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How to use stripAddedIndentation method in Jest

Best JavaScript code snippet using jest

index.js

Source:index.js

...72    count +73    '`'74  );75};76function stripAddedIndentation(inlineSnapshot) {77  // Find indentation if exists.78  const match = inlineSnapshot.match(INDENTATION_REGEX);79  if (!match || !match[1]) {80    // No indentation.81    return inlineSnapshot;82  }83  const indentation = match[1];84  const lines = inlineSnapshot.split('\n');85  if (lines.length <= 2) {86    // Must be at least 3 lines.87    return inlineSnapshot;88  }89  if (lines[0].trim() !== '' || lines[lines.length - 1].trim() !== '') {90    // If not blank first and last lines, abort.91    return inlineSnapshot;92  }93  for (let i = 1; i < lines.length - 1; i++) {94    if (lines[i] !== '') {95      if (lines[i].indexOf(indentation) !== 0) {96        // All lines except first and last should either be blank or have the same97        // indent as the first line (or more). If this isn't the case we don't98        // want to touch the snapshot at all.99        return inlineSnapshot;100      }101      lines[i] = lines[i].substr(indentation.length);102    }103  } // Last line is a special case because it won't have the same indent as others104  // but may still have been given some indent to line up.105  lines[lines.length - 1] = ''; // Return inline snapshot, now at indent 0.106  inlineSnapshot = lines.join('\n');107  return inlineSnapshot;108}109const fileExists = (filePath, hasteFS) =>110  hasteFS.exists(filePath) || jestExistsFile(filePath);111const cleanup = (hasteFS, update, snapshotResolver, testPathIgnorePatterns) => {112  const pattern = '\\.' + _SnapshotResolver.EXTENSION + '$';113  const files = hasteFS.matchFiles(pattern);114  let testIgnorePatternsRegex = null;115  if (testPathIgnorePatterns && testPathIgnorePatterns.length > 0) {116    testIgnorePatternsRegex = new RegExp(testPathIgnorePatterns.join('|'));117  }118  const list = files.filter(snapshotFile => {119    const testPath = snapshotResolver.resolveTestPath(snapshotFile); // ignore snapshots of ignored tests120    if (testIgnorePatternsRegex && testIgnorePatternsRegex.test(testPath)) {121      return false;122    }123    if (!fileExists(testPath, hasteFS)) {124      if (update === 'all') {125        fs.unlinkSync(snapshotFile);126      }127      return true;128    }129    return false;130  });131  return {132    filesRemoved: list.length,133    filesRemovedList: list134  };135};136const toMatchSnapshot = function (received, propertiesOrHint, hint) {137  const matcherName = 'toMatchSnapshot';138  let properties;139  const length = arguments.length;140  if (length === 2 && typeof propertiesOrHint === 'string') {141    hint = propertiesOrHint;142  } else if (length >= 2) {143    if (typeof propertiesOrHint !== 'object' || propertiesOrHint === null) {144      const options = {145        isNot: this.isNot,146        promise: this.promise147      };148      let printedWithType = (0, _jestMatcherUtils.printWithType)(149        'Expected properties',150        propertiesOrHint,151        _printSnapshot.printExpected152      );153      if (length === 3) {154        options.secondArgument = 'hint';155        options.secondArgumentColor = _jestMatcherUtils.BOLD_WEIGHT;156        if (propertiesOrHint == null) {157          printedWithType += `\n\nTo provide a hint without properties: toMatchSnapshot('hint')`;158        }159      }160      throw new Error(161        (0, _jestMatcherUtils.matcherErrorMessage)(162          (0, _jestMatcherUtils.matcherHint)(163            matcherName,164            undefined,165            _printSnapshot.PROPERTIES_ARG,166            options167          ),168          `Expected ${(0, _jestMatcherUtils.EXPECTED_COLOR)(169            'properties'170          )} must be an object`,171          printedWithType172        )173      );174    } // Future breaking change: Snapshot hint must be a string175    // if (arguments.length === 3 && typeof hint !