Best JavaScript code snippet using jest
normalize.js
Source: normalize.js
...499 'Running all tests instead.'500 )501 );502};503function validateExtensionsToTreatAsEsm(extensionsToTreatAsEsm) {504 if (!extensionsToTreatAsEsm || extensionsToTreatAsEsm.length === 0) {505 return;506 }507 function printConfig(opts) {508 const string = opts.map(ext => `'${ext}'`).join(', ');509 return _chalk().default.bold(`extensionsToTreatAsEsm: [${string}]`);510 }511 const extensionWithoutDot = extensionsToTreatAsEsm.some(512 ext => !ext.startsWith('.')513 );514 if (extensionWithoutDot) {515 throw createConfigError(` Option: ${printConfig(516 extensionsToTreatAsEsm517 )} includes a string that does not start with a period (${_chalk().default.bold(518 '.'519 )}).520 Please change your configuration to ${printConfig(521 extensionsToTreatAsEsm.map(ext => (ext.startsWith('.') ? ext : `.${ext}`))522 )}.`);523 }524 if (extensionsToTreatAsEsm.includes('.js')) {525 throw createConfigError(526 ` Option: ${printConfig(527 extensionsToTreatAsEsm528 )} includes ${_chalk().default.bold(529 "'.js'"530 )} which is always inferred based on ${_chalk().default.bold(531 'type'532 )} in its nearest ${_chalk().default.bold('package.json')}.`533 );534 }535 if (extensionsToTreatAsEsm.includes('.cjs')) {536 throw createConfigError(537 ` Option: ${printConfig(538 extensionsToTreatAsEsm539 )} includes ${_chalk().default.bold(540 "'.cjs'"541 )} which is always treated as CommonJS.`542 );543 }544 if (extensionsToTreatAsEsm.includes('.mjs')) {545 throw createConfigError(546 ` Option: ${printConfig(547 extensionsToTreatAsEsm548 )} includes ${_chalk().default.bold(549 "'.mjs'"550 )} which is always treated as an ECMAScript Module.`551 );552 }553}554async function normalize(555 initialOptions,556 argv,557 configPath,558 projectIndex = Infinity559) {560 var _options$haste, _argv$_;561 const {hasDeprecationWarnings} = (0, _jestValidate().validate)(562 initialOptions,563 {564 comment: _utils.DOCUMENTATION_NOTE,565 deprecatedConfig: _Deprecated.default,566 exampleConfig: _ValidConfig.default,567 recursiveDenylist: [568 'collectCoverageOnlyFrom', // 'coverageThreshold' allows to use 'global' and glob strings on the same569 // level, there's currently no way we can deal with such config570 'coverageThreshold',571 'globals',572 'moduleNameMapper',573 'testEnvironmentOptions',574 'transform'575 ]576 }577 );578 let options = normalizePreprocessor(579 normalizeReporters(580 normalizeMissingOptions(581 normalizeRootDir((0, _setFromArgv.default)(initialOptions, argv)),582 configPath,583 projectIndex584 )585 )586 );587 if (options.preset) {588 options = await setupPreset(options, options.preset);589 }590 if (!options.setupFilesAfterEnv) {591 options.setupFilesAfterEnv = [];592 }593 if (594 options.setupTestFrameworkScriptFile &&595 options.setupFilesAfterEnv.length > 0596 ) {597 throw createConfigError(` Options: ${_chalk().default.bold(598 'setupTestFrameworkScriptFile'599 )} and ${_chalk().default.bold(600 'setupFilesAfterEnv'601 )} cannot be used together.602 Please change your configuration to only use ${_chalk().default.bold(603 'setupFilesAfterEnv'604 )}.`);605 }606 if (options.setupTestFrameworkScriptFile) {607 options.setupFilesAfterEnv.push(options.setupTestFrameworkScriptFile);608 }609 options.testEnvironment = (0, _jestResolve().resolveTestEnvironment)({610 requireResolveFunction: require.resolve,611 rootDir: options.rootDir,612 testEnvironment:613 options.testEnvironment ||614 require.resolve(_Defaults.default.testEnvironment)615 });616 if (!options.roots && options.testPathDirs) {617 options.roots = options.testPathDirs;618 delete options.testPathDirs;619 }620 if (!options.roots) {621 options.roots = [options.rootDir];622 }623 if (624 !options.testRunner ||625 options.testRunner === 'circus' ||626 options.testRunner === 'jest-circus'627 ) {628 options.testRunner = require.resolve('jest-circus/runner');629 } else if (options.testRunner === 'jasmine2') {630 options.testRunner = require.resolve('jest-jasmine2');631 }632 if (!options.coverageDirectory) {633 options.coverageDirectory = path().resolve(options.rootDir, 'coverage');634 }635 setupBabelJest(options); // TODO: Type this properly636 const newOptions = {..._Defaults.default};637 if (options.resolver) {638 newOptions.resolver = (0, _utils.resolve)(null, {639 filePath: options.resolver,640 key: 'resolver',641 rootDir: options.rootDir642 });643 }644 validateExtensionsToTreatAsEsm(options.extensionsToTreatAsEsm);645 if (options.watchman == null) {646 options.watchman = _Defaults.default.watchman;647 }648 const optionKeys = Object.keys(options);649 optionKeys.reduce((newOptions, key) => {650 // The resolver has been resolved separately; skip it651 if (key === 'resolver') {652 return newOptions;653 } // This is cheating, because it claims that all keys of InitialOptions are Required.654 // We only really know it's Required for oldOptions[key], not for oldOptions.someOtherKey,655 // so oldOptions[key] is the only way it should be used.656 const oldOptions = options;657 let value;658 switch (key) {...
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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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