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How to use promisifyLifeCycleFunction method in Jest

Best JavaScript code snippet using jest

jasmineAsyncInstall.js

Source:jasmineAsyncInstall.js

...15var Promise = global[Symbol.for('jest-native-promise')] || global.Promise;16function isPromise(obj) {17  return obj && typeof obj.then === 'function';18}19function promisifyLifeCycleFunction(originalFn, env) {20  return function(fn, timeout) {21    if (!fn) {22      return originalFn.call(env);23    }24    const hasDoneCallback = typeof fn === 'function' && fn.length > 0;25    if (hasDoneCallback) {26      // Jasmine will handle it27      return originalFn.call(env, fn, timeout);28    }29    const extraError = new Error(); // Without this line v8 stores references to all closures30    // in the stack in the Error object. This line stringifies the stack31    // property to allow garbage-collecting objects on the stack32    // https://crbug.com/v8/714233    extraError.stack = extraError.stack; // We make *all* functions async and run `done` right away if they34    // didn't return a promise.35    const asyncJestLifecycle = function asyncJestLifecycle(done) {36      const wrappedFn = (0, _isGeneratorFn.default)(fn)37        ? _co.default.wrap(fn)38        : fn;39      const returnValue = wrappedFn.call({});40      if (isPromise(returnValue)) {41        returnValue.then(done.bind(null, null), error => {42          const _isError = (0, _isError3.default)(error),43            checkIsError = _isError.isError,44            message = _isError.message;45          if (message) {46            extraError.message = message;47          }48          done.fail(checkIsError ? error : extraError);49        });50      } else {51        done();52      }53    };54    return originalFn.call(env, asyncJestLifecycle, timeout);55  };56} // Similar to promisifyLifeCycleFunction but throws an error57// when the return value is neither a Promise nor `undefined`58function promisifyIt(originalFn, env, jasmine) {59  return function(specName, fn, timeout) {60    if (!fn) {61      const spec = originalFn.call(env, specName);62      spec.pend('not implemented');63      return spec;64    }65    const hasDoneCallback = fn.length > 0;66    if (hasDoneCallback) {67      return originalFn.call(env, specName, fn, timeout);68    }69    const extraError = new Error(); // Without this line v8 stores references to all closures70    // in the stack in the Error object. This line stringifies the stack71    // property to allow garbage-collecting objects on the stack72    // https://crbug.com/v8/714273    extraError.stack = extraError.stack;74    const asyncJestTest = function asyncJestTest(done) {75      const wrappedFn = (0, _isGeneratorFn.default)(fn)76        ? _co.default.wrap(fn)77        : fn;78      const returnValue = wrappedFn.call({});79      if (isPromise(returnValue)) {80        returnValue.then(done.bind(null, null), error => {81          const _isError2 = (0, _isError3.default)(error),82            checkIsError = _isError2.isError,83            message = _isError2.message;84          if (message) {85            extraError.message = message;86          }87          if (jasmine.Spec.isPendingSpecException(error)) {88            env.pending(message);89            done();90          } else {91            done.fail(checkIsError ? error : extraError);92          }93        });94      } else if (returnValue === undefined) {95        done();96      } else {97        done.fail(98          new Error(99            'Jest: `it` and `test` must return either a Promise or undefined.'100          )101        );102      }103    };104    return originalFn.call(env, specName, asyncJestTest, timeout);105  };106}107function makeConcurrent(originalFn, env, mutex) {108  return function(specName, fn, timeout) {109    if (110      env != null &&111      !env.specFilter({112        getFullName: () => specName || ''113      })114    ) {115      return originalFn.call(env, specName, () => Promise.resolve(), timeout);116    }117    let promise;118    try {119      promise = mutex(() => {120        const promise = fn();121        if (isPromise(promise)) {122          return promise;123        }124        throw new Error(125          `Jest: concurrent test "${specName}" must return a Promise.`126        );127      });128    } catch (error) {129      return originalFn.call(env, specName, () => Promise.reject(error));130    }131    return originalFn.call(env, specName, () => promise, timeout);132  };133}134function jasmineAsyncInstall(globalConfig, global) {135  const jasmine = global.jasmine;136  const mutex = (0, _throat.default)(globalConfig.maxConcurrency);137  const env = jasmine.getEnv();138  env.it = promisifyIt(env.it, env, jasmine);139  env.fit = promisifyIt(env.fit, env, jasmine);140  global.it.concurrent = (env => {141    const concurrent = makeConcurrent(env.it, env, mutex);142    concurrent.only = makeConcurrent(env.fit, env, mutex);143    concurrent.skip = makeConcurrent(env.xit, env, mutex);144    return concurrent;145  })(env);146  global.fit.concurrent = makeConcurrent(env.fit, env, mutex);147  env.afterAll = promisifyLifeCycleFunction(env.afterAll, env);148  env.afterEach = promisifyLifeCycleFunction(env.afterEach, env);149  env.beforeAll = promisifyLifeCycleFunction(env.beforeAll, env);150  env.beforeEach = promisifyLifeCycleFunction(env.beforeEach, env);...

