chore: Eslint migration foundation + migrate npm/grep package

guides/eslint-migration.md

@@ -0,0 +1,339 @@
+# ESLint Migration Guide: Monorepo Alignment
+
+## Migration Checklist
+
+### Batch 1: Small npm utilities
+- [x] npm/grep ✅ **COMPLETED** - Uses unified ESLint config with package-specific lint-staged handling
+- [ ] npm/puppeteer
+- [ ] npm/mount-utils
+- [ ] npm/cypress-schematic
+
+### Batch 2: Framework adapters
+- [ ] npm/react
+- [ ] npm/vue
+- [ ] npm/svelte
+
+### Batch 3: Build-related
+- [ ] npm/webpack-batteries-included-preprocessor
+- [ ] npm/webpack-preprocessor
+- [ ] npm/webpack-dev-server
+- [ ] npm/vite-plugin-cypress-esm
+- [ ] npm/vite-dev-server
+
+### Batch 4a: Core packages (part 1)
+- [ ] packages/frontend-shared
+- [ ] packages/icons
+- [ ] packages/launcher
+- [ ] packages/https-proxy
+- [ ] packages/proxy
+- [ ] packages/net-stubbing
+- [ ] packages/driver
+- [ ] packages/rewriter
+- [ ] packages/reporter
+- [ ] packages/server
+
+### Batch 4b: Core packages (part 2)
+- [ ] packages/runner
+- [ ] packages/extension
+- [ ] packages/graphql
+- [ ] packages/network
+- [ ] packages/socket
+- [ ] packages/telemetry
+- [ ] packages/launchpad
+- [ ] packages/errors
+- [ ] packages/data-context
+- [ ] packages/app
+
+### Batch 4c: Core packages (part 3)
+- [ ] packages/config
+- [ ] packages/root
+- [ ] packages/resolve-dist
+- [ ] packages/packherd-require
+- [ ] packages/v8-snapshot-require
+- [ ] packages/web-config
+- [ ] packages/types
+- [ ] packages/example
+
+### Batch 5: Test and script folders
+- [ ] system-tests
+- [ ] scripts
+
+---
+
+This guide describes how to migrate all packages in the Cypress monorepo to the new unified ESLint configuration (`@packages/eslint-config`).
+
+---
+
+## Why Migrate?
+- **Consistency:** Enforce the same linting rules and plugins across all packages.
+- **Simplicity:** Remove the need for custom plugins like `@cypress/eslint-plugin-dev`.
+- **Maintainability:** Make it easier to update and maintain lint rules.
+- **Modernization:** Replace obsolete TSLint with the appropriate ESLint TypeScript plugin (`@typescript-eslint`).
+
+---
+
+## Migration Strategy
+
+### 1. **Lint-Staged Configuration**
+During the migration period, the root `package.json` uses explicit lint-staged patterns to ensure each package gets the correct linting treatment:
+
+- **Migrated packages** (like `npm/grep`): Use `yarn lint:fix` which runs ESLint from the package directory with the correct config
+- **Non-migrated packages**: Use `eslint --fix` which runs from the root with the root config
+- **Root files**: Covered by `*.{js,jsx,ts,tsx,json,eslintrc,vue}` pattern
+
+This configuration will be simplified once all packages are migrated to the unified ESLint setup.
+
+### 2. **Batch Packages for Migration**
+- **Batch by directory/type** to keep PRs manageable and reduce risk.
+- **Batch size:** 4–8 packages per PR, grouped by similarity.
+
+### 2. **Migration Steps for Each Package**
+
+For each package in the batch:
+
+1. **Remove old ESLint config and plugin references:**
+   - Delete `.eslintrc`, `.eslintrc.json`, or `.eslintrc.js` in the package.
+   - Remove any references to `@cypress/eslint-plugin-dev` in `package.json` (if present).
+   - **Remove TSLint configs:** Delete `tslint.json` and remove `tslint` dependencies from `package.json`.
+2. **Add a new ESLint config file:**
+   - Create `eslint.config.ts` in the package root:
+     ```ts
+     import baseConfig from '@packages/eslint-config'
+     export default baseConfig
+     ```
+3. **Ensure dependencies are up to date:**
+   - Remove any package-local ESLint plugins now provided by the shared config.
+   - Remove TSLint-related dependencies (the new config includes `@typescript-eslint`).
+   - **Add the shared ESLint config as a dev dependency:**
+     - In each migrated package, add `@packages/eslint-config` to `devDependencies` (use a relative file path if not published to npm).
+   - **Add ESLint as a dev dependency:**
+     - Since `@packages/eslint-config` has ESLint as a peer dependency, add `eslint: "^9.18.0"` to `devDependencies`.
+4. **Run lint and autofix:**
+   - From the package root, run:
+     ```
+     npx eslint . --ext .js,.ts,.tsx,.jsx --fix
+     ```
+   - Manually fix any remaining lint errors.
+5. **Verify TypeScript configuration:**
+   - Ensure the package has a valid `tsconfig.json` that works with the new ESLint config.
+   - Run `npx tsc --noEmit` to check for TypeScript compilation errors.
+   - Verify that the new ESLint config can properly parse TypeScript files in the package.
+6. **Run tests for the package** to ensure nothing broke.
+7. **Commit changes** with a clear message, e.g.:
+   ```
+   chore(npm/grep): migrate to @packages/eslint-config and remove legacy eslint-plugin-dev
+   ```
+
+### 3. **Open a PR for Each Batch**
+- Keep each migration PR focused (one batch per PR).
+- List all affected packages in the PR description.
+- Include a checklist for each package:
+  - [ ] Removed old ESLint config
+  - [ ] Added new config
+  - [ ] Ran lint and fixed errors
+  - [ ] Ran tests
+
+### 4. **Document Issues or Gaps**
+- If you hit any missing rules or plugin gaps, note them for follow-up.
+- If a package needs a custom override, add it in a local `eslint.config.ts` (prefer to upstream to the shared config if possible).
+
+### 5. **Deprecate and Remove Old Plugin**
+- Once all packages are migrated, remove `@cypress/eslint-plugin-dev` from the repo and CI.
+
+### 6. **Simplify Lint-Staged Configuration**
+After all packages are migrated, simplify the lint-staged configuration in root `package.json`:
+
+```json
+{
+  "lint-staged": {
+    "**/*.{js,jsx,ts,tsx,json,eslintrc,vue}": "eslint --fix",
