fix: only lint when enabled

test/lib/next-test-utils.ts

@@ -18,7 +18,6 @@ import fetch from 'node-fetch'
 import qs from 'querystring'
 import treeKill from 'tree-kill'
 import { once } from 'events'
-import vm from 'vm'
 
 import server from 'next/dist/server/next'
 import _pkg from 'next/package.json'
@@ -192,6 +191,7 @@ export interface NextOptions {
   stderr?: true | 'log'
   stdout?: true | 'log'
   ignoreFail?: boolean
+  lint?: boolean
 
   onStdout?: (data: any) => void
   onStderr?: (data: any) => void
@@ -438,71 +438,13 @@ export function launchApp(
   )
 }
 
-/**
- * Read a JavaScript file and return the exports.
- *
- * @param path The path to the JavaScript file.
- * @returns The exports of the JavaScript file.
- */
-function readJS(path: string) {
-  const data = readFileSync(path, 'utf8')
-  const script = new vm.Script(data, { filename: path })
-  const context = { module: { exports: {} } }
-  script.runInNewContext(context)
-  return context.module.exports
-}
-
-/**
- * Check if the directory provides an ESLint configuration.
- *
- * @param dir The directory to check.
- * @returns Whether the directory provides an ESLint configuration.
- */
-export function shouldDisableLinting(dir: string) {
-  try {
-    // If the project already has a `next.config.js` file that includes an eslint
-    // config, then don't disable linting.
-    if (
-      existsSync(path.join(dir, 'next.config.js')) &&
-      'eslint' in readJS(path.join(dir, 'next.config.js'))
-    ) {
-      return false
-    }
-
-    // If some of these files exist, we should not disable linting.
-    if (
-      ['.eslintrc.json', '.eslintrc.js', '.eslintrc'].some((file) =>
-        existsSync(path.join(dir, file))
-      )
-    ) {
-      return false
-    }
-
-    // If the `eslintConfig` field is present in the `package.json` file, we
-    // should not disable linting.
-    if (
-      existsSync(path.join(dir, 'package.json')) &&
-      readJson(path.join(dir, 'package.json')).eslintConfig
-    ) {
-      return false
-    }
-
-    return true
-  } catch {
-    // An error ocurred while checking the directory, so we should not disable
-    // linting.
-    return false
-  }
-}
-
 export function nextBuild(
   dir: string,
   args: string[] = [],
   opts: NextOptions = {}
 ) {
-  // Disable linting if the directory provides an ESLint configuration. This
-  // prevents the project's eslint configuration from affecting the test.
-  if (shouldDisableLinting(dir)) args.push('--no-lint')
+  // If the build hasn't requested it to be linted explicitly, disable linting.
+  if (!opts.lint) args.push('--no-lint')
 
   return runNextCommand(['build', dir, ...args], opts)
 }