== 'string') {}176    properties = propertiesOrHint;177  }178  return _toMatchSnapshot({179    context: this,180    hint,181    isInline: false,182    matcherName,183    properties,184    received185  });186};187const toMatchInlineSnapshot = function (188  received,189  propertiesOrSnapshot,190  inlineSnapshot191) {192  const matcherName = 'toMatchInlineSnapshot';193  let properties;194  const length = arguments.length;195  if (length === 2 && typeof propertiesOrSnapshot === 'string') {196    inlineSnapshot = propertiesOrSnapshot;197  } else if (length >= 2) {198    const options = {199      isNot: this.isNot,200      promise: this.promise201    };202    if (length === 3) {203      options.secondArgument = _printSnapshot.SNAPSHOT_ARG;204      options.secondArgumentColor = _printSnapshot.noColor;205    }206    if (207      typeof propertiesOrSnapshot !== 'object' ||208      propertiesOrSnapshot === null209    ) {210      throw new Error(211        (0, _jestMatcherUtils.matcherErrorMessage)(212          (0, _jestMatcherUtils.matcherHint)(213            matcherName,214            undefined,215            _printSnapshot.PROPERTIES_ARG,216            options217          ),218          `Expected ${(0, _jestMatcherUtils.EXPECTED_COLOR)(219            'properties'220          )} must be an object`,221          (0, _jestMatcherUtils.printWithType)(222            'Expected properties',223            propertiesOrSnapshot,224            _printSnapshot.printExpected225          )226        )227      );228    }229    if (length === 3 && typeof inlineSnapshot !== 'string') {230      throw new Error(231        (0, _jestMatcherUtils.matcherErrorMessage)(232          (0, _jestMatcherUtils.matcherHint)(233            matcherName,234            undefined,235            _printSnapshot.PROPERTIES_ARG,236            options237          ),238          `Inline snapshot must be a string`,239          (0, _jestMatcherUtils.printWithType)(240            'Inline snapshot',241            inlineSnapshot,242            utils.serialize243          )244        )245      );246    }247    properties = propertiesOrSnapshot;248  }249  return _toMatchSnapshot({250    context: this,251    inlineSnapshot:252      inlineSnapshot !== undefined253        ? stripAddedIndentation(inlineSnapshot)254        : undefined,255    isInline: true,256    matcherName,257    properties,258    received259  });260};261const _toMatchSnapshot = config => {262  const {263    context,264    hint,265    inlineSnapshot,266    isInline,267    matcherName,268    properties269  } = config;270  let {received} = config;271  context.dontThrow && context.dontThrow();272  const {currentTestName, isNot, snapshotState} = context;273  if (isNot) {274    throw new Error(275      (0, _jestMatcherUtils.matcherErrorMessage)(276        (0, _printSnapshot.matcherHintFromConfig)(config, false),277        NOT_SNAPSHOT_MATCHERS278      )279    );280  }281  if (snapshotState == null) {282    // Because the state is the problem, this is not a matcher error.283    // Call generic stringify from jest-matcher-utils package284    // because uninitialized snapshot state does not need snapshot serializers.285    throw new Error(286      (0, _printSnapshot.matcherHintFromConfig)(config, false) +287        '\n\n' +288        `Snapshot state must be initialized` +289        '\n\n' +290        (0, _jestMatcherUtils.printWithType)(291          'Snapshot state',292          snapshotState,293          _jestMatcherUtils.stringify294        )295    );296  }297  const fullTestName =298    currentTestName && hint299      ? `${currentTestName}: ${hint}`300      : currentTestName || ''; // future BREAKING change: || hint301  if (typeof properties === 'object') {302    if (typeof received !== 'object' || received === null) {303      throw new Error(304        (0, _jestMatcherUtils.matcherErrorMessage)(305          (0, _printSnapshot.matcherHintFromConfig)(config, false),306          `${(0, _jestMatcherUtils.RECEIVED_COLOR)(307            'received'308          )} value must be an object when the matcher has ${(0,309          _jestMatcherUtils.EXPECTED_COLOR)('properties')}`,310          (0, _jestMatcherUtils.printWithType)(311            'Received',312            received,313            _printSnapshot.printReceived314          )315        )316      );317    }318    const propertyPass = context.equals(received, properties, [319      context.utils.iterableEquality,320      context.utils.subsetEquality321    ]);322    if (!propertyPass) {323      const key = snapshotState.fail(fullTestName, received);324      const matched = /(\d+)$/.exec(key);325      const count = matched === null ? 