+    "*workflows.yml": "node scripts/format-workflow-file.js"
+  }
+}
+```
+
+### 7. **Update Lerna/Monorepo Config**
+- Ensure all packages reference the new config in their `package.json`/`eslint.config.ts`.
+- Update documentation and developer onboarding guides.
+
+---
+
+## Example: Migrating a Batch
+
+1. **Select batch:** e.g., `npm/grep`, `npm/puppeteer`, `npm/mount-utils`, `npm/cypress-schematic`
+2. **For each package:**
+   - Remove `.eslintrc*` files
+   - Add `eslint.config.ts` as above
+   - Remove local plugin deps
+   - Run lint and fix errors
+   - Run tests
+3. **Commit and open PR**
+
+---
+
+## Troubleshooting Guide
+
+### Common Issues and Solutions
+
+#### 1. **Jiti Version Compatibility Error**
+**Error:** `Error: You are using an outdated version of the 'jiti' library. Please update to the latest version of 'jiti' to ensure compatibility and access to the latest features.`
+
+**Solution:**
+- Add `jiti: "^2.4.2"` to the package's `devDependencies`
+- ESLint 9.x requires jiti >= 2.2.0, but monorepo dependencies might provide older versions
+
+#### 2. **TypeScript Project Service Errors**
+**Error:** `was not found by the project service. Consider either including it in the tsconfig.json or including it in allowDefaultProject`
+
+**Solutions:**
+- **Create/update `tsconfig.json`** that extends the base config:
+  ```json
+  {
+    "extends": "../../packages/ts/tsconfig.json",
+    "compilerOptions": {
+      "esModuleInterop": true,
+      "allowJs": true,
+      "checkJs": false
+    },
+    "include": [
+      "src/**/*",
+      "cypress/**/*",
+      "*.js",
+      "*.ts",
+      "*.jsx",
+      "*.tsx"
+    ],
+    "exclude": ["node_modules", "dist"]
+  }
+  ```
+- **For Cypress packages**, ensure `cypress/tsconfig.json` includes all test files:
+  ```json
+  {
+    "compilerOptions": {
+      "types": ["cypress"]
+    },
+    "include": [
+      "**/*.ts",
+      "**/*.js"
+    ]
+  }
+  ```
+- **Add `allowDefaultProject: true`** to ESLint config for problematic files:
+  ```ts
+  {
+    files: ['**/*.js', '**/*.ts', '**/*.jsx', '**/*.tsx'],
+    languageOptions: {
+      parserOptions: {
+        allowDefaultProject: true,
+      },
+    },
+  }
+  ```
+
+#### 3. **Skip Comment Rule Violations**
+**Error:** `@cypress/dev/skip-comment` rule violations for `it.skip()` tests
+
+**Solution:**
+- Replace `eslint-disable-next-line @cypress/dev/skip-comment` with proper explanatory comments:
+  ```js
+  // NOTE: This test is skipped for demonstration purposes
+  it.skip('first test', () => {})
+  ```
+
+#### 4. **Rule Mismatches in Pre-commit Hook**
+**Error:** ESLint rule violations that don't match the package's ESLint configuration (e.g., `Unexpected console statement` when `no-console` is off in package config)
+
+**Root Cause:** Pre-commit hook runs ESLint from root directory using root-level config, not package-specific config
+
+**Solution:**
+- The root `package.json` now includes explicit lint-staged patterns for each package:
+  ```json
+  "lint-staged": {
+    "npm/grep/**/*.{js,jsx,ts,tsx}": "yarn lint:fix",
+    "*.{js,jsx,ts,tsx,json,eslintrc,vue}": "eslint --fix",
+    "cli/**/*.{js,jsx,ts,tsx,json,eslintrc,vue}": "eslint --fix",
+    "packages/**/*.{js,jsx,ts,tsx,json,eslintrc,vue}": "eslint --fix",
+    // ... explicit patterns for each directory
+  }
+  ```
+- **For migrated packages:** Use `yarn lint:fix` which runs the lerna command to execute ESLint from the package directory
+- **For non-migrated packages:** Use `eslint --fix` which runs from the root with the root config
+- **Note:** This verbose configuration is temporary during migration and will be simplified once all packages are migrated
+
+#### 5. **ESLint Script Changes**
+**Before ESLint 9.x:**
+```json
+"lint": "eslint . --ext .js,.ts"
+```
+
+**After ESLint 9.x:**
+```json
+"lint": "eslint"
+```
+ESLint 9.x auto-detects file extensions, so `--ext` flag is no longer needed.
+
+#### 6. **Package Dependencies**
+**Required additions to `package.json`:**
+```json
+{
+  "devDependencies": {
+    "@packages/eslint-config": "0.0.0-development",
+    "eslint": "^9.18.0",
+    "jiti": "^2.4.2"
+  }
+}
+```
+
+#### 7. **Custom Package Rules**
+If a package needs custom rules, extend the base config:
+```ts
+import baseConfig from '@packages/eslint-config'
+
+export default [
+  ...baseConfig,
+  {
+    files: ['**/*.js', '**/*.ts', '**/*.jsx', '**/*.tsx'],
+    rules: {
+      'no-console': 'off',
+      'no-restricted-syntax': 'off',
+    },
+  },
+  {
+    files: ['cypress/**/*.js', 'cypress/**/*.ts'],
+    languageOptions: {
+      globals: {
+        Cypress: 'readonly',
+        cy: 'readonly',
+      },
+    },
+  },
+]
+```
+
+### Migration Checklist Template
+
+For each package, ensure you've completed:
+
+- [ ] Removed `.eslintrc*` files
+- [ ] Created `eslint.config.ts` with proper configuration
+- [ ] Added required dependencies (`eslint`, `@packages/eslint-config`, `jiti`)
+- [ ] Created/updated `tsconfig.json` that extends base config
+- [ ] Updated ESLint scripts (removed `--ext` flag)
+- [ ] Ran `yarn lint` successfully
+- [ ] Ran tests to ensure nothing broke
+
+---
+
+## Tips
+- Use a tracking issue or project board to coordinate and document progress.
+- If a package is especially noisy, consider splitting it into its own PR.
+- Communicate with the team about the migration timeline and process.
+- **Test the pre-commit hook** before pushing to ensure lint-staged works correctly.
+
+## Recent Updates
+- **Fixed lint-staged configuration** to properly handle migrated vs non-migrated packages
+- **Added explicit directory patterns** to ensure complete coverage during migration period
+
+---
+
+**Happy linting!** 

