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How to use createResolveOptions method in Jest

Best JavaScript code snippet using jest

index.js

Source:index.js

1/* eslint-disable jsdoc/no-undefined-types */2import _fs, { promises as fs } from 'fs';3import path from 'path';4import { promisify } from 'util';5import enhancedResolve from 'enhanced-resolve';6import postcss from 'postcss';7import _import from 'postcss-import';8// @ts-ignore9import _importSync from 'postcss-import-sync2';10// @ts-ignore11import allSettled from '@ungap/promise-all-settled';12/**13 * @typedef {import('sass').ImporterReturnType} sass.ImporterReturnType14 * @typedef {import('sass').Options} sass.Options15 */16/**17 * @typedef {(18 *   this: { fromImport: boolean, options: { includePaths: string } },19 *   url: string,20 *   prev: string,21 *   done?: (data: sass.ImporterReturnType) => void,22 *  ) => sass.ImporterReturnType | void} Importer23 */24/**25 * @typedef {({status: 'fulfilled', value: any, reason?: undefined}|{status: 'rejected', reason: unknown, value?: undefined})} SettledResult26 */27/**28 * @param   {Function[]}      tasks29 *30 * @returns {SettledResult[]}31 */32function allSettledSync(tasks) {33	return tasks.map((task) => {34		try {35			return { status: 'fulfilled', value: task() };36		} catch (/** @type {any} */ error_) {37			/** @type {Error} */38			const error = error_;39			return { status: 'rejected', reason: error };40		}41	});42}43function createResolvers(sync = false) {44	const { extensions, conditionNames, mainFiles, ...resolveOptions } = {45		extensions: ['.css'],46		conditionNames: ['style', 'browser', 'import', 'require', 'node'],47		mainFields: ['style', 'browser', 'module', 'main'],48		mainFiles: ['index'],49		modules: ['node_modules']50	};51	const createResolveOptions = {52		extensions: ['.scss', ...extensions],53		conditionNames: ['sass', ...conditionNames],54		mainFiles: ['_index', ...mainFiles],55		...resolveOptions56	};57	const createGenericResolveOptions = {58		extensions,59		conditionNames,60		mainFiles,61		...resolveOptions62	};63	if (sync) {64		const resolve = enhancedResolve.create.sync(createResolveOptions);65		const genericResolve = enhancedResolve.create.sync(66			createGenericResolveOptions67		);68		const cssProcessor = postcss([69			_importSync({70				resolve: (71					/** @type {string} */ id,72					/** @type {string} */ basedir73				) => genericResolve(basedir, id)74			})75		]);76		return {77			resolve,78			genericResolve,79			cssProcessor80		};81	}82	/** @type {(basedir: string, id: string) => Promise<string>} */83	const resolve = promisify(enhancedResolve.create(createResolveOptions));84	/** @type {(basedir: string, id: string) => Promise<string>} */85	const genericResolve = promisify(86		enhancedResolve.create(createGenericResolveOptions)87	);88	// @ts-ignore89	const cssProcessor = postcss([90		_import({91			resolve: (id, basedir) => genericResolve(basedir, id)92		})93	]);94	return {95		resolve,96		cssProcessor97	};98}99/**100 * Sass importer to import Sass modules using (enhanced) Node resolve.101 */102function api() {103	const { resolve, cssProcessor } = createResolvers();104	const { resolve: resolveSync, cssProcessor: cssProcessorSync } =105		createResolvers(true);106	/**107	 * @param {string} includePaths108	 */109	function asyncFunction(includePaths) {110		/** @type {Importer} */111		return async function (url, previous, _done) {112			const done = typeof _done !== 'undefined' ? _done : () => {};113			/** @type {string?} */114			let filePath = null;115			try {116				if (previous === 'stdin') {117					/** @type {SettledResult[]} */118					const filePaths = await allSettled.call(119						Promise,120						includePaths121							.split(':')122							.map((includePath) =>123								path.isAbsolute(includePath)124									? includePath125									: path.resolve(process.cwd(), includePath)126							)127							.map((includePath) => resolve(includePath, url))128					);129					const foundFilePath = filePaths.find(130						({ status }) => status === 'fulfilled'131					);132					filePath =133						typeof foundFilePath !== 'undefined'134							? foundFilePath.value135							: null;136				} else {137					const foundFilePath = await resolve(138						path.dirname(previous),139						url140					);141					filePath = foundFilePath || null;142				}143			} catch (error) {144				/* istanbul ignore next */145				filePath = null;146			}147			/* istanbul ignore next */148			if (filePath === null) {149				done(null);150				return;151			}152			if (path.extname(filePath) !== '.css') {153				done({ file: filePath });154				return;155			}156			const css = await fs.readFile(filePath, 'utf8');157			if (!css.includes('@import')) {158				done({ file: filePath });159				return;160			}161			try {162				const result = await cssProcessor.process(css, {163					from: filePath164				});165				done({ contents: result.css });166			} catch (/** @type {any} */ error_) {167				/** @type {Error} */168				const error = error_;169				/* istanbul ignore next */170				done(error);171			}172		};173	}174	/**175	 * @param {string} includePaths176	 */177	function syncFunction(includePaths) {178		/** @type {Importer} */179		return function (url, previous) {180			/** @type {string?} */181			let filePath = null;182			try {183				if (previous === 'stdin') {184					const filePaths = allSettledSync.call(185						null,186						includePaths187							.split(':')188							.map((includePath) =>189								path.isAbsolute(includePath)190									? includePath191									: path.resolve(process.cwd(), includePath)192							)193							.map(194								(includePath) => () =>195									resolveSync(includePath, url)196							)197					);198					const foundFilePath = filePaths.find(199						({ status }) => status === 'fulfilled'200					);201					filePath =202						typeof foundFilePath !== 'undefined'203							? foundFilePath.value204							: null;205				} else {206					const foundFilePath = resolveSync(207						path.dirname(previous),208						url209					);210					// @ts-ignore211					filePath = foundFilePath || null;212				}213			} catch (error) {214				/* istanbul ignore next */215				filePath = null;216			}217			/* istanbul ignore next */218			if (filePath === null) {219				return null;220			}221			if (path.extname(filePath) !== '.css') {222				return { file: filePath };223			}224			const css = _fs.readFileSync(filePath, 'utf8');225			if (!css.includes('@import')) {226				return { file: filePath };227			}228			try {229				const result = cssProcessorSync.process(css, {230					from: filePath231				});232				return { contents: result.css };233			} catch (/** @type {any} */ error_) {234				/** @type {Error} */235				const error = error_;236				/* istanbul ignore next */237				return error;238			}239		};240	}241	/**242	 * @type {Importer}243	 */244	function main(...arguments_) {245		const { includePaths } = this.options;246		const [url, previous, done] = arguments_;247		asyncFunction(includePaths).apply(this, [url, previous, done]);248	}249	/**250	 * @type {Importer}251	 */252	function sync(...arguments_) {253		const { includePaths } = this.options;254		const [url, previous] = arguments_;255		return syncFunction(includePaths).apply(this, [url, previous]);256	}257	/**258	 * Sass importer to import Sass modules using (enhanced) Node resolve. Synchronous version.259	 */260	main.sync = sync;261	return main;262}...

