Best JavaScript code snippet using jest
config.js
Source: config.js
...11 presets.splice(index, 1);12 }13}14// Tries to load a .babelrc and returns the parsed object if successful15function loadBabelConfig(babelConfigPath) {16 let config;17 if (fs.existsSync(babelConfigPath)) {18 const content = fs.readFileSync(babelConfigPath, 'utf-8');19 try {20 config = JSON5.parse(content);21 config.babelrc = false;22 } catch (e) {23 logger.error(`=> Error parsing .babelrc file: ${e.message}`);24 throw e;25 }26 }27 if (!config) return null;28 // Remove react-hmre preset.29 // It causes issues with react-storybook.30 // We don't really need it.31 // Earlier, we fix this by runnign storybook in the production mode.32 // But, that hide some useful debug messages.33 if (config.presets) {34 removeReactHmre(config.presets);35 }36 if (config.env && config.env.development && config.env.development.presets) {37 removeReactHmre(config.env.development.presets);38 }39 return config;40}41// `baseConfig` is a webpack configuration bundled with storybook.42// Storybook will look in the `configDir` directory43// (inside working directory) if a config path is not provided.44export default function(configType, baseConfig, projectDir, configDir) {45 const config = baseConfig;46 // Search for a .babelrc in project directory, config directory, and storybook47 // module directory. If found, use that to extend webpack configurations.48 const babelConfigInConfig = loadBabelConfig(path.resolve(configDir, '.babelrc'));49 const babelConfigInProject = loadBabelConfig(path.resolve(projectDir, '.babelrc'));50 const babelConfigInModule = loadBabelConfig('.babelrc');51 let babelConfig = null;52 let babelConfigDir = '';53 if (babelConfigInConfig) {54 logger.info('=> Loading custom .babelrc from config directory.');55 babelConfig = babelConfigInConfig;56 babelConfigDir = configDir;57 } else if (babelConfigInProject) {58 logger.info('=> Loading custom .babelrc from project directory.');59 babelConfig = babelConfigInProject;60 babelConfigDir = projectDir;61 } else {62 babelConfig = babelConfigInModule;63 }64 if (babelConfig) {...
make-cache.js
Source: make-cache.js
...71 }72 }73 return configPath74 }75 function loadBabelConfig(editor) {76 if (!configCache.has(editor)) {77 let babelConfig: ?Object = undefined78 const configPath = findConfigFile(editor)79 if (configPath != null) {80 debug("loadBabelConfig", configPath)81 try {82 if (path.extname(configPath) === ".js") {83 const dontCache = {}84 const requireIfTrusted = makeRequire(trusted => {85 if (trusted === false) {86 return undefined87 }88 if (trusted === true) {89 data.delete(editor)90 configCache.delete(editor)91 }92 return dontCache93 })94 // $FlowExpectError95 const cfg = requireIfTrusted(configPath)96 debug("cfg", cfg)97 babelConfig = typeof cfg === "function" ? cfg() : cfg98 if (babelConfig === dontCache) {99 return undefined100 }101 } else {102 babelConfig = JSON.parse(String(fs.readFileSync(configPath)))103 }104 if (babelConfig) {105 babelConfig.cwd = babelConfig.cwd || path.dirname(configPath)106 const babel = require("@babel/core")107 babelConfig = babel.loadOptions(babelConfig)108 }109 } catch (e) {110 debug("loadBabelConfig error", e)111 }112 debug("babel config", babelConfig)113 }114 configCache.set(editor, babelConfig)115 }116 return configCache.get(editor)117 }118 function watchEditor(editor) {119 if (!editors.has(editor)) {120 editors.set(editor, null)121 subscriptions.add(122 editor.onDidStopChanging(() => {123 data.delete(editor)124 }),125 )126 }127 }128 return {129 get(editor: TextEditor): Info {130 watchEditor(editor)131 if (!data.has(editor)) {132 data.set(editor, parseCode(editor.getText(), loadBabelConfig(editor)))133 }134 // $FlowExpectError - Flow thinks it might return null here135 return data.get(editor)136 },137 }...
