ESLint 9, flat config migration (#1537)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Aaron Moat <[email protected]>
Co-authored-by: skuba <[email protected]>
Co-authored-by: Sam Chung <[email protected]>

.changeset/big-weeks-enjoy.md

@@ -0,0 +1,18 @@
+---
+'skuba': major
+---
+
+lint: Migrate to ESLint 9 and `@typescript-eslint` 8.
+
+These changes may affect your project setup if customising your ESLint configuration. See the individual migration guides:
+
+- https://eslint.org/docs/latest/use/migrate-to-9.0.0
+- https://typescript-eslint.io/blog/announcing-typescript-eslint-v8
+
+In addition, through these major upgrades, some lint rules have changed or have been renamed. You will likely need adjust your code after running ESLint.
+
+Furthermore, `eslint-plugin-import` has been replaced with `eslint-plugin-import-x`. To migrate, any references to `eslint-plugin-import` should be replaced with `eslint-plugin-import-x`, and `import/` rules with `import-x/`.
+
+As part of this migration, skuba has migrated to using Flat ESLint configuration. Read the migration: https://eslint.org/docs/latest/use/configure/migration-guide.
+
+`skuba format` will attempt to migrate to flat configuration for you, where `.eslintignore` and `.eslintrc` are replaced by `eslint.config.js`.

.changeset/changelog.js

@@ -67,16 +67,17 @@ const gitHubChangelogFunctions = {
 
     const replacedChangelog = changeset.summary
       .replace(/^\s*(?:pr|pull|pull\s+request):\s*#?(\d+)/im, (_, pr) => {
-        let num = Number(pr);
-        if (!isNaN(num)) prFromSummary = num;
+        const num = Number(pr);
+        if (!isNaN(num)) {
+          prFromSummary = num;
+        }
         return '';
       })
       .replace(/^\s*commit:\s*([^\s]+)/im, (_, commit) => {
         commitFromSummary = commit;
         return '';
       })
-      .replace(/^\s*(?:author|user):\s*@?([^\s]+)/gim, (_, user) => {
-        usersFromSummary.push(user);
+      .replace(/^\s*(?:author|user):\s*@?([^\s]+)/gim, () => {
         return '';
       })
       .trim();
@@ -87,6 +88,7 @@ const gitHubChangelogFunctions = {
 
     const links = await (async () => {
       if (prFromSummary !== undefined) {
+        // eslint-disable-next-line no-shadow
         let { links } = await getInfoFromPullRequest({
           repo: options.repo,
           pull: prFromSummary,
@@ -101,7 +103,8 @@ const gitHubChangelogFunctions = {
       }
       const commitToFetchFrom = commitFromSummary || changeset.commit;
       if (commitToFetchFrom) {
-        let { links } = await getInfo({
+        // eslint-disable-next-line no-shadow
+        const { links } = await getInfo({
           repo: options.repo,
           commit: commitToFetchFrom,
         });
@@ -128,6 +131,7 @@ const gitHubChangelogFunctions = {
 if (process.env.GITHUB_TOKEN) {
   module.exports = gitHubChangelogFunctions;
 } else {
+  // eslint-disable-next-line no-console
   console.warn(
     `Defaulting to Git-based versioning.
 Enable GitHub-based versioning by setting the GITHUB_TOKEN environment variable.

.changeset/inject.js

@@ -1,4 +1,5 @@
 // Hack to add a preamble from .changeset/.PREAMBLE.md to the CHANGELOG.md for a given release
+/* eslint-disable no-sync */
 
 const fs = require('fs');
 

.changeset/rich-chairs-wink.md

@@ -0,0 +1,20 @@
+---
+'skuba': minor
+---
+
+lint: Replace `.buildkite/` files with duplicated YAML merge keys, for example:
+
+```yaml
+# Before
+- <<: *deploy
+  <<: *docker
+  label: stuff
+
+# After
+- <<: [*deploy, *docker]
+  label: stuff
+```
+
+This should have no functional change, and is to support standardised YAML parsing across different tools, including the latest ESLint upgrades.
+
+This migration will not be capture all cases of this (e.g. if there are keys between the merge keys). If you have other cases, update them following the example above.

