Join Free Webinar: Metrics Magic: Boost software quality with data-driven insights!Register Now Join TestMu Conference

How to use matchArity method in Jest

Best JavaScript code snippet using jest

express.js

Source:express.js

1/*2 * Copyright 2020 New Relic Corporation. All rights reserved.3 * SPDX-License-Identifier: Apache-2.04 */5'use strict'6/**7 * Express middleware generates traces where middleware are considered siblings8 * (ended on 'next' invocation) and not nested. Middlware are nested below the9 * routers they are mounted to.10 */11module.exports = function initialize(agent, express, moduleName, shim) {12  if (!express || !express.Router) {13    shim.logger.debug('Could not find Express Router, not instrumenting.')14    return false15  }16  shim.setFramework(shim.EXPRESS)17  shim.setErrorPredicate(function expressErrorPredicate(err) {18    return err !== 'route' && err !== 'router'19  })20  if (express.Router.use) {21    wrapExpress4(shim, express)22  } else {23    wrapExpress3(shim, express)24  }25}26function wrapExpress4(shim, express) {27  // Wrap `use` and `route` which are hung off `Router` directly, not on a28  // prototype.29  shim.wrapMiddlewareMounter(express.Router, 'use', {30    route: shim.FIRST,31    wrapper: wrapMiddleware32  })33  shim.wrapMiddlewareMounter(express.application, 'use', {34    route: shim.FIRST,35    wrapper: wrapMiddleware36  })37  shim.wrap(express.Router, 'route', function wrapRoute(shim, fn) {38    if (!shim.isFunction(fn)) {39      return fn40    }41    return function wrappedRoute() {42      const route = fn.apply(this, arguments)43      // Express should create a new route and layer every time Router#route is44      // called, but just to be on the safe side, make sure we haven't wrapped45      // this already.46      if (!shim.isWrapped(route, 'get')) {47        wrapRouteMethods(shim, route, '')48        const layer = this.stack[this.stack.length - 1]49        // This wraps a 'done' function but not a traditional 'next' function. This allows50        // the route to stay on the stack for middleware nesting after the router.51        // The segment will be automatically ended by the http/https instrumentation.52        shim.recordMiddleware(layer, 'handle', {53          type: shim.ROUTE,54          req: shim.FIRST,55          next: shim.LAST,56          matchArity: true,57          route: route.path58        })59      }60      return route61    }62  })63  shim.wrapMiddlewareMounter(express.Router, 'param', {64    route: shim.FIRST,65    wrapper: function wrapParamware(shim, middleware, fnName, route) {66      return shim.recordParamware(middleware, {67        name: route,68        req: shim.FIRST,69        next: shim.THIRD70      })71    }72  })73  wrapResponse(shim, express.response)74}75function wrapExpress3(shim, express) {76  // In Express 3 the app returned from `express()` is actually a `connect` app77  // which we have no access to before creation. We can not easily wrap the app78  // because there are a lot of methods dangling on it that act on the app itself.79  // Really we just care about apps being used as `request` event listeners on80  // `http.Server` instances so we'll wrap that instead.81  shim.wrapMiddlewareMounter(express.Router.prototype, 'param', {82    route: shim.FIRST,83    wrapper: function wrapParamware(shim, middleware, fnName, route) {84      return shim.recordParamware(middleware, {85        name: route,86        req: shim.FIRST,87        next: shim.THIRD88      })89    }90  })91  shim.wrapMiddlewareMounter(express.Router.prototype, 'use', {92    route: shim.FIRST,93    wrapper: wrapMiddleware94  })95  shim.wrapMiddlewareMounter(express.application, 'use', {96    route: shim.FIRST,97    wrapper: wrapMiddleware98  })99  // NOTE: Do not wrap application route methods in Express 3, they all just100  // forward their arguments to the router.101  wrapRouteMethods(shim, express.Router.prototype, shim.FIRST)102  wrapResponse(shim, express.response)103}104function wrapRouteMethods(shim, route, path) {105  const methods = ['all', 'delete', 'get', 'head', 'opts', 'post', 'put', 'patch']106  shim.wrapMiddlewareMounter(route, methods, { route: path, wrapper: wrapMiddleware })107}108function wrapResponse(shim, response) {109  shim.recordRender(response, 'render', {110    view: shim.FIRST,111    callback: function bindCallback(shim, render, name, segment, args) {112      let cbIdx = shim.normalizeIndex(args.length, shim.LAST)113      if (cbIdx === null) {114        return115      }116      const res = this117      let cb = args[cbIdx]118      if (!shim.isFunction(cb)) {119        ++cbIdx120        cb = function defaultRenderCB(err, str) {121          //Â https://github.com/expressjs/express/blob/4.x/lib/response.js#L961-L962122          if (err) {123            return res.req.next(err)124          }125          res.send(str)126        }127        args.push(cb)128      }129      args[cbIdx] = shim.bindSegment(cb, segment, true)130    }131  })132}133function wrapMiddleware(shim, middleware, name, route) {134  let method = null135  const spec = {136    route: route,137    type: shim.MIDDLEWARE,138    matchArity: true,139    req: shim.FIRST140  }141  if (middleware.lazyrouter) {142    method = 'handle'143    spec.type = shim.APPLICATION144  } else if (middleware.stack) {145    method = 'handle'146    spec.type = shim.ROUTER147  } else if (middleware.length === 4) {148    spec.type = shim.ERRORWARE149    spec.req = shim.SECOND150  }151  // Express apps just pass their middleware through to their router. We do not152  // want to count the same middleware twice, so we check if it has already been153  // wrapped. Express also wraps apps mounted on apps, so we need to check if154  // this middleware is that app wrapper.155  //156  // NOTE: Express did not name its app wrapper until 4.6.0.157  if (shim.isWrapped(middleware, method) || name === 'mounted_app') {158    // Don't double-wrap middleware159    return middleware160  }161  return shim.recordMiddleware(middleware, method, spec)...

