  "extends": "./tsconfig.json",
+  "exclude": ["**/dist/**", "**/__coverage__/**", "packages/starlight/components.ts"]
+}