index.js
Source: index.js
...44 filename: Path,45 configString: string,46 {config, instrument, rootDir}: {config: ProjectConfig} & CacheKeyOptions,47 ): string {48 const babelOptions = loadBabelConfig(config.cwd, filename);49 const configPath = [50 babelOptions.config || '',51 babelOptions.babelrc || '',52 ];53 return crypto54 .createHash('md5')55 .update(THIS_FILE)56 .update('\0', 'utf8')57 .update(JSON.stringify(babelOptions.options))58 .update('\0', 'utf8')59 .update(fileData)60 .update('\0', 'utf8')61 .update(path.relative(rootDir, filename))62 .update('\0', 'utf8')63 .update(configString)64 .update('\0', 'utf8')65 .update(configPath.join(''))66 .update('\0', 'utf8')67 .update(instrument ? 'instrument' : '')68 .update('\0', 'utf8')69 .update(process.env.NODE_ENV || '')70 .update('\0', 'utf8')71 .update(process.env.BABEL_ENV || '')72 .digest('hex');73 },74 process(75 src: string,76 filename: Path,77 config: ProjectConfig,78 transformOptions?: TransformOptions,79 ): string | TransformedSource {80 const babelOptions = {...loadBabelConfig(config.cwd, filename).options};81 if (transformOptions && transformOptions.instrument) {82 babelOptions.auxiliaryCommentBefore = ' istanbul ignore next ';83 // Copied from jest-runtime transform.js84 babelOptions.plugins = babelOptions.plugins.concat([85 [86 babelIstanbulPlugin,87 {88 // files outside `cwd` will not be instrumented89 cwd: config.rootDir,90 exclude: [],91 },92 ],93 ]);94 }...
babel-jest.js
Source: babel-jest.js
...33 filename,34 configString,35 { config, instrument, rootDir }36 ) {37 const babelOptions = loadBabelConfig(38 JSON.parse(configString).cwd,39 filename40 );41 const configPath = [42 babelOptions.config || '',43 babelOptions.babelrc || ''44 ];45 return crypto46 .createHash('md5')47 .update(THIS_FILE)48 .update('\0', 'utf8')49 .update(JSON.stringify(babelOptions.options))50 .update('\0', 'utf8')51 .update(fileData)52 .update('\0', 'utf8')53 .update(path.relative(rootDir, filename))54 .update('\0', 'utf8')55 .update(configString)56 .update('\0', 'utf8')57 .update(configPath.join(''))58 .update('\0', 'utf8')59 .update(instrument ? 'instrument' : '')60 .update('\0', 'utf8')61 .update(process.env.NODE_ENV || '')62 .update('\0', 'utf8')63 .update(process.env.BABEL_ENV || '')64 .digest('hex');65 },66 process(src, filename, config, transformOptions) {67 const babelOptions = { ...loadBabelConfig(config.cwd, filename).options };68 if (transformOptions && transformOptions.instrument) {69 babelOptions.auxiliaryCommentBefore = ' istanbul ignore next ';70 // Copied from jest-runtime transform.js71 babelOptions.plugins = babelOptions.plugins.concat([72 [73 babelIstanbulPlugin,74 {75 // files outside `cwd` will not be instrumented76 cwd: config.rootDir,77 exclude: []78 }79 ]80 ]);81 }...