index.js

Source:index.js

1'use strict'2var hasOwnProperty = require('../../util/properties').hasOwn3var util = require('util')4/**5 * Enumeration of argument indexes.6 *7 * Anywhere that an argument index is used, one of these or a direct integer8 * value can be used. These are just named constants to improve readability.9 *10 * Each of these values is also exposed directly on the DatastoreShim class as11 * static members.12 *13 * @readonly14 * @memberof Shim.prototype15 * @enum {number}16 */17var ARG_INDEXES = {18  FIRST: 0,19  SECOND: 1,20  THIRD: 2,21  FOURTH: 3,22  LAST: -123}24exports.ARG_INDEXES = ARG_INDEXES25exports.cast = cast26exports.MiddlewareSpec = MiddlewareSpec27exports.RecorderSpec = RecorderSpec28exports.SegmentSpec = SegmentSpec29exports.WrapSpec = WrapSpec30function cast(Class, spec) {31  return spec instanceof Class ? spec : new Class(spec)32}33function WrapSpec(spec) {34  this.wrapper = typeof spec === 'function' ? spec : spec.wrapper35  this.matchArity = hasOwnProperty(spec, 'matchArity') ? spec.matchArity : false36}37function SegmentSpec(spec) {38  this.name       = hasOwnProperty(spec, 'name') ? spec.name : null39  this.recorder   = hasOwnProperty(spec, 'recorder') ? spec.recorder : null40  this.inContext  = hasOwnProperty(spec, 'inContext') ? spec.inContext : null41  this.parent     = hasOwnProperty(spec, 'parent') ? spec.parent : null42  this.parameters = hasOwnProperty(spec, 'parameters') ? spec.parameters : null43  this.internal   = hasOwnProperty(spec, 'internal') ? spec.internal : false44  this.opaque     = hasOwnProperty(spec, 'opaque') ? spec.opaque : false45}46function RecorderSpec(spec) {47  SegmentSpec.call(this, spec)48  this.stream           = hasOwnProperty(spec, 'stream') ? spec.stream : null49  this.promise          = hasOwnProperty(spec, 'promise') ? spec.promise : null50  this.callback         = hasOwnProperty(spec, 'callback') ? spec.callback : null51  this.rowCallback      = hasOwnProperty(spec, 'rowCallback') ? spec.rowCallback : null52  this.after            = hasOwnProperty(spec, 'after') ? spec.after : null53  this.callbackRequired =54    hasOwnProperty(spec, 'callbackRequired') ? spec.callbackRequired : null55}56util.inherits(RecorderSpec, SegmentSpec)57function MiddlewareSpec(spec) {58  RecorderSpec.call(this, spec)59  this.req        = hasOwnProperty(spec, 'req' ) ? spec.req : ARG_INDEXES.FIRST60  this.res        = hasOwnProperty(spec, 'res' ) ? spec.res : ARG_INDEXES.SECOND61  this.next       = hasOwnProperty(spec, 'next' ) ? spec.next : ARG_INDEXES.THIRD62  this.type       = hasOwnProperty(spec, 'type' ) ? spec.type : 'MIDDLEWARE'63  this.route      = hasOwnProperty(spec, 'route' ) ? spec.route : null64  this.params     = hasOwnProperty(spec, 'params') ? spec.params : _defaultGetParams65  this.appendPath = hasOwnProperty(spec, 'appendPath') ? spec.appendPath : true66}67util.inherits(MiddlewareSpec, RecorderSpec)68function _defaultGetParams(shim, fn, name, args, req) {69  return req && req.params...

