Lint TypeScript

Uses ESLint (https://eslint.org/) to lint the TypeScript code.

.eslintrc.json

@@ -0,0 +1,36 @@
+{
+  "parser": "@typescript-eslint/parser",
+  "plugins": ["@typescript-eslint", "no-comments"],
+  "extends": [
+    "eslint:recommended",
+    "plugin:@typescript-eslint/strict-type-checked",
+    "plugin:@typescript-eslint/stylistic-type-checked",
+    "plugin:import/recommended",
+    "plugin:import/typescript",
+    "prettier"
+  ],
+  "parserOptions": {
+    "project": "./tsconfig.json"
+  },
+  "rules": {
+    "@typescript-eslint/array-type": ["error", { "default": "generic" }],
+    "@typescript-eslint/consistent-type-imports": ["error", { "fixStyle": "inline-type-imports" }],
+    "@typescript-eslint/no-confusing-void-expression": "off",
+    "@typescript-eslint/no-import-type-side-effects": "error",
+    "@typescript-eslint/prefer-nullish-coalescing": ["error", { "ignoreConditionalTests": true }],
+    "@typescript-eslint/strict-boolean-expressions": "error",
+    "import/no-cycle": "error",
+    "import/no-duplicates": ["error", { "prefer-inline": true }],
+    "import/no-extraneous-dependencies": ["error"],
+    "import/no-internal-modules": ["error"],
+    "import/no-named-as-default": "off",
+    "import/no-named-as-default-member": "off",
+    "no-comments/disallowComments": ["error"],
+    "quotes": ["error", "single", { "avoidEscape": true }]
+  },
+  "settings": {
+    "import/resolver": {
+      "typescript": true
+    }
+  }
+}

.github/workflows/ci.yml

@@ -35,6 +35,27 @@ jobs:
       - name: 'Run formatter'
         run: npx prettier --ignore-unknown --check '**'
 
+  lint:
+    name: 'Lint'
+    runs-on: ubuntu-22.04
+    timeout-minutes: 30
+
+    steps:
+      - name: 'Checkout code'
+        uses: actions/checkout@v4.1.1
+
+      - name: 'Set up Node.js'
+        uses: actions/setup-node@v4.0.0
+        with:
+          node-version-file: package.json
+          cache: ${{ !env.ACT && 'npm' || '' }}
+
+      - name: 'Install dependencies'
+        run: npm ci
+
+      - name: 'Run the linter'
+        run: npx eslint . --max-warnings 0
+
   typecheck:
     name: 'Typecheck'
     runs-on: ubuntu-22.04

Makefile

@@ -1,17 +1,21 @@
-.PHONY: check fix format start typecheck
+.PHONY: check fix format lint start typecheck
 
 node_modules: package.json package-lock.json
 	npm install
 	touch node_modules
 
-check: format typecheck
+check: format lint typecheck
 
 fix: node_modules
+	npx eslint . --fix --max-warnings 0
 	npx prettier --ignore-unknown --write '**'
 
 format: node_modules
 	npx prettier --ignore-unknown --check '**'
 
+lint: node_modules
+	npx eslint . --max-warnings 0
+
 typecheck: node_modules
 	npx tsc --noEmit