fix: add type tests (#16)

* fix: add type tests

* match formatting to Prettier 3.4

.github/PULL_REQUEST_TEMPLATE.md

@@ -6,7 +6,7 @@
 
 #### Prerequisites checklist
 
--   [ ] I have read the [contributing guidelines](https://github.com/eslint/eslint/blob/HEAD/CONTRIBUTING.md).
+- [ ] I have read the [contributing guidelines](https://github.com/eslint/eslint/blob/HEAD/CONTRIBUTING.md).
 
 <!--
     Please ensure your pull request is ready:

.github/workflows/ci.yml

@@ -45,6 +45,21 @@ jobs:
               run: npm install
             - name: Run tests
               run: npm run test
+    test_types:
+        name: Test Types
+        runs-on: ubuntu-latest
+        steps:
+            - uses: actions/checkout@v4
+            - name: Setup Node.js
+              uses: actions/setup-node@v4
+              with:
+                  node-version: "lts/*"
+            - name: Install dependencies
+              run: npm install
+            - name: Build
+              run: npm run build
+            - name: Check Types
+              run: npm run test:types
     jsr_test:
         name: Verify JSR Publish
         runs-on: ubuntu-latest

docs/rules/no-duplicate-imports.md

@@ -38,4 +38,4 @@ If you aren't concerned with duplicate `@import` rules, you can safely disable t
 
 ## Prior Art
 
--   [`no-duplicate-at-import-rules`](https://stylelint.io/user-guide/rules/no-duplicate-at-import-rules)
+- [`no-duplicate-at-import-rules`](https://stylelint.io/user-guide/rules/no-duplicate-at-import-rules)

docs/rules/no-empty-blocks.md

@@ -51,5 +51,5 @@ If you aren't concerned with empty blocks, you can safely disable this rule.
 
 ## Prior Art
 
--   [empty-rules](https://github.com/CSSLint/csslint/wiki/Disallow-empty-rules)
--   [`block-no-empty`](https://stylelint.io/user-guide/rules/block-no-empty)
+- [empty-rules](https://github.com/CSSLint/csslint/wiki/Disallow-empty-rules)
+- [`block-no-empty`](https://stylelint.io/user-guide/rules/block-no-empty)

docs/rules/no-invalid-at-rules.md

@@ -6,14 +6,14 @@ Disallow invalid at-rules.
 
 CSS contains a number of at-rules, each beginning with a `@`, that perform various operations. Some common at-rules include:
 
--   `@import`
--   `@media`
--   `@font-face`
--   `@keyframes`
--   `@supports`
--   `@namespace`
--   `@page`
--   `@charset`
+- `@import`
+- `@media`
+- `@font-face`
+- `@keyframes`
+- `@supports`
+- `@namespace`
+- `@page`
+- `@charset`
 
 It's important to use a known at-rule because unknown at-rules cause the browser to ignore the entire block, including any rules contained within. For example:
 
@@ -40,10 +40,10 @@ Here, `--main-bg-color` is the prelude for `@property` while `syntax`, `inherits
 
 This rule warns when it finds a CSS at-rule that is unknown or invalid according to the CSS specification. As such, the rule warns for the following problems:
 
--   An unknown at-rule
--   An invalid prelude for a known at-rule
--   An unknown descriptor for a known at-rule
--   An invalid descriptor value for a known at-rule
+- An unknown at-rule
+- An invalid prelude for a known at-rule
+- An unknown descriptor for a known at-rule
+- An invalid descriptor value for a known at-rule
 
 The at-rule data is provided via the [CSSTree](https://github.com/csstree/csstree) project.
 
@@ -77,4 +77,4 @@ If you are purposely using at-rules that aren't part of the CSS specification, t
 
 ## Prior Art
 
--   [`at-rule-no-unknown`](https://stylelint.io/user-guide/rules/at-rule-no-unknown)
+- [`at-rule-no-unknown`](https://stylelint.io/user-guide/rules/at-rule-no-unknown)

docs/rules/no-invalid-properties.md

@@ -48,6 +48,6 @@ If you aren't concerned with invalid properties, then you can safely disable thi
 
 ## Prior Art
 
--   [`declaration-property-value-no-unknown`](https://stylelint.io/user-guide/rules/declaration-property-value-no-unknown/)
+- [`declaration-property-value-no-unknown`](https://stylelint.io/user-guide/rules/declaration-property-value-no-unknown/)
 