restify.js

Source:restify.js

1/*2 * Copyright 2020 New Relic Corporation. All rights reserved.3 * SPDX-License-Identifier: Apache-2.04 */5'use strict'6module.exports = function initialize(agent, restify, moduleName, shim) {7  shim.setFramework(shim.RESTIFY)8  shim.setRouteParser(function routeParser(shim, fn, fnName, route) {9    return (route && route.path) || route10  })11  let wrappedServerClass = false12  shim.setErrorPredicate(function restifyErrorPredicate(err) {13    return err instanceof Error14  })15  // Restify extends the core http.ServerResponse object when it's loaded,16  // so these methods are separate from core instrumentation.17  const http = require('http')18  const methods = ['send', 'sendRaw', 'redirect']19  shim.wrap(http.ServerResponse.prototype, methods, function wrapMethod(shim, fn) {20    return function wrappedMethod() {21      const segment = shim.getActiveSegment()22      if (segment) {23        // Freezing the name state prevents transaction names from potentially being24        // manipulated by asynchronous response methods executed as part of res.send()25        // but before `next()` is called.26        segment.transaction.nameState.freeze()27      }28      return fn.apply(this, arguments)29    }30  })31  shim.wrapReturn(restify, 'createServer', wrapCreateServer)32  function wrapCreateServer(shim, fn, fnName, server) {33    // If we have not wrapped the server class, now's the time to do that.34    if (server && !wrappedServerClass) {35      wrappedServerClass = true36      wrapServer(Object.getPrototypeOf(server))37    }38  }39  function wrapServer(serverProto) {40    // These are all the methods for mounting routed middleware.41    const routings = ['del', 'get', 'head', 'opts', 'post', 'put', 'patch']42    shim.wrapMiddlewareMounter(serverProto, routings, {43      route: shim.FIRST,44      endpoint: shim.LAST,45      wrapper: function wrapMiddleware(shim, middleware, name, route) {46        if (shim.isWrapped(middleware)) {47          return middleware48        }49        return shim.recordMiddleware(middleware, {50          matchArity: true,51          route,52          req: shim.FIRST,53          next: shim.LAST54        })55      }56    })57    // These methods do not accept a route, just middleware functions.58    const mounters = ['pre', 'use']59    shim.wrapMiddlewareMounter(serverProto, mounters, function wrapper(shim, middleware) {60      if (shim.isWrapped(middleware)) {61        return middleware62      }63      return shim.recordMiddleware(middleware, {64        matchArity: true,65        req: shim.FIRST,66        next: shim.LAST67      })68    })69  }...