npm/grep/cypress/e2e/omit-and-skip-spec.js

@@ -3,7 +3,7 @@
 // @ts-check
 describe('Page', () => {
   describe('List', { tags: ['@us1'] }, () => {
-    // eslint-disable-next-line @cypress/dev/skip-comment
+    // NOTE: This test is skipped for demonstration purposes
     it.skip('first test', () => {})
     it('second test', () => {})
     it('third test', () => {})

npm/grep/cypress/e2e/skip-spec.js

@@ -1,10 +1,11 @@
-/* eslint-disable @cypress/dev/skip-comment */
 /// <reference types="cypress" />
 describe('tests that use .skip', () => {
   // use a template literal
   it(`works`, () => {})
 
+  // NOTE: This test is pending for demonstration
   it.skip('is pending', () => {})
 
+  // NOTE: This test is also pending for demonstration
   it.skip('is pending again', () => {})
 })

npm/grep/cypress/tsconfig.json

@@ -1,6 +1,11 @@
 {
   "compilerOptions": {
-    "types": ["cypress"]
+    "types": ["cypress"],
+    "allowJs": true,
+    "checkJs": false
   },
-  "include": ["e2e/**/*.ts"]
+  "include": [
+    "**/*.ts",
+    "**/*.js"
+  ]
 }