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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  }...

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Unit Testing with Jest - Step-by-step tutorial to help you execute unit testing with Jest framework.
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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.
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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.
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Jest FAQs(Frequently Asked Questions) - Explore the most commonly asked questions around Jest framework, with their answers.