fix(core): update ESLint config file references from cjs to mjs

closes: #29493, #22576

Author: ndcunningham

e2e/angular/src/misc.test.ts

@@ -39,7 +39,7 @@ describe('Move Angular Project', () => {
     expect(moveOutput).toContain(`CREATE ${newPath}/tsconfig.app.json`);
     expect(moveOutput).toContain(`CREATE ${newPath}/tsconfig.json`);
     expect(moveOutput).toContain(`CREATE ${newPath}/tsconfig.spec.json`);
-    expect(moveOutput).toContain(`CREATE ${newPath}/eslint.config.cjs`);
+    expect(moveOutput).toContain(`CREATE ${newPath}/eslint.config.mjs`);
     expect(moveOutput).toContain(`CREATE ${newPath}/public/favicon.ico`);
     expect(moveOutput).toContain(`CREATE ${newPath}/src/index.html`);
     expect(moveOutput).toContain(`CREATE ${newPath}/src/main.ts`);

e2e/angular/src/projects.test.ts

@@ -164,13 +164,13 @@ describe('Angular Projects', () => {
 
   it('should lint correctly with eslint and handle external HTML files and inline templates', async () => {
     // disable the prefer-standalone rule for app1 which is not standalone
-    let app1EslintConfig = readFile(`${app1}/eslint.config.cjs`);
+    let app1EslintConfig = readFile(`${app1}/eslint.config.mjs`);
     app1EslintConfig = app1EslintConfig.replace(
       `'@angular-eslint/directive-selector': [`,
       `'@angular-eslint/prefer-standalone': 'off',
       '@angular-eslint/directive-selector': [`
     );
-    updateFile(`${app1}/eslint.config.cjs`, app1EslintConfig);
+    updateFile(`${app1}/eslint.config.mjs`, app1EslintConfig);
 
     // check apps and lib pass linting for initial generated code
     runCLI(`run-many --target lint --projects=${app1},${lib1} --parallel`);

e2e/eslint/src/linter-legacy.test.ts

@@ -150,10 +150,10 @@ describe('Linter (legacy)', () => {
         env: { NX_ADD_PLUGINS: 'false' },
       });
       checkFilesExist(
-        'eslint.config.cjs',
-        `apps/${myapp}/eslint.config.cjs`,
-        `libs/${mylib}/eslint.config.cjs`,
-        `libs/${mylib2}/eslint.config.cjs`
+        'eslint.config.mjs',
+        `apps/${myapp}/eslint.config.mjs`,
+        `libs/${mylib}/eslint.config.mjs`,
+        `libs/${mylib2}/eslint.config.mjs`
       );
       checkFilesDoNotExist(
         '.eslintrc.json',
@@ -164,12 +164,12 @@ describe('Linter (legacy)', () => {
 
       // move eslint.config one step up
       // to test the absence of the flat eslint config in the project root folder
-      renameFile(`libs/${mylib2}/eslint.config.cjs`, `libs/eslint.config.cjs`);
+      renameFile(`libs/${mylib2}/eslint.config.mjs`, `libs/eslint.config.mjs`);
       updateFile(
-        `libs/eslint.config.cjs`,
-        readFile(`libs/eslint.config.cjs`).replace(
-          `../../eslint.config.cjs`,
-          `../eslint.config.cjs`
+        `libs/eslint.config.mjs`,
+        readFile(`libs/eslint.config.mjs`).replace(
+          `../../eslint.config.mjs`,
+          `../eslint.config.mjs`
         )
       );
 
@@ -202,9 +202,9 @@ describe('Linter (legacy)', () => {
         env: { NX_ADD_PLUGINS: 'false' },
       });
       checkFilesExist(
-        'eslint.config.cjs',
-        `${mylib}/eslint.config.cjs`,
-        'eslint.base.config.cjs'
+        'eslint.config.mjs',
+        `${mylib}/eslint.config.mjs`,
+        'eslint.base.config.mjs'
       );
       checkFilesDoNotExist(
         '.eslintrc.json',

e2e/eslint/src/linter.test.ts

@@ -615,8 +615,8 @@ describe('Linter', () => {
         runCLI(`generate @nx/js:lib ${jsLib} --linter eslint`);
 