.changeset/thick-taxis-vanish.md

@@ -0,0 +1,16 @@
+---
+'eslint-config-skuba': major
+---
+
+Migrate to ESLint 9, `@typescript-eslint` 8, `eslint-config-seek` 14.
+
+These changes may affect your project setup if customising your ESLint configuration. See the individual migration guides:
+
+- https://eslint.org/docs/latest/use/migrate-to-9.0.0
+- https://typescript-eslint.io/blog/announcing-typescript-eslint-v8
+
+Through these major upgrades, some lint rules have changed or have been renamed. You will likely need to adjust your code after running ESLint.
+
+As part of this migration, this project has migrated to Flat ESLint configuration. Read the migration: https://eslint.org/docs/latest/use/configure/migration-guide.
+
+Furthermore, `eslint-plugin-import` has been replaced with `eslint-plugin-import-x`. To migrate, any references to `eslint-plugin-import` should be replaced with `eslint-plugin-import-x`, and `import/` rules with `import-x/`.

config/eslint.js

@@ -1,3 +1 @@
-module.exports = {
-  extends: ['skuba'],
-};
+module.exports = require('eslint-config-skuba');

docs/cli/init.md

@@ -158,13 +158,12 @@ Familiarise yourself with the directory structure that **skuba** has created:
     ├── app.test.ts
     ├── app.ts
 ├── .dockerignore
-├── .eslintignore
-├── .eslintrc.js
 ├── .gitignore
 ├── .nvmrc
 ├── .prettierignore
 ├── .prettierrc.js
 ├── Dockerfile
+├── eslint.config.js
 ├── README.md
 ├── docker-compose.yml
 ├── jest.config.js

docs/deep-dives/eslint.md

@@ -24,16 +24,17 @@ Please contribute to the [eslint-config-seek] preset if you feel something is mi
 It may worthwhile starting with a discussion in [#typescriptification] to garner feedback.
 
 If you wish to enforce additional rules within a given codebase or team,
-you can [extend] your `.eslintrc.js`:
+you can [extend] your `eslint.config.js`:
 
 ```javascript
-module.exports = {
-  extends: ['skuba'],
-  rules: {
-    // https://eslint.org/docs/rules/complexity
-    complexity: ['error', { max: 3 }],
+module.exports = [
+  ...require('eslint-config-skuba'),
+  {
+    rules: {
+      // Your custom rules here
+    },
   },
-};
+];
 ```
 
 Let's check that our new rule has taken effect.

eslint.config.js

@@ -0,0 +1,56 @@
+const tsParser = require('@typescript-eslint/parser');
+
+const skuba = require('eslint-config-skuba');
+
+module.exports = [
+  {
+    ignores: [
+      'integration/base/',
+      'integration/format/',
+      'template/',
+      'packages/**/*/lib*/',
+    ],
+  },
+  ...skuba,
+  {
+    rules: {
+      'no-process-exit': 'off',
+    },
+  },
+  {
+    files: ['integration/**/*.{ts,cts,mts,tsx}'],
+
+    languageOptions: {
+      parser: tsParser,
+      ecmaVersion: 5,
+      sourceType: 'script',
+
+      parserOptions: {
+        allowAutomaticSingleRunInference: false,
+      },
+    },
+  },
+  {
+    files: ['src/**/*.{ts,cts,mts,tsx}'],
+
+    rules: {
+      'no-restricted-imports': [
+        'error',
+        {
+          paths: [
+            {
+              name: 'fs',
+              message:
+                'Prefer fs-extra as it implements graceful-fs behaviour.',
+            },
+            {
+              name: 'fs/promises',
+              message:
+                'Prefer fs-extra as it implements graceful-fs behaviour.',
+            },
+          ],
+        },
+      ],
+    },
+  },
+];

package.json

@@ -70,6 +70,7 @@
   },
   "dependencies": {
     "@esbuild-plugins/tsconfig-paths": "^0.1.0",
+    "@eslint/migrate-config": "^1.2.0",
     "@jest/types": "^29.0.0",
     "@octokit/graphql": "^8.0.0",
     "@octokit/graphql-schema": "^15.3.0",
@@ -83,7 +84,7 @@
     "ejs": "^3.1.6",
     "enquirer": "^2.3.6",
     "esbuild": "~0.24.0",
-    "eslint": "^8.56.0",
+    "eslint": "^9.11.1",
     "eslint-config-skuba": "workspace:*",
     "execa": "^5.0.0",
     "fast-glob": "^3.3.2",

packages/eslint-config-skuba/eslint.config.js

@@ -0,0 +1 @@
+module.exports = require('.');