jasmine_async.js

Source:jasmine_async.js

...8                                                                                           * 9                                                                                           */ /**10                                                                                               * This module adds ability to test async promise code with jasmine by11                                                                                               * returning a promise from `it/test` and `before/afterEach/All` blocks.12                                                                                               */function promisifyLifeCycleFunction(originalFn, env) {return function (fn, timeout) {if (!fn) {return originalFn.call(env);}const hasDoneCallback = fn.length > 0;if (hasDoneCallback) {// Jasmine will handle it13      return originalFn.call(env, fn, timeout);} // We make *all* functions async and run `done` right away if they14    // didn't return a promise.15    const asyncFn = function (done) {const returnValue = fn.call({});if (isPromise(returnValue)) {returnValue.then(done.bind(null, null), done.fail);} else {done();}};return originalFn.call(env, asyncFn, timeout);};} // Similar to promisifyLifeCycleFunction but throws an error16// when the return value is neither a Promise nor `undefined`...

jasmine-async.js

Source:jasmine-async.js

...11   * 12   */ /**13       * This module adds ability to test async promise code with jasmine by14       * returning a promise from `it/test` and `before/afterEach/All` blocks.15       */function promisifyLifeCycleFunction(originalFn, env) {return function (fn, timeout) {if (!fn) {return originalFn.call(env);}const hasDoneCallback = fn.length > 0;if (hasDoneCallback) {// Jasmine will handle it16      return originalFn.call(env, fn, timeout);17    }18    // We make *all* functions async and run `done` right away if they19    // didn't return a promise.20    const asyncFn = function (done) {21      const returnValue = fn.call({});22      if (isPromise(returnValue)) {23        returnValue.then(done, done.fail);24      } else {25        done();26      }27    };28    return originalFn.call(env, asyncFn, timeout);29  };30}31// Similar to promisifyLifeCycleFunction but throws an error32// when the return value is neither a Promise nor `undefined`33function promisifyIt(originalFn, env) {34  return function (specName, fn, timeout) {35    if (!fn) {36      const spec = originalFn.call(env, specName);37      spec.pend('not implemented');38      return spec;39    }40    const hasDoneCallback = fn.length > 0;41    if (hasDoneCallback) {42      return originalFn.call(env, specName, fn, timeout);43    }44    const asyncFn = function (done) {45      const returnValue = fn.call({});46      if (isPromise(returnValue)) {47        returnValue.then(done, done.fail);48      } else if (returnValue === undefined) {49        done();50      } else {51        done.fail(52        new Error(53        'Jest: `it` and `test` must return either a Promise or undefined.'));54      }55    };56    return originalFn.call(env, specName, asyncFn, timeout);57  };58}59function makeConcurrent(originalFn, env) {60  return function (specName, fn, timeout) {61    if (env != null && !env.specFilter({ getFullName: () => specName || '' })) {62      return originalFn.call(env, specName, () => Promise.resolve(), timeout);63    }64    let promise;65    try {66      promise = fn();67      if (!isPromise(promise)) {68        throw new Error(69        `Jest: concurrent test "${specName}" must return a Promise.`);70      }71    } catch (error) {72      return originalFn.call(env, specName, () => Promise.reject(error));73    }74    return originalFn.call(env, specName, () => promise, timeout);75  };76}77function install(global) {78  const jasmine = global.jasmine;79  const env = jasmine.getEnv();80  env.it = promisifyIt(env.it, env);81  env.fit = promisifyIt(env.fit, env);82  global.it.concurrent = makeConcurrent(env.it, env);83  global.it.concurrent.only = makeConcurrent(env.fit, env);84  global.it.concurrent.skip = makeConcurrent(env.xit, env);85  global.fit.concurrent = makeConcurrent(env.fit);86  env.afterAll = promisifyLifeCycleFunction(env.afterAll, env);87  env.afterEach = promisifyLifeCycleFunction(env.afterEach, env);88  env.beforeAll = promisifyLifeCycleFunction(env.beforeAll, env);89  env.beforeEach = promisifyLifeCycleFunction(env.beforeEach, env);90}91module.exports = {...

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.