chore: setup stricter linting (#3533)

Adds these linting packages:

- eslint-plugin-import: for better import linting
- eslint-plugin-simple-import-sort: for automatic import sorting
- eslint-plugin-wc: for linting web components
- eslint-plugin-lit: for linting lit components

Author: hugo-vrijswijk

libs/eslint-plugin-mte/index.d.ts

@@ -1,4 +1,4 @@
-import type { Linter } from 'eslint';
+import type { config } from 'typescript-eslint';
 
-declare const configs: Linter.FlatConfig[];
+declare const configs: ReturnType<typeof config>;
 export default configs;

libs/eslint-plugin-mte/index.js

@@ -1,32 +1,43 @@
 import eslint from '@eslint/js';
 import eslintConfigPrettier from 'eslint-config-prettier';
-import tseslint from 'typescript-eslint';
+import importX from 'eslint-plugin-import-x';
+import simpleImportSort from 'eslint-plugin-simple-import-sort';
 import globals from 'globals';
+import tseslint from 'typescript-eslint';
 
-/**
- * @type {import('eslint').Linter.FlatConfig[]}
- */
-export default [
+export default tseslint.config(
   eslint.configs.recommended,
   tseslint.configs.eslintRecommended,
   ...tseslint.configs.recommendedTypeChecked,
   ...tseslint.configs.stylisticTypeChecked,
   eslintConfigPrettier,
+  importX.flatConfigs.recommended,
+  importX.flatConfigs.typescript,
   {
     languageOptions: {
       parserOptions: {
         project: ['./tsconfig.json', './{src,test}/tsconfig.json', './test/{unit,integration}/tsconfig.json', '../../tsconfig.node.json'],
       },
     },
+    plugins: {
+      'simple-import-sort': simpleImportSort,
+    },
     linterOptions: {
       reportUnusedDisableDirectives: 'error',
     },
     rules: {
-      eqeqeq: 'error',
+      '@typescript-eslint/consistent-type-imports': 'error',
       '@typescript-eslint/explicit-function-return-type': 'off',
       '@typescript-eslint/explicit-module-boundary-types': 'off',
       '@typescript-eslint/no-unsafe-assignment': 'off',
-      '@typescript-eslint/consistent-type-imports': 'error',
+
+      'import-x/newline-after-import': 'error',
+      'import-x/no-deprecated': 'error',
+
+      'simple-import-sort/exports': 'error',
+      'simple-import-sort/imports': 'error',
+
+      eqeqeq: 'error',
     },
   },
   {
@@ -63,4 +74,4 @@ export default [
       'playwright-report',
     ],
   },
-];
+);

libs/eslint-plugin-mte/package.json

@@ -22,9 +22,12 @@
     "@eslint/js": "^9.0.0",
     "eslint": "^9.0.0",
     "eslint-config-prettier": "~9.1.0",
-    "eslint-plugin-lit": "^1.10.1",
-    "eslint-plugin-wc": "^2.0.4",
-    "typescript-eslint": "8.15.0"
+    "eslint-import-resolver-typescript": "^3.6.3",
+    "eslint-plugin-import-x": "^4.4.3",
+    "eslint-plugin-lit": "^1.15.0",
+    "eslint-plugin-simple-import-sort": "^12.1.1",
+    "eslint-plugin-wc": "^2.2.0",
+    "typescript-eslint": "8.16.0"
   },
   "devDependencies": {}
 }