--   [`property-no-unknown`](https://stylelint.io/user-guide/rules/property-no-unknown)
+- [`property-no-unknown`](https://stylelint.io/user-guide/rules/property-no-unknown)

package.json

@@ -57,7 +57,8 @@
     "fmt": "prettier --write .",
     "fmt:check": "prettier --check .",
     "test": "mocha tests/**/*.js",
-    "test:coverage": "c8 npm test"
+    "test:coverage": "c8 npm test",
+    "test:types": "tsc -p tests/types/tsconfig.json"
   },
   "keywords": [
     "eslint",
@@ -84,7 +85,7 @@
     "lint-staged": "^15.2.7",
     "mdast-util-from-markdown": "^2.0.2",
     "mocha": "^10.4.0",
-    "prettier": "^3.3.2",
+    "prettier": "^3.4.1",
     "rollup": "^4.16.2",
     "rollup-plugin-copy": "^3.5.0",
     "typescript": "^5.4.5",

src/index.js

@@ -32,20 +32,23 @@ const plugin = {
 		"no-invalid-at-rules": noInvalidAtRules,
 		"no-invalid-properties": noInvalidProperties,
 	},
-	configs: {},
-};
-
-Object.assign(plugin.configs, {
-	recommended: {
-		plugins: { css: plugin },
-		rules: {
-			"css/no-empty-blocks": "error",
-			"css/no-duplicate-imports": "error",
-			"css/no-invalid-at-rules": "error",
-			"css/no-invalid-properties": "error",
+	configs: {
+		recommended: {
+			plugins: {},
+			rules: /** @type {const} */ ({
+				"css/no-empty-blocks": "error",
+				"css/no-duplicate-imports": "error",
+				"css/no-invalid-at-rules": "error",
+				"css/no-invalid-properties": "error",
+			}),
 		},
 	},
-});
+};
+
+// eslint-disable-next-line no-lone-blocks -- The block syntax { ... } ensures that TypeScript does not get confused about the type of `plugin`.
+{
+	plugin.configs.recommended.plugins.css = plugin;
+}
 
 export default plugin;
 export { CSSLanguage, CSSSourceCode };

src/rules/no-duplicate-imports.js

@@ -5,7 +5,7 @@
 
 export default {
 	meta: {
-		type: "problem",
+		type: /** @type {const} */ ("problem"),
 
 		docs: {
 			description: "Disallow duplicate @import rules",

src/rules/no-empty-blocks.js

@@ -5,7 +5,7 @@
 
 export default {
 	meta: {
-		type: "problem",
+		type: /** @type {const} */ ("problem"),
 
 		docs: {
 			description: "Disallow empty blocks",

src/rules/no-invalid-at-rules.js

@@ -44,7 +44,7 @@ function extractMetaDataFromError(error) {
 
 export default {
 	meta: {
-		type: "problem",
+		type: /** @type {const} */ ("problem"),
 
 		docs: {
 			description: "Disallow invalid at-rules",

src/rules/no-invalid-properties.js

@@ -16,7 +16,7 @@ import { isSyntaxMatchError } from "../util.js";
 
 export default {
 	meta: {
-		type: "problem",
+		type: /** @type {const} */ ("problem"),
 
 		docs: {
 			description: "Disallow invalid properties",

tests/types/tsconfig.json

@@ -0,0 +1,9 @@
+{
+  "extends": "../../tsconfig.json",
+  "compilerOptions": {
+    "noEmit": true,
+    "rootDir": "../..",
+    "strict": true
+  },
+  "files": ["../../dist/esm/index.d.ts", "types.test.ts"]
+}

tests/types/types.test.ts

@@ -0,0 +1,21 @@
+import css from "@eslint/css";
+import { ESLint } from "eslint";
+
+css satisfies ESLint.Plugin;
+css.meta.name satisfies string;
+css.meta.version satisfies string;
+
+// Check that these languages are defined:
+css.languages.css satisfies object;
+
+// Check that `plugins` in the recommended config is defined:
+css.configs.recommended.plugins satisfies object;
+
+{
+	type RecommendedRuleName = keyof typeof css.configs.recommended.rules;
+	type RuleName = `css/${keyof typeof css.rules}`;
+	type AssertAllNamesIn<T1 extends T2, T2> = never;
+
+	// Check that all recommended rule names match the names of existing rules in this plugin.
+	null as AssertAllNamesIn<RecommendedRuleName, RuleName>;
+}