How to use returnArguments method in Jest

Best JavaScript code snippet using jest


Source:arguments-apply.js Github


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1// Copyright 2009 the V8 project authors. All rights reserved.2// Redistribution and use in source and binary forms, with or without3// modification, are permitted provided that the following conditions are4// met:5//6// * Redistributions of source code must retain the above copyright7// notice, this list of conditions and the following disclaimer.8// * Redistributions in binary form must reproduce the above9// copyright notice, this list of conditions and the following10// disclaimer in the documentation and/or other materials provided11// with the distribution.12// * Neither the name of Google Inc. nor the names of its13// contributors may be used to endorse or promote products derived14// from this software without specific prior written permission.15//16// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS17// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT18// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR19// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT20// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,21// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT22// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,23// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY24// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT25// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE26// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.27function ReturnArguments() {28 return arguments;29}30function ReturnReceiver() {31 return this;32}33function Global() {34 return ReturnArguments.apply(this, arguments);35}36assertEquals(0, Global().length);37assertEquals(1, Global(1).length);38assertEquals(2, Global(2)[0]);39assertEquals(2, Global(3, 4).length);40assertEquals(3, Global(3, 4)[0]);41assertEquals(4, Global(3, 4)[1]);42function Local() {43 var object = { f: ReturnArguments };44 return object.f.apply(this, arguments);45}46assertEquals(0, Local().length);47assertEquals(1, Local(1).length);48assertEquals(2, Local(2)[0]);49assertEquals(2, Local(3, 4).length);50assertEquals(3, Local(3, 4)[0]);51assertEquals(4, Local(3, 4)[1]);52function ShadowArguments() {53 var arguments = [3, 4];54 return ReturnArguments.apply(this, arguments);55}56assertEquals(2, ShadowArguments().length);57assertEquals(3, ShadowArguments()[0]);58assertEquals(4, ShadowArguments()[1]);59function NonObjectReceiver(receiver) {60 return ReturnReceiver.apply(receiver, arguments);61}62assertEquals(Object(42), NonObjectReceiver(42));63assertEquals("object", typeof NonObjectReceiver(42));64assertInstanceof(NonObjectReceiver(42), Number);65assertSame(this, NonObjectReceiver(null));66assertSame(this, NonObjectReceiver(void 0));67function FunctionReceiver() {68 return ReturnReceiver.apply(Object, arguments);69}70assertTrue(Object === FunctionReceiver());71function ShadowApply() {72 function f() { return 42; }73 f.apply = function() { return 87; }74 return f.apply(this, arguments);75}76assertEquals(87, ShadowApply());77assertEquals(87, ShadowApply(1));78assertEquals(87, ShadowApply(1, 2));79function CallNonFunction() {80 var object = { apply: Function.prototype.apply };81 return object.apply(this, arguments);82}83assertThrows(CallNonFunction, TypeError);84// Make sure that the stack after the apply optimization is85// in a valid state.86function SimpleStackCheck() {87 var sentinel = 42;88 var result = ReturnArguments.apply(this, arguments);89 assertTrue(result != null);90 assertEquals(42, sentinel);91}92SimpleStackCheck();93function ShadowArgumentsWithConstant() {94 var arguments = null;95 return ReturnArguments.apply(this, arguments);96}97assertEquals(0, ShadowArgumentsWithConstant().length);98assertEquals(0, ShadowArgumentsWithConstant(1).length);99assertEquals(0, ShadowArgumentsWithConstant(1, 2).length);100// Make sure we can deal with unfolding lots of arguments on the101// stack even in the presence of the apply optimizations.102var array = new Array(2048);...

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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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