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How to use replaceMatchedToAsymmetricMatcher method in Jest

Best JavaScript code snippet using jest

index.js

Source:index.js

...320    return expectedLine + '\n' + receivedLine;321  }322  if (isLineDiffable(expected, received)) {323    const {replacedExpected, replacedReceived} =324      replaceMatchedToAsymmetricMatcher(325        (0, _deepCyclicCopyReplaceable.default)(expected),326        (0, _deepCyclicCopyReplaceable.default)(received),327        [],328        []329      );330    const difference = (0, _jestDiff.diff)(replacedExpected, replacedReceived, {331      aAnnotation: expectedLabel,332      bAnnotation: receivedLabel,333      expand,334      includeChangeCounts: true335    });336    if (337      typeof difference === 'string' &&338      difference.includes('- ' + expectedLabel) &&339      difference.includes('+ ' + receivedLabel)340    ) {341      return difference;342    }343  }344  const printLabel = getLabelPrinter(expectedLabel, receivedLabel);345  const expectedLine = printLabel(expectedLabel) + printExpected(expected);346  const receivedLine =347    printLabel(receivedLabel) +348    (stringify(expected) === stringify(received)349      ? 'serializes to the same string'350      : printReceived(received));351  return expectedLine + '\n' + receivedLine;352}; // Sometimes, e.g. when comparing two numbers, the output from jest-diff353// does not contain more information than the `Expected:` / `Received:` already gives.354// In those cases, we do not print a diff to make the output shorter and not redundant.355exports.printDiffOrStringify = printDiffOrStringify;356const shouldPrintDiff = (actual, expected) => {357  if (typeof actual === 'number' && typeof expected === 'number') {358    return false;359  }360  if (typeof actual === 'bigint' && typeof expected === 'bigint') {361    return false;362  }363  if (typeof actual === 'boolean' && typeof expected === 'boolean') {364    return false;365  }366  return true;367};368function replaceMatchedToAsymmetricMatcher(369  replacedExpected,370  replacedReceived,371  expectedCycles,372  receivedCycles373) {374  if (!_Replaceable.default.isReplaceable(replacedExpected, replacedReceived)) {375    return {376      replacedExpected,377      replacedReceived378    };379  }380  if (381    expectedCycles.includes(replacedExpected) ||382    receivedCycles.includes(replacedReceived)383  ) {384    return {385      replacedExpected,386      replacedReceived387    };388  }389  expectedCycles.push(replacedExpected);390  receivedCycles.push(replacedReceived);391  const expectedReplaceable = new _Replaceable.default(replacedExpected);392  const receivedReplaceable = new _Replaceable.default(replacedReceived);393  expectedReplaceable.forEach((expectedValue, key) => {394    const receivedValue = receivedReplaceable.get(key);395    if (isAsymmetricMatcher(expectedValue)) {396      if (expectedValue.asymmetricMatch(receivedValue)) {397        receivedReplaceable.set(key, expectedValue);398      }399    } else if (isAsymmetricMatcher(receivedValue)) {400      if (receivedValue.asymmetricMatch(expectedValue)) {401        expectedReplaceable.set(key, receivedValue);402      }403    } else if (404      _Replaceable.default.isReplaceable(expectedValue, receivedValue)405    ) {406      const replaced = replaceMatchedToAsymmetricMatcher(407        expectedValue,408        receivedValue,409        expectedCycles,410        receivedCycles411      );412      expectedReplaceable.set(key, replaced.replacedExpected);413      receivedReplaceable.set(key, replaced.replacedReceived);414    }415  });416  return {417    replacedExpected: expectedReplaceable.object,418    replacedReceived: receivedReplaceable.object419  };420}...

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.