KaneAI - World’s First E2E Software Testing Agent.Signup for Private Beta Join TestMu Conference

How to use writeCodeCacheFile method in Jest

Best JavaScript code snippet using jest

ScriptTransformer.js

Source:ScriptTransformer.js

...251      writeCacheFile(sourceMapPath, sourceMapContent);252    } else {253      sourceMapPath = null;254    }255    writeCodeCacheFile(cacheFilePath, code);256    return {257      code,258      mapCoverage,259      sourceMapPath,260    };261  }262  _transformAndBuildScript(263    filename: Path,264    options: ?Options,265    instrument: boolean,266    fileSource?: string,267  ): TransformResult {268    const isInternalModule = !!(options && options.isInternalModule);269    const isCoreModule = !!(options && options.isCoreModule);270    const content = stripShebang(271      fileSource || fs.readFileSync(filename, 'utf8'),272    );273    let wrappedCode: string;274    let sourceMapPath: ?string = null;275    let mapCoverage = false;276    const willTransform =277      !isInternalModule &&278      !isCoreModule &&279      (this._shouldTransform(filename) || instrument);280    try {281      const extraGlobals = (options && options.extraGlobals) || [];282      if (willTransform) {283        const transformedSource = this.transformSource(284          filename,285          content,286          instrument,287        );288        wrappedCode = wrap(transformedSource.code, ...extraGlobals);289        sourceMapPath = transformedSource.sourceMapPath;290        mapCoverage = transformedSource.mapCoverage;291      } else {292        wrappedCode = wrap(content, ...extraGlobals);293      }294      return {295        mapCoverage,296        script: new vm.Script(wrappedCode, {297          displayErrors: true,298          filename: isCoreModule ? 'jest-nodejs-core-' + filename : filename,299        }),300        sourceMapPath,301      };302    } catch (e) {303      if (e.codeFrame) {304        e.stack = e.message + '\n' + e.codeFrame;305      }306      if (307        e instanceof SyntaxError &&308        e.message.includes('Unexpected token') &&309        !e.message.includes(' expected')310      ) {311        throw enhanceUnexpectedTokenMessage(e);312      }313      throw e;314    }315  }316  transform(317    filename: Path,318    options: Options,319    fileSource?: string,320  ): TransformResult {321    let scriptCacheKey = null;322    let instrument = false;323    let result = '';324    if (!options.isCoreModule) {325      instrument = shouldInstrument(filename, options, this._config);326      scriptCacheKey = getScriptCacheKey(filename, instrument);327      result = this._cache.transformedFiles.get(scriptCacheKey);328    }329    if (result) {330      return result;331    }332    result = this._transformAndBuildScript(333      filename,334      options,335      instrument,336      fileSource,337    );338    if (scriptCacheKey) {339      this._cache.transformedFiles.set(scriptCacheKey, result);340    }341    return result;342  }343  _shouldTransform(filename: Path): boolean {344    const ignoreRegexp = this._cache.ignorePatternsRegExp;345    const isIgnored = ignoreRegexp ? ignoreRegexp.test(filename) : false;346    return (347      !!this._config.transform && !!this._config.transform.length && !isIgnored348    );349  }350}351const removeFile = (path: Path) => {352  try {353    fs.unlinkSync(path);354  } catch (e) {}355};356const stripShebang = content => {357  // If the file data starts with a shebang remove it. Leaves the empty line358  // to keep stack trace line numbers correct.359  if (content.startsWith('#!')) {360    return content.replace(/^#!.*/, '');361  } else {362    return content;363  }364};365/**366 * This is like `writeCacheFile` but with an additional sanity checksum. We367 * cannot use the same technique for source maps because we expose source map368 * cache file paths directly to callsites, with the expectation they can read369 * it right away. This is not a great system, because source map cache file370 * could get corrupted, out-of-sync, etc.371 */372function writeCodeCacheFile(cachePath: Path, code: string) {373  const checksum = crypto374    .createHash('md5')375    .update(code)376    .digest('hex');377  writeCacheFile(cachePath, checksum + '\n' + code);378}379/**380 * Read counterpart of `writeCodeCacheFile`. We verify that the content of the381 * file matches the checksum, in case some kind of corruption happened. This382 * could happen if an older version of `jest-runtime` writes non-atomically to383 * the same cache, for example.384 */385function readCodeCacheFile(cachePath: Path): ?string {386  const content = readCacheFile(cachePath);...

script_transformer.js

Source:script_transformer.js

...235      writeCacheFile(sourceMapPath, sourceMapContent);236    } else {237      sourceMapPath = null;238    }239    writeCodeCacheFile(cacheFilePath, code);240    return {241      code,242      sourceMapPath,243    };244  }245  _transformAndBuildScript(246    filename: Path,247    options: ?Options,248    instrument: boolean,249    fileSource?: string,250  ): TransformResult {251    const isInternalModule = !!(options && options.isInternalModule);252    const content = stripShebang(253      fileSource || fs.readFileSync(filename, 'utf8'),254    );255    let wrappedCode: string;256    let sourceMapPath: ?string = null;257    const willTransform =258      !isInternalModule &&259      (shouldTransform(filename, this._config) || instrument);260    try {261      if (willTransform) {262        const transformedSource = this.transformSource(263          filename,264          content,265          instrument,266          !!(options && options.mapCoverage),267        );268        wrappedCode = wrap(transformedSource.code);269        sourceMapPath = transformedSource.sourceMapPath;270      } else {271        wrappedCode = wrap(content);272      }273      return {274        script: new vm.Script(wrappedCode, {displayErrors: true, filename}),275        sourceMapPath,276      };277    } catch (e) {278      if (e.codeFrame) {279        e.stack = e.codeFrame;280      }281      throw e;282    }283  }284  transform(285    filename: Path,286    options: Options,287    fileSource?: string,288  ): TransformResult {289    const instrument = shouldInstrument(filename, options, this._config);290    const scriptCacheKey = getScriptCacheKey(291      filename,292      this._config,293      instrument,294    );295    let result = cache.get(scriptCacheKey);296    if (result) {297      return result;298    } else {299      result = this._transformAndBuildScript(300        filename,301        options,302        instrument,303        fileSource,304      );305      cache.set(scriptCacheKey, result);306      return result;307    }308  }309}310const removeFile = (path: Path) => {311  try {312    fs.unlinkSync(path);313  } catch (e) {}314};315const stripShebang = content => {316  // If the file data starts with a shebang remove it. Leaves the empty line317  // to keep stack trace line numbers correct.318  if (content.startsWith('#!')) {319    return content.replace(/^#!.*/, '');320  } else {321    return content;322  }323};324/**325 * This is like `writeCacheFile` but with an additional sanity checksum. We326 * cannot use the same technique for source maps because we expose source map327 * cache file paths directly to callsites, with the expectation they can read328 * it right away. This is not a great system, because source map cache file329 * could get corrupted, out-of-sync, etc.330 */331function writeCodeCacheFile(cachePath: Path, code: string) {332  const checksum = crypto.createHash('md5').update(code).digest('hex');333  writeCacheFile(cachePath, checksum + '\n' + code);334}335/**336 * Read counterpart of `writeCodeCacheFile`. We verify that the content of the337 * file matches the checksum, in case some kind of corruption happened. This338 * could happen if an older version of `jest-runtime` writes non-atomically to339 * the same cache, for example.340 */341function readCodeCacheFile(cachePath: Path): ?string {342  const content = readCacheFile(cachePath);343  if (content == null) {344    return null;345  }...

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.