fix: add type tests

.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

package.json

@@ -51,7 +51,8 @@
     "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",

src/index.js

@@ -35,11 +35,11 @@ const plugin = {
 	configs: {
 		recommended: {
 			plugins: {},
-			rules: {
+			rules: /** @type {const} */ ({
 				"json/no-duplicate-keys": "error",
 				"json/no-empty-keys": "error",
 				"json/no-unsafe-values": "error",
-			},
+			}),
 		},
 	},
 };

src/rules/no-duplicate-keys.js

@@ -9,7 +9,7 @@
 
 export default {
 	meta: {
-		type: "problem",
+		type: /** @type {const} */ ("problem"),
 
 		docs: {
 			description: "Disallow duplicate keys in JSON objects",

src/rules/no-empty-keys.js

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

src/rules/no-unsafe-values.js

@@ -5,7 +5,7 @@
 
 export default {
 	meta: {
-		type: "problem",
+		type: /** @type {const} */ ("problem"),
 
 		docs: {
 			description: "Disallow JSON values that are unsafe for interchange",

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 +1,23 @@
+import json from "@eslint/json";
+import { ESLint } from "eslint";
+
+json satisfies ESLint.Plugin;
+json.meta.name satisfies string;
+json.meta.version satisfies string;
+
+// Check that these languages are defined:
+json.languages.json satisfies object;
+json.languages.json5 satisfies object;
+json.languages.jsonc satisfies object;
+
+// Check that `plugins` in the recommended config is defined:
+json.configs.recommended.plugins satisfies object;
+
+{
+	type RecommendedRuleName = keyof typeof json.configs.recommended.rules;
+	type RuleName = `json/${keyof typeof json.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>;
+}