Use extends in overrides

Now eslint/eslint#8813 is fixed this leads to much less object merging

rules/auto.js

@@ -31,34 +31,25 @@ const getConfig = ({ prettier = true, esModules = false }) => {
 		config.settings = { react: { pragma: 'h' } };
 	}
 
-	const getJestConfig = () => {
-		// Can't extend in overrides: https://github.com/eslint/eslint/issues/8813
-		const jestConfig = require('./jest');
-		return Object.assign({}, jestConfig, {
-			files: [
-				'**/__tests__/**/*.js',
-				'**/__mocks__/**/*.js',
-				'test/**/*.js',
-				'test/**/*.jsx',
-			],
-		});
-	};
+	const getJestConfig = () => ({
+		files: [
+			'**/__tests__/**/*.js',
+			'**/__mocks__/**/*.js',
+			'test/**/*.js',
+			'test/**/*.jsx',
+		],
+		extends: path.join(__dirname, './jest.js'),
+	});
 
-	const getMochaConfig = () => {
-		// Can't extend in overrides: https://github.com/eslint/eslint/issues/8813
-		const mochaConfig = require('../mocha');
-		return Object.assign({}, mochaConfig, {
-			files: ['**/*.test.js', '**/*.spec.js'],
-		});
-	};
+	const getMochaConfig = () => ({
+		files: ['**/*.test.js', '**/*.spec.js'],
+		extends: path.join(__dirname, './mocha.js'),
+	});
 
-	const getCypressConfig = () => {
-		// Can't extend in overrides: https://github.com/eslint/eslint/issues/8813
-		const cypressConfig = require('./cypress');
-		return Object.assign({}, cypressConfig, {
-			files: ['cypress/**/*.js'],
-		});
-	};
+	const getCypressConfig = () => ({
+		files: ['cypress/**/*.js'],
+		extends: path.join(__dirname, './cypress.js'),
+	});
 
 	config.extends = usingJsx
 		? [path.join(__dirname, './react.js')]

rules/cypress.js

@@ -1,11 +1,11 @@
 'use strict';
 
-const cypressConfig = require('eslint-plugin-cypress').configs.recommended;
-const mochaConfig = require('./mocha');
+const path = require('path');
 
-const mergedConfig = Object.assign({}, mochaConfig, {
+const mergedConfig = {
+	extends: ['plugin:cypress/recommended', path.join(__dirname, './mocha.js')],
 	// Can't extend in overrides: https://github.com/eslint/eslint/issues/8813
-	rules: Object.assign({}, mochaConfig.rules, cypressConfig.rules, {
+	rules: {
 		// allow top-level hooks in cypress setup files
 		'mocha/no-top-level-hooks': 'off',
 		// allow dev-deps in cypress test directories
@@ -16,8 +16,7 @@ const mergedConfig = Object.assign({}, mochaConfig, {
 				optionalDependencies: false,
 			},
 		],
-	}),
-	plugins: [...(mochaConfig.plugins || []), ...(cypressConfig.plugins || [])],
-});
+	},
+};
 
 module.exports = mergedConfig;

rules/jest.js

@@ -1,32 +1,27 @@
 'use strict';
 
-const jestConfig = require('eslint-plugin-jest').configs.recommended;
 const { usingJsx } = require('../lib/feature-detect');
 
-// Can't extend in overrides: https://github.com/eslint/eslint/issues/8813
-// the default jest/globals with jest/recommended doesn't work with eslint@5.x.x
-// https://github.com/jest-community/eslint-plugin-jest/issues/128
-jestConfig.env = {
-	jest: true,
+const config = {
+	extends: ['plugin:jest/recommended'],
+	rules: {
+		// This disallows .skip, which is auseful tool for writing skelton tests
+		// prior to full implementation. no-focused-tests is still enabled, which
+		// catches .only - that's the killer
+		'jest/no-disabled-tests': [0, { extensions: ['.js', '.jsx'] }],
+
+		// Disable as it's frequently necessary to do inline requires
+		// when working with jest mocks
+		'global-require': 'off',
+	},
 };
+
 if (usingJsx) {
 	// allow test files to contain jsx but still keep the .js extension
-	jestConfig.rules['react/jsx-filename-extension'] = [
+	config.rules['react/jsx-filename-extension'] = [
 		'error',
 		{ extensions: ['.js', '.jsx'] },
 	];
 }
 
-// This disallows .skip, which is auseful tool for writing skelton tests
-// prior to full implementation. no-focused-tests is still enabled, which
-// catches .only - that's the killer
-jestConfig.rules['jest/no-disabled-tests'] = [
-	0,
-	{ extensions: ['.js', '.jsx'] },
-];
-
-// Disable as it's frequently necessary to do inline requires
-// when working with jest mocks
-jestConfig.rules['global-require'] = 'off';
-
-module.exports = jestConfig;
+module.exports = config;