         checkFilesExist(
-          `${reactLib}/eslint.config.cjs`,
-          `${jsLib}/eslint.config.cjs`
+          `${reactLib}/eslint.config.mjs`,
+          `${jsLib}/eslint.config.mjs`
         );
         checkFilesDoNotExist(
           `${reactLib}/.eslintrc.json`,

e2e/nx/src/__snapshots__/extras.test.ts.snap

@@ -26,7 +26,7 @@ exports[`Extra Nx Misc Tests task graph inputs should correctly expand dependent
   ],
   "lib-base-123": [
     "libs/lib-base-123/README.md",
-    "libs/lib-base-123/eslint.config.cjs",
+    "libs/lib-base-123/eslint.config.mjs",
     "libs/lib-base-123/jest.config.ts",
     "libs/lib-base-123/package.json",
     "libs/lib-base-123/project.json",
@@ -39,7 +39,7 @@ exports[`Extra Nx Misc Tests task graph inputs should correctly expand dependent
   ],
   "lib-dependent-123": [
     "libs/lib-dependent-123/README.md",
-    "libs/lib-dependent-123/eslint.config.cjs",
+    "libs/lib-dependent-123/eslint.config.mjs",
     "libs/lib-dependent-123/jest.config.ts",
     "libs/lib-dependent-123/package.json",
     "libs/lib-dependent-123/project.json",

packages/eslint/src/generators/lint-project/lint-project.spec.ts

@@ -56,6 +56,7 @@ describe('@nx/eslint:lint-project', () => {
 
     expect(tree.read('eslint.config.mjs', 'utf-8')).toMatchInlineSnapshot(`
       "import nx from "@nx/eslint-plugin";
+
       export default [
           ...nx.configs["flat/base"],
           ...nx.configs["flat/typescript"],

packages/eslint/src/generators/utils/eslint-file.ts

@@ -149,6 +149,19 @@ function replaceFlatConfigPaths(
       `require('${newPath}')` +
       newConfig.slice(match.index + match[0].length);
   }
+
+  // Handle import statements
+  const importRegex = RegExp(/import\s+.*?\s+from\s+['"](.*)['"]/g);
+  while ((match = importRegex.exec(newConfig)) !== null) {
+    const oldPath = match[1];
+    const newPath = offsetFilePath(sourceRoot, oldPath, offset, tree);
+
+    // Replace the old path with the updated path
+    newConfig =
+      newConfig.slice(0, match.index + match[0].indexOf(oldPath)) +
+      newPath +
+      newConfig.slice(match.index + match[0].indexOf(oldPath) + oldPath.length);
+  }
   // replace projects
   const projectRegex = RegExp(/project:\s?\[?['"](.*)['"]\]?/g);
   while ((match = projectRegex.exec(newConfig)) !== null) {

packages/eslint/src/generators/utils/flat-config/ast-utils.spec.ts

@@ -211,6 +211,7 @@ describe('ast-utils', () => {
       );
       expect(result).toMatchInlineSnapshot(`
         "import baseConfig from "../../eslint.config.mjs";
+
         export default [
             ...baseConfig,
             {
@@ -254,6 +255,7 @@ describe('ast-utils', () => {
       );
       expect(result).toMatchInlineSnapshot(`
         "import baseConfig from "../../eslint.config.mjs";
+
         export default [
             ...config,
             ...baseConfig,

packages/eslint/src/generators/utils/flat-config/ast-utils.ts

@@ -29,7 +29,7 @@ export function removeOverridesFromLintConfig(content: string): string {
   const format = content.includes('export default') ? 'mjs' : 'cjs';
 
   const exportsArray =
-    format === 'mjs' ? findAllBlocks(source) : findModuleExports(source);
+    format === 'mjs' ? findExportDefault(source) : findModuleExports(source);
   if (!exportsArray) {
     return content;
   }
@@ -51,7 +51,7 @@ export function removeOverridesFromLintConfig(content: string): string {
 }
 