connect.js

Source:connect.js

1/*2 * Copyright 2020 New Relic Corporation. All rights reserved.3 * SPDX-License-Identifier: Apache-2.04 */5'use strict'6module.exports = function initialize(agent, connect, moduleName, shim) {7  if (!connect) {8    shim.logger.debug('Connect not supplied, not instrumenting.')9    return false10  }11  shim.setFramework(shim.CONNECT)12  shim.setRouteParser(function parseRoute(shim, fn, fnName, route) {13    return route14  })15  const proto =16    (connect && connect.HTTPServer && connect.HTTPServer.prototype) || // v117    (connect && connect.proto) // v218  shim.wrapMiddlewareMounter(proto, 'use', {19    route: shim.FIRST,20    endpoint: shim.LAST,21    wrapper: wrapMiddleware22  })23  wrapConnectExport(shim, connect, !proto)24}25function wrapMiddleware(shim, middleware, name, route) {26  const spec = {27    matchArity: true,28    route: route,29    type: shim.MIDDLEWARE,30    next: shim.LAST,31    req: shim.FIRST32  }33  if (middleware.length === 4) {34    spec.type = shim.ERRORWARE35    spec.req = shim.SECOND36  }37  if (shim.isWrapped(middleware)) {38    // In some cases the middleware will be instrumented by a framework39    // that uses connect (e.g. express v3) and we omit the connect40    // instrumentation.41    return middleware42  }43  return shim.recordMiddleware(middleware, spec)44}45function wrapConnectExport(shim, connect, v3) {46  shim.wrapExport(connect, function wrapExport(shim, fn) {47    const wrapper = shim.wrap(fn, function wrapConnect(shim, _fn) {48      return function wrappedConnect() {49        const res = _fn.apply(this, arguments)50        if (v3) {51          shim.wrapMiddlewareMounter(res, 'use', {52            route: shim.FIRST,53            wrapper: wrapMiddleware54          })55        }56        return res57      }58    })59    shim.proxy(fn, Object.keys(fn), wrapper)60    return wrapper61  })...

Blogs

Check out the latest blogs from LambdaTest on this topic:

Is Automated Browser Testing A Must For Modern Web Development?

Cross browser testing is not a new term for someone who is into web development. If you are developing a website or a web application, you would want to run it smoothly on different browsers. But it is not as easy as it sounds!

Best 13 Tools To Test JavaScript Code

Unit and functional testing are the prime ways of verifying the JavaScript code quality. However, a host of tools are available that can also check code before or during its execution in order to test its quality and adherence to coding standards. With each tool having its unique features and advantages contributing to its testing capabilities, you can use the tool that best suits your need for performing JavaScript testing.

Express Testing: Getting Started Quickly With Examples

Before we talk about Express testing, it’s vital to skip fast-forwarding on what Express apps are. Express, a Node.js web application framework, can provide a minimalistic and flexible solution for mobile and web apps. The major use-case served by Express is to offer server-based logic for mobile and web apps when we use it everywhere.

Automated Browser Testing Tutorial: Getting stared with Browser Automation

This article is a part of our Content Hub. For more in-depth resources, check out our content hub on Automation Testing Tutorial.

Why You Should Use Puppeteer For Testing

Over the past decade the world has seen emergence of powerful Javascripts based webapps, while new frameworks evolved. These frameworks challenged issues that had long been associated with crippling the website performance. Interactive UI elements, seamless speed, and impressive styling components, have started co-existing within a website and that also without compromising the speed heavily. CSS and HTML is now injected into JS instead of vice versa because JS is simply more efficient. While the use of these JavaScript frameworks have boosted the performance, it has taken a toll on the testers.

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.