babel_config.test.js
Source: babel_config.test.js
...26 ]27 }`,28 },29 });30 const config = loadBabelConfig('.foo');31 expect(config).toEqual({32 babelrc: false,33 plugins: [34 'foo-plugin',35 [36 babelPluginReactDocgenPath,37 {38 DOC_GEN_COLLECTION_NAME: 'STORYBOOK_REACT_CLASSES',39 },40 ],41 ],42 presets: ['env', 'foo-preset'],43 });44 });45 it('should return the config with the extra plugins when `plugins` is not an array.', () => {46 setup({47 files: {48 '.babelrc': `{49 "presets": [50 "env",51 "foo-preset"52 ],53 "plugins": "bar-plugin"54 }`,55 },56 });57 const config = loadBabelConfig('.bar');58 expect(config).toEqual({59 babelrc: false,60 plugins: [61 'bar-plugin',62 [63 babelPluginReactDocgenPath,64 {65 DOC_GEN_COLLECTION_NAME: 'STORYBOOK_REACT_CLASSES',66 },67 ],68 ],69 presets: ['env', 'foo-preset'],70 });71 });72 it('should return the config only with the extra plugins when `plugins` is not present.', () => {73 // Mock a `.babelrc` config file with no plugins key.74 setup({75 files: {76 '.babelrc': `{77 "presets": [78 "env",79 "foo-preset"80 ]81 }`,82 },83 });84 const config = loadBabelConfig('.biz');85 expect(config).toEqual({86 babelrc: false,87 plugins: [88 [89 babelPluginReactDocgenPath,90 {91 DOC_GEN_COLLECTION_NAME: 'STORYBOOK_REACT_CLASSES',92 },93 ],94 ],95 presets: ['env', 'foo-preset'],96 });97 });98});
jest.config.js
Source: jest.config.js
1const { createConfigItem } = require('@babel/core');2const { loadBabelConfig, loadCoreConfig, loadCoreConfigFiles } = require('wc-bundler');3const babel = loadBabelConfig(loadCoreConfig(loadCoreConfigFiles(undefined)).babel, {4 env: { targets: { node: '12' } },5 typescript: true,6});7makeBabelPluginConfigSerializable(babel.plugins);8makeBabelPluginConfigSerializable(babel.presets);9/** @type {import('@jest/types').Config.InitialOptions} */10const config = {11 coveragePathIgnorePatterns: [/\/node_modules\//.source, /\/\S*fixture\S*\//.source],12 transform: { [/\.[jt]sx?$/.source]: ['babel-jest', babel] },13};14module.exports = config;15/**16 * Jest å¯ç¨ worker æ§è¡æµè¯ç¨ä¾æ¶ï¼ babel ç ConfigItem æ æ³è¢«åºååä¼ å
¥ worker ï¼17 * ä¹æ æ³éè¿ç¼åæ件å
±äº«ï¼å æ¤éè¦è½¬æ¢ä¸ä¸ã...
babel-jest_vx.x.x.js
Source: babel-jest_vx.x.x.js
1// flow-typed signature: 4c5da1c3fe02232aa441a60ecf7ce8cd2// flow-typed version: <<STUB>>/babel-jest_v^27.4.6/flow_v0.130.03/**4 * This is an autogenerated libdef stub for:5 *6 * 'babel-jest'7 *8 * Fill this stub out by replacing all the `any` types.9 *10 * Once filled out, we encourage you to share your work with the11 * community by sending a pull request to:12 * https://github.com/flowtype/flow-typed13 */14declare module 'babel-jest' {15 declare module.exports: any;16}17/**18 * We include stubs for each file inside this npm package in case you need to19 * require those files directly. Feel free to delete any files that aren't20 * needed.21 */22declare module 'babel-jest/build' {23 declare module.exports: any;24}25declare module 'babel-jest/build/loadBabelConfig' {26 declare module.exports: any;27}28// Filename aliases29declare module 'babel-jest/build/index' {30 declare module.exports: $Exports<'babel-jest/build'>;31}32declare module 'babel-jest/build/index.js' {33 declare module.exports: $Exports<'babel-jest/build'>;34}35declare module 'babel-jest/build/loadBabelConfig.js' {36 declare module.exports: $Exports<'babel-jest/build/loadBabelConfig'>;...
jest.babel.js
Source: jest.babel.js
1const { createHash } = require('crypto');2const { createTransformer } = require('babel-jest');3const path = require('path')4const { existsSync } = require('fs-extra')5function loadBabelConfig() {6 const babelConfigPath = path.resolve(process.cwd(), 'babel.config')7 if (existsSync(babelConfigPath)) {8 return require(babelConfigPath)9 }10 return {};11}12module.exports = {13 canInstrument: true,14 getCacheKey(sourceText) {15 const babelOptions = loadBabelConfig();16 return createHash('md5')17 .update('\0', 'utf8')18 .update(JSON.stringify(babelOptions))19 .update('\0', 'utf8')20 .update(sourceText)21 .update('\0', 'utf8')22 .update('components')23 .update('\0', 'utf8')24 .digest('hex');25 },26 process(sourceText, sourcePath, transformOptions) {27 const babelOptions = loadBabelConfig();28 const babelJest = createTransformer(babelOptions);29 return babelJest.process(sourceText, sourcePath, transformOptions);30 },...