1 : Number(matched[1]);326      const message = () =>327        (0, _printSnapshot.matcherHintFromConfig)(config, false) +328        '\n\n' +329        printSnapshotName(currentTestName, hint, count) +330        '\n\n' +331        (0, _printSnapshot.printPropertiesAndReceived)(332          properties,333          received,334          snapshotState.expand335        );336      return {337        message,338        name: matcherName,339        pass: false340      };341    } else {342      received = utils.deepMerge(received, properties);343    }344  }345  const result = snapshotState.match({346    error: context.error,347    inlineSnapshot,348    isInline,349    received,350    testName: fullTestName351  });352  const {actual, count, expected, pass} = result;353  if (pass) {354    return {355      message: () => '',356      pass: true357    };358  }359  const message =360    expected === undefined361      ? () =>362          (0, _printSnapshot.matcherHintFromConfig)(config, true) +363          '\n\n' +364          printSnapshotName(currentTestName, hint, count) +365          '\n\n' +366          `New snapshot was ${(0, _jestMatcherUtils.BOLD_WEIGHT)(367            'not written'368          )}. The update flag ` +369          `must be explicitly passed to write a new snapshot.\n\n` +370          `This is likely because this test is run in a continuous integration ` +371          `(CI) environment in which snapshots are not written by default.\n\n` +372          `Received:${actual.includes('\n') ? '\n' : ' '}${(0,373          _printSnapshot.bReceivedColor)(actual)}`374      : () =>375          (0, _printSnapshot.matcherHintFromConfig)(config, true) +376          '\n\n' +377          printSnapshotName(currentTestName, hint, count) +378          '\n\n' +379          (0, _printSnapshot.printSnapshotAndReceived)(380            expected,381            actual,382            received,383            snapshotState.expand384          ); // Passing the actual and expected objects so that a custom reporter385  // could access them, for example in order to display a custom visual diff,386  // or create a different error message387  return {388    actual,389    expected,390    message,391    name: matcherName,392    pass: false393  };394};395const toThrowErrorMatchingSnapshot = function (396  received,397  hint, // because error TS1016 for hint?: string398  fromPromise399) {400  const matcherName = 'toThrowErrorMatchingSnapshot'; // Future breaking change: Snapshot hint must be a string401  // if (hint !== undefined && typeof hint !== string) {}402  return _toThrowErrorMatchingSnapshot(403    {404      context: this,405      hint,406      isInline: false,407      matcherName,408      received409    },410    fromPromise411  );412};413const toThrowErrorMatchingInlineSnapshot = function (414  received,415  inlineSnapshot,416  fromPromise417) {418  const matcherName = 'toThrowErrorMatchingInlineSnapshot';419  if (inlineSnapshot !== undefined && typeof inlineSnapshot !== 'string') {420    const options = {421      expectedColor: _printSnapshot.noColor,422      isNot: this.isNot,423      promise: this.promise424    };425    throw new Error(426      (0, _jestMatcherUtils.matcherErrorMessage)(427        (0, _jestMatcherUtils.matcherHint)(428          matcherName,429          undefined,430          _printSnapshot.SNAPSHOT_ARG,431          options432        ),433        `Inline snapshot must be a string`,434        (0, _jestMatcherUtils.printWithType)(435          'Inline snapshot',436          inlineSnapshot,437          utils.serialize438        )439      )440    );441  }442  return _toThrowErrorMatchingSnapshot(443    {444      context: this,445      inlineSnapshot:446        inlineSnapshot !== undefined447          ? stripAddedIndentation(inlineSnapshot)448          : undefined,449      isInline: true,450      matcherName,451      received452    },453    fromPromise454  );455};456const _toThrowErrorMatchingSnapshot = (config, fromPromise) => {457  const {458    context,459    hint,460    inlineSnapshot,461    isInline,...

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.