How to use addIstanbulInstrumentation method in Jest

Best JavaScript code snippet using jest


Source:index.js Github


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...108      )} as well.`109    );110  }111}112function addIstanbulInstrumentation(babelOptions, transformOptions) {113  if (transformOptions.instrument) {114    const copiedBabelOptions = {...babelOptions};115    copiedBabelOptions.auxiliaryCommentBefore = ' istanbul ignore next '; // Copied from jest-runtime transform.js116    copiedBabelOptions.plugins = (copiedBabelOptions.plugins || []).concat([117      [118        babelIstanbulPlugin,119        {120          // files outside `cwd` will not be instrumented121          cwd: transformOptions.config.cwd,122          exclude: []123        }124      ]125    ]);126    return copiedBabelOptions;127  }128  return babelOptions;129}130function getCacheKeyFromConfig(131  sourceText,132  sourcePath,133  babelOptions,134  transformOptions135) {136  const {config, configString, instrument} = transformOptions;137  const configPath = [babelOptions.config || '', babelOptions.babelrc || ''];138  return (0, _crypto().createHash)('md5')139    .update(THIS_FILE)140    .update('\0', 'utf8')141    .update(JSON.stringify(babelOptions.options))142    .update('\0', 'utf8')143    .update(sourceText)144    .update('\0', 'utf8')145    .update(path().relative(config.rootDir, sourcePath))146    .update('\0', 'utf8')147    .update(configString)148    .update('\0', 'utf8')149    .update(configPath.join(''))150    .update('\0', 'utf8')151    .update(instrument ? 'instrument' : '')152    .update('\0', 'utf8')153    .update(process.env.NODE_ENV || '')154    .update('\0', 'utf8')155    .update(process.env.BABEL_ENV || '')156    .update('\0', 'utf8')157    .update(process.version)158    .digest('hex');159}160function loadBabelConfig(cwd, filename, transformOptions) {161  const babelConfig = (0, _loadBabelConfig.loadPartialConfig)(transformOptions);162  assertLoadedBabelConfig(babelConfig, cwd, filename);163  return babelConfig;164}165async function loadBabelConfigAsync(cwd, filename, transformOptions) {166  const babelConfig = await (0, _loadBabelConfig.loadPartialConfigAsync)(167    transformOptions168  );169  assertLoadedBabelConfig(babelConfig, cwd, filename);170  return babelConfig;171}172function loadBabelOptions(173  cwd,174  filename,175  transformOptions,176  jestTransformOptions177) {178  const {options} = loadBabelConfig(cwd, filename, transformOptions);179  return addIstanbulInstrumentation(options, jestTransformOptions);180}181async function loadBabelOptionsAsync(182  cwd,183  filename,184  transformOptions,185  jestTransformOptions186) {187  const {options} = await loadBabelConfigAsync(cwd, filename, transformOptions);188  return addIstanbulInstrumentation(options, jestTransformOptions);189}190const createTransformer = userOptions => {191  var _inputOptions$plugins, _inputOptions$presets;192  const inputOptions =193    userOptions !== null && userOptions !== void 0 ? userOptions : {};194  const options = {195    ...inputOptions,196    caller: {197      name: 'babel-jest',198      supportsDynamicImport: false,199      supportsExportNamespaceFrom: false,200      supportsStaticESM: false,201      supportsTopLevelAwait: false,202      ...inputOptions.caller...

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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.


  1. What is Jest Framework
  2. 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.
  3. Jest Installation - All the prerequisites and set up steps needed to help you start Jest automation testing.
  4. Using Jest with NodeJS Project - Learn how to leverage Jest framework to automate testing using a NodeJS Project.
  5. Writing First Test for Jest Framework - Get started with code-based tutorial to help you write and execute your first Jest framework testing script.
  6. Jest Vocabulary - Learn the industry renowned and official jargons of the Jest framework by digging deep into the Jest vocabulary.
  7. Unit Testing with Jest - Step-by-step tutorial to help you execute unit testing with Jest framework.
  8. Jest Basics - Learn about the most pivotal and basic features which makes Jest special.
  9. 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.
  10. 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. -

|<p>it('check_object_of_Car', () => {</p><p> expect(newCar()).toBeInstanceOf(Car);</p><p> });</p>| | :- |

  1. 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.
  2. 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.
  3. HTML Report Generation - Learn how to create a comprehensive HTML report based on your Jest test execution.
  4. Testing React app using Jest Framework - Learn how to test your react web-application with Jest framework in this detailed Jest tutorial.
  5. 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.
  6. 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.
  7. 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.
  8. Jest vs Mocha vs Jasmine - Learn the key differences between the most popular JavaScript-based testing frameworks i.e. Jest, Mocha, and Jasmine.
  9. Jest FAQs(Frequently Asked Questions) - Explore the most commonly asked questions around Jest framework, with their answers.

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