chore: update to eslint v9

Author: 06kellyjac

.eslintrc.json

@@ -0,0 +1,169 @@
+// @ts-check
+import { fileURLToPath } from 'node:url';
+import { includeIgnoreFile } from '@eslint/compat';
+import { defineConfig } from 'eslint/config';
+import globals from 'globals';
+import js from '@eslint/js';
+import ts from 'typescript-eslint';
+import react from 'eslint-plugin-react';
+import json from '@eslint/json';
+// @ts-expect-error
+import cypress from 'eslint-plugin-cypress';
+import prettierConfig from 'eslint-config-prettier/flat';
+
+// paths shouldn't start with ./
+
+const gitignorePath = fileURLToPath(
+  new URL(
+    '.gitignore',
+    // @ts-expect-error ts doesn't respect this file as a module, can ignore
+    import.meta.url,
+  ),
+);
+
+export default defineConfig(
+  includeIgnoreFile(gitignorePath, 'Imported .gitignore patterns'),
+  {
+    name: 'ignores',
+    ignores: [
+      // lock files we don't control
+      '**/package-lock.json',
+      // has it's own eslint
+      'experimental/license-inventory',
+      // vendored code we're not changing
+      'src/ui/assets/js/**',
+      'src/ui/assets/css/**',
+    ],
+  },
+
+  {
+    name: 'JSON',
+    files: ['**/*.json'],
+    plugins: { json },
+    extends: [json.configs.recommended],
+    language: 'json/json',
+  },
+
+  {
+    name: 'JSON - proxy.config.json override',
+    files: ['**/proxy.config.json'],
+    // allow empty keys in proxy.config.json for now
+    rules: { 'json/no-empty-keys': 'off' },
+  },
+
+  // attempt at accurately linting each "type" of code we have
+  // much of this can be consolidated going forward, or split out in
+  // the case of the frontend
+  {
+    name: 'JS',
+    files: ['**/*.{js,jsx,mjs,cjs,ts,tsx}'],
+    plugins: { js },
+    extends: [js.configs.recommended],
+    languageOptions: {
+      globals: {
+        ...globals.node,
+        // allow commonjs during the migration
+        ...globals.commonjs,
+      },
+    },
+    rules: { 'no-unused-vars': 'warn', 'no-undef': 'warn', 'guard-for-in': 'error' },
+  },
+
+  {
+    name: 'TS',
+    files: ['**/*.{js,jsx,ts,tsx}'],
+    plugins: { '@typescript-eslint': ts.plugin },
+    extends: [ts.configs.recommended],
+    languageOptions: { globals: { ...globals.node } },
+    rules: {
+      'no-async-promise-executor': 'warn', // to resolve and return to default
+      '@typescript-eslint/no-explicit-any': 'off', // temporary until TS refactor is complete
+      // '@typescript-eslint/no-unused-vars': 'off', // temporary until TS refactor is complete
+      // "no-unused-vars": 'off',
+      '@typescript-eslint/no-unused-vars': [
+        // TODO: increase this to error
+        'off',
+        {
+          // allow ignoring/skipping a var with a _ prefix
+          // also allow for `...otherStuff` syntax, particularly common in react
+          argsIgnorePattern: '^_',
+          caughtErrorsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          ignoreRestSiblings: true,
+        },
+      ],
+      '@typescript-eslint/no-require-imports': 'off', // prevents error on old "require" imports
+    },
+  },
+
+  {
+    name: 'JS minus type checking',
+    // disable type-aware linting on JS files
+    files: ['**/*.js'],
+    extends: [ts.configs.disableTypeChecked],
+  },
+
+  // web/react content
+  {
+    name: 'web/react',
+    files: [
+      'src/ui/**/*.{js,jsx,mjs,cjs,ts,tsx}',
+      // TODO: split website into separate linting
+      'website/src/**/*.{js,jsx,mjs,cjs,ts,tsx}',
+    ],
+    plugins: { react },
+    extends: [react.configs.flat.recommended],
+    languageOptions: { globals: { ...globals.browser, ...globals.commonjs } },
+    settings: { react: { version: 'detect' } },
+    rules: {
+      'react/jsx-uses-react': 'error',
+      'react/jsx-uses-vars': 'error',
+      'react/prop-types': 'off',
+    },
+  },
+
+  // tests
+  {
+    name: 'tests',
+    files: ['**/*.test.{js,mjs,cjs}'],
+    languageOptions: {
+      // allow global functions e.g. describe, it, expect, etc.
+      // from mocha and chai in tests
+      globals: { ...globals.mocha, ...globals.chai },
+    },
+    rules: {
+      '@typescript-eslint/no-unused-vars': [
+        // TODO: increase to 'error'
+        'warn',
+        {
+          argsIgnorePattern: '^_',
+          caughtErrorsIgnorePattern: '^_',
+          destructuredArrayIgnorePattern: '^_',
+          varsIgnorePattern: '^_',
+          ignoreRestSiblings: true,
+          // same as rule above but exclude unused error vars in try catch for
+          // now due to many warnings in tests
+          caughtErrors: 'none',
+        },
+      ],
+      // allow for chai `expect().to.xyz`
+      '@typescript-eslint/no-unused-expressions': 'off',
+    },
+  },
+
+  // cypress e2e tests
+  {
+    name: 'cypress',
+    files: ['cypress/**/*.{js,mjs,cjs,ts}'],
+    extends: [cypress.configs.recommended],
+    rules: {
+      // TODO: fix and remove 'warn' override
+      'cypress/unsafe-to-chain-command': 'warn',
+    },
+  },
+
+  // disables rules which prettier controls
+  // https://prettier.io/docs/integrating-with-linters
+  prettierConfig,
+);