Jest Testing Tutorial

LambdaTest’s Jest Testing Tutorial covers step-by-step guides around Jest with code examples to help you be proficient with the Jest framework. The Jest tutorial has chapters to help you learn right from the basics of Jest framework to code-based tutorials around testing react apps with Jest, perform snapshot testing, import ES modules and more.

Chapters

What is Jest Framework
Advantages of Jest - Jest has 3,898,000 GitHub repositories, as mentioned on its official website. Learn what makes Jest special and why Jest has gained popularity among the testing and developer community.
Jest Installation - All the prerequisites and set up steps needed to help you start Jest automation testing.
Using Jest with NodeJS Project - Learn how to leverage Jest framework to automate testing using a NodeJS Project.
Writing First Test for Jest Framework - Get started with code-based tutorial to help you write and execute your first Jest framework testing script.
Jest Vocabulary - Learn the industry renowned and official jargons of the Jest framework by digging deep into the Jest vocabulary.
Unit Testing with Jest - Step-by-step tutorial to help you execute unit testing with Jest framework.
Jest Basics - Learn about the most pivotal and basic features which makes Jest special.
Jest Parameterized Tests - Avoid code duplication and fasten automation testing with Jest using parameterized tests. Parameterization allows you to trigger the same test scenario over different test configurations by incorporating parameters.
Jest Matchers - Enforce assertions better with the help of matchers. Matchers help you compare the actual output with the expected one. Here is an example to see if the object is acquired from the correct class or not. -

|it('check_object_of_Car', () => { expect(newCar()).toBeInstanceOf(Car); });| | :- |

Jest Hooks: Setup and Teardown - Learn how to set up conditions which needs to be followed by the test execution and incorporate a tear down function to free resources after the execution is complete.
Jest Code Coverage - Unsure there is no code left unchecked in your application. Jest gives a specific flag called --coverage to help you generate code coverage.
HTML Report Generation - Learn how to create a comprehensive HTML report based on your Jest test execution.
Testing React app using Jest Framework - Learn how to test your react web-application with Jest framework in this detailed Jest tutorial.
Test using LambdaTest cloud Selenium Grid - Run your Jest testing script over LambdaTest cloud-based platform and leverage parallel testing to help trim down your test execution time.
Snapshot Testing for React Front Ends - Capture screenshots of your react based web-application and compare them automatically for visual anomalies with the help of Jest tutorial.
Bonus: Import ES modules with Jest - ES modules are also known as ECMAScript modules. Learn how to best use them by importing in your Jest testing scripts.
Jest vs Mocha vs Jasmine - Learn the key differences between the most popular JavaScript-based testing frameworks i.e. Jest, Mocha, and Jasmine.
Jest FAQs(Frequently Asked Questions) - Explore the most commonly asked questions around Jest framework, with their answers.