fix(linter): Generator creating .eslintrc.json at the root path even when .eslintrc.js already exist

packages/linter/src/generators/init/init.spec.ts

@@ -1,7 +1,6 @@
+import { Linter } from '../utils/linter';
 import { Tree } from '@nrwl/devkit';
 import { createTreeWithEmptyWorkspace } from '@nrwl/devkit/testing';
-
-import { Linter } from '../utils/linter';
 import { lintInitGenerator } from './init';
 
 describe('@nrwl/linter:init', () => {
@@ -20,6 +19,16 @@ describe('@nrwl/linter:init', () => {
 
         expect(tree.read('.eslintrc.json', 'utf-8')).toMatchSnapshot();
       });
+
+      it('should not generate the global eslint config if it already exist', async () => {
+        tree.write('.eslintrc.js', '{}');
+
+        await lintInitGenerator(tree, {
+          linter: Linter.EsLint,
+        });
+
+        expect(tree.exists('.eslintrc.json')).toBe(false);
+      });
     });
 
     describe('tslint', () => {

packages/linter/src/generators/init/init.ts

@@ -1,10 +1,10 @@
+import type { GeneratorCallback, Tree } from '@nrwl/devkit';
 import {
   addDependenciesToPackageJson,
   removeDependenciesFromPackageJson,
   updateJson,
   writeJson,
 } from '@nrwl/devkit';
-import type { GeneratorCallback, Tree } from '@nrwl/devkit';
 import {
   buildAngularVersion,
   eslintConfigPrettierVersion,
@@ -13,7 +13,9 @@ import {
   tslintVersion,
   typescriptESLintVersion,
 } from '../../utils/versions';
+
 import { Linter } from '../utils/linter';
+import { containsEslint } from '../utils/eslint-file';
 
 export interface LinterInitOptions {
   linter?: Linter;
@@ -165,7 +167,7 @@ function initTsLint(tree: Tree, options: LinterInitOptions): GeneratorCallback {
 }
 
 function initEsLint(tree: Tree, options: LinterInitOptions): GeneratorCallback {
-  if (tree.exists('/.eslintrc.json')) {
+  if (containsEslint(tree)) {
     return () => {};
   }
 

packages/linter/src/generators/lint-project/__snapshots__/lint-project.spec.ts.snap

@@ -1,5 +1,42 @@
 // Jest Snapshot v1, https://goo.gl/fbAQLP
 
+exports[`@nrwl/linter:lint-project --linter eslint should extend to .eslintrc.js when an .eslintrc.js already exist 1`] = `
+"{
+  \\"extends\\": [
+    \\"../../.eslintrc.js\\"
+  ],
+  \\"ignorePatterns\\": [
+    \\"!**/*\\"
+  ],
+  \\"overrides\\": [
+    {
+      \\"files\\": [
+        \\"*.ts\\",
+        \\"*.tsx\\",
+        \\"*.js\\",
+        \\"*.jsx\\"
+      ],
+      \\"rules\\": {}
+    },
+    {
+      \\"files\\": [
+        \\"*.ts\\",
+        \\"*.tsx\\"
+      ],
+      \\"rules\\": {}
+    },
+    {
+      \\"files\\": [
+        \\"*.js\\",
+        \\"*.jsx\\"
+      ],
+      \\"rules\\": {}
+    }
+  ]
+}
+"
+`;
+
 exports[`@nrwl/linter:lint-project --linter eslint should generate a eslint config 1`] = `
 "{
   \\"extends\\": [

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

@@ -1,11 +1,11 @@
 import {
+  Tree,
   addProjectConfiguration,
   readProjectConfiguration,
-  Tree,
 } from '@nrwl/devkit';
-import { createTreeWithEmptyWorkspace } from '@nrwl/devkit/testing';
 
 import { Linter } from '../utils/linter';
+import { createTreeWithEmptyWorkspace } from '@nrwl/devkit/testing';
 import { lintProjectGenerator } from './lint-project';
 