 // TODO Change name
-function findAllBlocks(source: ts.SourceFile): ts.NodeArray<ts.Node> {
+function findExportDefault(source: ts.SourceFile): ts.NodeArray<ts.Node> {
   return ts.forEachChild(source, function analyze(node) {
     if (
       ts.isExportAssignment(node) &&
@@ -103,7 +103,7 @@ export function hasOverride(
   );
   const format = content.includes('export default') ? 'mjs' : 'cjs';
   const exportsArray =
-    format === 'mjs' ? findAllBlocks(source) : findModuleExports(source);
+    format === 'mjs' ? findExportDefault(source) : findModuleExports(source);
   if (!exportsArray) {
     return false;
   }
@@ -161,7 +161,7 @@ export function replaceOverride(
   );
   const format = content.includes('export default') ? 'mjs' : 'cjs';
   const exportsArray =
-    format === 'mjs' ? findAllBlocks(source) : findModuleExports(source);
+    format === 'mjs' ? findExportDefault(source) : findModuleExports(source);
   if (!exportsArray) {
     return content;
   }
@@ -683,7 +683,9 @@ function addBlockToFlatConfigExportESM(
 
   const updatedSource = ts.factory.updateSourceFile(source, updatedStatements);
 
-  return printer.printFile(updatedSource);
+  return printer
+    .printFile(updatedSource)
+    .replace(/export default/, '\nexport default');
 }
 
 function addBlockToFlatConfigExportCJS(
@@ -918,7 +920,7 @@ export function removeCompatExtends(
   const changes: StringChange[] = [];
   const format = content.includes('export default') ? 'mjs' : 'cjs';
   const exportsArray =
-    format === 'mjs' ? findAllBlocks(source) : findModuleExports(source);
+    format === 'mjs' ? findExportDefault(source) : findModuleExports(source);
 
   if (!exportsArray) {
     return content;
@@ -989,7 +991,7 @@ export function removePredefinedConfigs(
   const changes: StringChange[] = [];
   let removeImport = true;
   const exportsArray =
-    format === 'mjs' ? findAllBlocks(source) : findModuleExports(source);
+    format === 'mjs' ? findExportDefault(source) : findModuleExports(source);
   if (!exportsArray) {
     return content;
   }

packages/next/src/generators/application/application.spec.ts

@@ -644,6 +644,7 @@ describe('app', () => {
             baseDirectory: dirname(fileURLToPath(import.meta.url)),
             recommendedConfig: js.configs.recommended,
           });
+
           export default [
             ...compat.extends('next', 'next/core-web-vitals'),
             ...baseConfig,

packages/nuxt/src/generators/application/__snapshots__/application.spec.ts.snap

@@ -76,6 +76,7 @@ const compat = new FlatCompat({
   baseDirectory: dirname(fileURLToPath(import.meta.url)),
   recommendedConfig: js.configs.recommended,
 });
+
 export default [
   ...baseConfig,
   {
@@ -469,6 +470,7 @@ const compat = new FlatCompat({
   baseDirectory: dirname(fileURLToPath(import.meta.url)),
   recommendedConfig: js.configs.recommended,
 });
+
 export default [
   ...baseConfig,
   {

packages/vue/src/generators/library/__snapshots__/library.spec.ts.snap

@@ -305,6 +305,7 @@ module.exports = [
 exports[`library should support eslint flat config ESM 1`] = `
 "import vue from 'eslint-plugin-vue';
 import baseConfig from '../eslint.config.mjs';
+
 export default [
   ...baseConfig,
   ...vue.configs['flat/recommended'],

packages/workspace/src/generators/move/lib/update-eslint-config.ts

@@ -16,9 +16,11 @@ export function updateEslintConfig(
     !tree.exists('.eslintrc.json') &&
     !tree.exists('eslint.config.js') &&
     !tree.exists('eslint.config.cjs') &&
+    !tree.exists('eslint.config.mjs') &&
     !tree.exists('.eslintrc.base.json') &&
     !tree.exists('eslint.base.config.js') &&
-    !tree.exists('eslint.base.config.cjs')
+    !tree.exists('eslint.base.config.cjs') &&
+    !tree.exists('eslint.base.config.mjs')
   ) {
     return;
   }