Best JavaScript code snippet using jest
index.js
Source: index.js
...46 // A string passed to `--config`, which is either a direct path to the config47 // or a path to directory containing `package.json` or `jest.conf.js`48 } else if (!skipArgvConfigOption && typeof argv.config == 'string') {49 configPath = resolveConfigPath(argv.config, process.cwd());50 rawOptions = readConfigFileAndSetRootDir(configPath);51 } else {52 // Otherwise just try to find config in the current rootDir.53 configPath = resolveConfigPath(packageRoot, process.cwd());54 rawOptions = readConfigFileAndSetRootDir(configPath);55 }56 const {options, hasDeprecationWarnings} = normalize(rawOptions, argv);57 const {globalConfig, projectConfig} = getConfigs(options);58 return {59 configPath,60 globalConfig,61 hasDeprecationWarnings,62 projectConfig,63 };64}65const getConfigs = (66 options: Object,67): {globalConfig: GlobalConfig, projectConfig: ProjectConfig} => {68 return {...
readConfigFileAndSetRootDir.js
Source: readConfigFileAndSetRootDir.js
...79// Read the configuration and set its `rootDir`80// 1. If it's a `package.json` file, we look into its "jest" property81// 2. For any other file, we just require it. If we receive an 'ERR_REQUIRE_ESM'82// from node, perform a dynamic import instead.83async function readConfigFileAndSetRootDir(configPath) {84 const isJSON = configPath.endsWith(_constants.JEST_CONFIG_EXT_JSON);85 let configObject;86 try {87 configObject = require(configPath);88 } catch (error) {89 if (error.code === 'ERR_REQUIRE_ESM') {90 try {91 const configUrl = (0, _url().pathToFileURL)(configPath); // node `import()` supports URL, but TypeScript doesn't know that92 const importedConfig = await import(configUrl.href);93 if (!importedConfig.default) {94 throw new Error(95 `Jest: Failed to load mjs config file ${configPath} - did you use a default export?`96 );97 }...
jest-config_vx.x.x.js
Source: jest-config_vx.x.x.js
1// flow-typed signature: 50a4f858d000ca6d3fc96543a7d866a02// flow-typed version: <<STUB>>/jest-config_v^24.1.0/flow_v0.92.13/**4 * This is an autogenerated libdef stub for:5 *6 * 'jest-config'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 'jest-config' {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 'jest-config/build/constants' {23 declare module.exports: any;24}25declare module 'jest-config/build/Defaults' {26 declare module.exports: any;27}28declare module 'jest-config/build/Deprecated' {29 declare module.exports: any;30}31declare module 'jest-config/build/Descriptions' {32 declare module.exports: any;33}34declare module 'jest-config/build/getCacheDirectory' {35 declare module.exports: any;36}37declare module 'jest-config/build/getMaxWorkers' {38 declare module.exports: any;39}40declare module 'jest-config/build/index' {41 declare module.exports: any;42}43declare module 'jest-config/build/normalize' {44 declare module.exports: any;45}46declare module 'jest-config/build/readConfigFileAndSetRootDir' {47 declare module.exports: any;48}49declare module 'jest-config/build/ReporterValidationErrors' {50 declare module.exports: any;51}52declare module 'jest-config/build/resolveConfigPath' {53 declare module.exports: any;54}55declare module 'jest-config/build/setFromArgv' {56 declare module.exports: any;57}58declare module 'jest-config/build/utils' {59 declare module.exports: any;60}61declare module 'jest-config/build/validatePattern' {62 declare module.exports: any;63}64declare module 'jest-config/build/ValidConfig' {65 declare module.exports: any;66}67declare module 'jest-config/build/vendor/jsonlint' {68 declare module.exports: any;69}70// Filename aliases71declare module 'jest-config/build/constants.js' {72 declare module.exports: $Exports<'jest-config/build/constants'>;73}74declare module 'jest-config/build/Defaults.js' {75 declare module.exports: $Exports<'jest-config/build/Defaults'>;76}77declare module 'jest-config/build/Deprecated.js' {78 declare module.exports: $Exports<'jest-config/build/Deprecated'>;79}80declare module 'jest-config/build/Descriptions.js' {81 declare module.exports: $Exports<'jest-config/build/Descriptions'>;82}83declare module 'jest-config/build/getCacheDirectory.js' {84 declare module.exports: $Exports<'jest-config/build/getCacheDirectory'>;85}86declare module 'jest-config/build/getMaxWorkers.js' {87 declare module.exports: $Exports<'jest-config/build/getMaxWorkers'>;88}89declare module 'jest-config/build/index.js' {90 declare module.exports: $Exports<'jest-config/build/index'>;91}92declare module 'jest-config/build/normalize.js' {93 declare module.exports: $Exports<'jest-config/build/normalize'>;94}95declare module 'jest-config/build/readConfigFileAndSetRootDir.js' {96 declare module.exports: $Exports<'jest-config/build/readConfigFileAndSetRootDir'>;97}98declare module 'jest-config/build/ReporterValidationErrors.js' {99 declare module.exports: $Exports<'jest-config/build/ReporterValidationErrors'>;100}101declare module 'jest-config/build/resolveConfigPath.js' {102 declare module.exports: $Exports<'jest-config/build/resolveConfigPath'>;103}104declare module 'jest-config/build/setFromArgv.js' {105 declare module.exports: $Exports<'jest-config/build/setFromArgv'>;106}107declare module 'jest-config/build/utils.js' {108 declare module.exports: $Exports<'jest-config/build/utils'>;109}110declare module 'jest-config/build/validatePattern.js' {111 declare module.exports: $Exports<'jest-config/build/validatePattern'>;112}113declare module 'jest-config/build/ValidConfig.js' {114 declare module.exports: $Exports<'jest-config/build/ValidConfig'>;115}116declare module 'jest-config/build/vendor/jsonlint.js' {117 declare module.exports: $Exports<'jest-config/build/vendor/jsonlint'>;...
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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:
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|<p>it('check_object_of_Car', () => {</p><p>
expect(newCar()).toBeInstanceOf(Car);</p><p>
});</p>|
| :- |
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