 describe('@nrwl/linter:lint-project', () => {
@@ -63,6 +63,22 @@ describe('@nrwl/linter:lint-project', () => {
           }
         `);
       });
+
+      it('should extend to .eslintrc.js when an .eslintrc.js already exist', async () => {
+        tree.write('.eslintrc.js', '{}');
+
+        await lintProjectGenerator(tree, {
+          ...defaultOptions,
+          linter: Linter.EsLint,
+          eslintFilePatterns: ['**/*.ts'],
+          project: 'test-lib',
+          setParserOptionsProject: false,
+        });
+
+        expect(
+          tree.read('libs/test-lib/.eslintrc.json', 'utf-8')
+        ).toMatchSnapshot();
+      });
     });
 
     describe('tslint', () => {

packages/linter/src/generators/lint-project/lint-project.ts

@@ -6,8 +6,10 @@ import {
   updateProjectConfiguration,
   writeJson,
 } from '@nrwl/devkit';
-import { join } from 'path';
+
 import { Linter } from '../utils/linter';
+import { findEslintFile } from '../utils/eslint-file';
+import { join } from 'path';
 import { lintInitGenerator } from '../init/init';
 
 interface LintProjectOptions {
@@ -40,7 +42,7 @@ function createEsLintConfiguration(
   setParserOptionsProject: boolean
 ) {
   writeJson(tree, join(projectConfig.root, `.eslintrc.json`), {
-    extends: [`${offsetFromRoot(projectConfig.root)}.eslintrc.json`],
+    extends: [`${offsetFromRoot(projectConfig.root)}${findEslintFile(tree)}`],
     // Include project files to be linted since the global one excludes all files.
     ignorePatterns: ['!**/*'],
     overrides: [

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

@@ -0,0 +1,55 @@
+import { containsEslint, findEslintFile } from './eslint-file';
+
+import { Tree } from '@nrwl/devkit';
+import { createTreeWithEmptyWorkspace } from '@nrwl/devkit/testing';
+
+describe('@nrwl/linter:eslint-file', () => {
+  let tree: Tree;
+
+  beforeEach(() => {
+    tree = createTreeWithEmptyWorkspace();
+  });
+
+  describe('containsEslint', () => {
+    it('should return false when calling containsEslint without a eslint config', () => {
+      expect(containsEslint(tree)).toBe(false);
+    });
+
+    it('should return true when calling containsEslint with a .eslintrc.json config', () => {
+      tree.write('.eslintrc.json', '{}');
+      expect(containsEslint(tree)).toBe(true);
+    });
+
+    it('should return true when calling containsEslint with a .eslintrc.js config', () => {
+      tree.write('.eslintrc.js', '{}');
+      expect(containsEslint(tree)).toBe(true);
+    });
+
+    it('should return false when calling containsEslint witn an incorrect eslint file name', () => {
+      tree.write('.eslintrc.yaml', '{}');
+      expect(containsEslint(tree)).toBe(false);
+    });
+  });
+
+  describe('findEslintFile', () => {
+    it('should return default name when calling findEslintFile when no eslint is found', () => {
+      expect(findEslintFile(tree)).toBe('eslintrc.json');
+    });
+
+    it('should return the name of the eslint config when calling findEslintFile', () => {
+      tree.write('.eslintrc.json', '{}');
+      expect(findEslintFile(tree)).toBe('.eslintrc.json');
+    });
+
+    it('should return the name of the eslint config when calling findEslintFile', () => {
+      tree.write('.eslintrc.js', '{}');
+      expect(findEslintFile(tree)).toBe('.eslintrc.js');
+    });
+
+    it('should return default name when calling findEslintFile when no eslint is found', () => {
+      tree.write('.eslintrc.yaml', '{}');
+
+      expect(findEslintFile(tree)).toBe('eslintrc.json');
+    });
+  });
+});

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

@@ -0,0 +1,22 @@
+import type { Tree } from '@nrwl/devkit';
+
+const eslintFileList = ['.eslintrc.json', '.eslintrc.js'];
+
+export function containsEslint(tree: Tree): boolean {
+  for (const file of eslintFileList) {
+    if (tree.exists(file)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+export function findEslintFile(tree: Tree): string {
+  for (const file of eslintFileList) {
+    if (tree.exists(file)) {
+      return file;
+    }
+  }
+  // Default file
+  return 'eslintrc.json';
+}