ci: setup eslint workflow (#231)

* ci: preliminary eslint configuration

* chore: clean up unused ignore directives

* ci: add lint workflow to ci

* ci: fix monorepo tslint configuration

* chore: resolve lint warning for no-unnecessary-type-assertion

* chore: resolve prefer-const lint error

* chore: run prettier lint

* chore: remove typeroots to resolve node:path warnings

* chore: rebuild per-file suppressions

* chore: remove excessive suppressions

Author: mrstork

.eslintrc.js

@@ -0,0 +1,29 @@
+name: Lint
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+    types: [opened, synchronize, reopened]
+
+jobs:
+  lint:
+    name: Lint
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+
+      - name: Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: lts/*
+          cache: 'npm'
+
+      - name: Install dependencies
+        run: npm ci --no-audit
+
+      - name: Lint
+        run: npm run lint

.github/workflows/lint.yaml

@@ -0,0 +1,111 @@
+// @ts-check
+import * as path from 'node:path'
+import { fileURLToPath } from 'node:url'
+import { includeIgnoreFile } from '@eslint/compat'
+import eslint from '@eslint/js'
+import node from 'eslint-plugin-n'
+import prettier from 'eslint-config-prettier'
+import tseslint from 'typescript-eslint'
+import vitest from '@vitest/eslint-plugin'
+
+import temporarySuppressions from './eslint_temporary_suppressions.js'
+
+const __filename = fileURLToPath(import.meta.url)
+const __dirname = path.dirname(__filename)
+
+export default tseslint.config(
+  // Global rules and configuration
+  includeIgnoreFile(path.resolve(__dirname, '.gitignore')),
+  {
+    linterOptions: {
+      reportUnusedDisableDirectives: true,
+    },
+  },
+
+  // JavaScript-specific rules
+  eslint.configs.recommended,
+
+  // Typescript-specific rules
+  tseslint.configs.strictTypeChecked,
+  tseslint.configs.stylisticTypeChecked,
+  {
+    languageOptions: {
+      parserOptions: {
+        project: ['./tsconfig.base.json', './packages/*/tsconfig.json'],
+        tsconfigRootDir: __dirname,
+      },
+    },
+  },
+
+  {
+    files: ['**/*.?(c|m)js?(x)'],
+    ...tseslint.configs.disableTypeChecked,
+  },
+  node.configs['flat/recommended'],
+  {
+    rules: {
+      'n/no-extraneous-import': 'off',
+      'n/no-extraneous-require': 'off',
+      'n/no-missing-import': 'off',
+      'n/no-missing-require': 'off',
+      'n/no-unpublished-import': 'off',
+      'n/no-unpublished-require': 'off',
+    },
+  },
+
+  // Project-specific rules
+  {
+    files: ['**/*.?(c|m)ts?(x)'],
+    rules: {
+      // `interface` and `type` have different use cases, allow both
+      '@typescript-eslint/consistent-type-definitions': 'off',
+
+      // Ignore underscore-prefixed unused variables (mirrors tsc behavior)
+      '@typescript-eslint/no-unused-vars': [
+        'error',
+        {
+          args: 'all',
+          argsIgnorePattern: '^_',
+          caughtErrors: 'all',
+          caughtErrorsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+          ignoreRestSiblings: true,
+          varsIgnorePattern: '^_',
+        },
+      ],
+    },
+  },
+
+  // Tests
+  {
+    files: ['**/*.test.?(c|m)[jt]s?(x)'],
+    plugins: { vitest },
+    rules: {
+      ...vitest.configs.recommended.rules,
+
+      'vitest/expect-expect': [
+        'error',
+        {
+          assertFunctionNames: [
+            // Defaults
+            'assert',
+            'expect',
+
+            // Fix issue where text-context-specific `expect()` calls trigger false positive
+            't.expect',
+            'ctx.expect',
+            'context.expect',
+
+            // Custom assertion functions
+            'assertNetlifyToml',
+          ],
+        },
+      ],
+    },
+  },
+
+  ...temporarySuppressions,
+
+  // Must be last
+  prettier,
+)