How to test if a method returns an array of a class in Jest
How do node_modules packages read config files in the project root?
Jest: how to mock console when it is used by a third-party-library?
ERESOLVE unable to resolve dependency tree while installing a pacakge
Testing arguments with toBeCalledWith() in Jest
Is there assertCountEqual equivalent in javascript unittests jest library?
NodeJS: NOT able to set PERCY_TOKEN via package script with start-server-and-test
Jest: How to consume result of jest.genMockFromModule
How To Reset Manual Mocks In Jest
How to move '__mocks__' folder in Jest to /test?
Since Jest tests are runtime tests, they only have access to runtime information. You're trying to use a type, which is compile-time information. TypeScript should already be doing the type aspect of this for you. (More on that in a moment.)
The fact the tests only have access to runtime information has a couple of ramifications:
If it's valid for getAll
to return an empty array (because there aren't any entities to get), the test cannot tell you whether the array would have had Entity
elements in it if it hadn't been empty. All it can tell you is it got an array.
In the non-empty case, you have to check every element of the array to see if it's an Entity
. You've said Entity
is a class, not just a type, so that's possible. I'm not a user of Jest (I should be), but it doesn't seem to have a test specifically for this; it does have toBeTruthy
, though, and we can use every
to tell us if every element is an Entity
:
it('should return an array of Entity class', async () => {
const all = await service.getAll()
expect(all.every(e => e instanceof Entity)).toBeTruthy();
});
Beware, though, that all calls to every
on an empty array return true
, so again, that empty array issue raises its head.
If your Jest tests are written in TypeScript, you can improve on that by ensuring TypeScript tests the compile-time type of getAll
's return value:
it('should return an array of Entity class', async () => {
const all: Entity[] = await service.getAll()
// ^^^^^^^^^^
expect(all.every(e => e instanceof Entity)).toBeTruthy();
});
TypeScript will complain about that assignment at compile time if it's not valid, and Jest will complain at runtime if it sees an array containing a non-Entity
object.
But jonrsharpe has a good point: This test may not be useful vs. testing for specific values that should be there.
Check out the latest blogs from LambdaTest on this topic:
Node js has become one of the most popular frameworks in JavaScript today. Used by millions of developers, to develop thousands of project, node js is being extensively used. The more you develop, the better the testing you require to have a smooth, seamless application. This article shares the best practices for the testing node.in 2019, to deliver a robust web application or website.
Storybook offers a clean-room setting for isolating component testing. No matter how complex a component is, stories make it simple to explore it in all of its permutations. Before we discuss the Storybook testing in any browser, let us try and understand the fundamentals related to the Storybook framework and how it simplifies how we build UI components.
Quality Assurance (QA) is at the point of inflection and it is an exciting time to be in the field of QA as advanced digital technologies are influencing QA practices. As per a press release by Gartner, The encouraging part is that IT and automation will play a major role in transformation as the IT industry will spend close to $3.87 trillion in 2020, up from $3.76 trillion in 2019.
This article is a part of our Content Hub. For more in-depth resources, check out our content hub on WebDriverIO Tutorial and Selenium JavaScript Tutorial.
Having a strategy or plan can be the key to unlocking many successes, this is true to most contexts in life whether that be sport, business, education, and much more. The same is true for any company or organisation that delivers software/application solutions to their end users/customers. If you narrow that down even further from Engineering to Agile and then even to Testing or Quality Engineering, then strategy and planning is key at every level.
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.
|<p>it('check_object_of_Car', () => {</p><p>
expect(newCar()).toBeInstanceOf(Car);</p><p>
});</p>|
| :- |
Get 100 minutes of automation test minutes FREE!!