In the earlier example, we used stub.restore() or mock.restore() to clean up after using them. - sinon es2016, . Uses deep comparison for objects and arrays. How to stub function that returns a promise? Have you used any other methods to stub a function or method while unit testing ? Causes the stub to throw an exception with the name property set to the provided string. Note that you'll need to replace assert.ok with whatever assertion your testing framework has. you need some way of controlling how your collaborating classes are instantiated. stub an object without requiring a method. If we stub out an asynchronous function, we can force it to call a callback right away, making the test synchronous and removing the need of asynchronous test handling. LogRocket tells you the most impactful bugs and UX issues actually impacting users in your applications. Example: var fs = require ('fs') Truce of the burning tree -- how realistic? We usually need Sinon when our code calls a function which is giving us trouble. Add the following code to test/sample.test.js: Alright, I made MailHandler injectable as you suggested, and now I'm able to stub it. Adding mail.handler.module - See below the mailHandler / sendMandrill code: You current approach creates a new sendMandrill for each and every instance created by mailHandler factory. Yields . This is by using Sinons fake XMLHttpRequest functionality. You signed in with another tab or window. UPD If you have no control over mail.handler.module you could either use rewire module that allows to mock entire dependencies or expose MailHandler as a part of your api module to make it injectable. Sinon.js can be used alongside other testing frameworks to stub functions. The sinon.stub() substitutes the real function and returns a stub object that you can configure using methods like callsFake(). But with help from Sinon, testing virtually any kind of code becomes a breeze. In this tutorial, youll learn how to stub a function using sinon. Why was the nose gear of Concorde located so far aft? In Sinons mock object terminology, calling mock.expects('something') creates an expectation. Causes the stub to call the first callback it receives with the provided arguments (if any). Has 90% of ice around Antarctica disappeared in less than a decade? As such, a spy is a good choice whenever the goal of a test is to verify something happened. The second thing of note is that we use this.stub() instead of sinon.stub(). Just imagine it does some kind of a data-saving operation. This happens either using constructor injection, injection methods or proxyquire. It takes an object as its parameter, and sends it via Ajax to a predefined URL. I want to assert, that the value of segmentB starts with 'MPI_'. With Ajax, it could be $.get or XMLHttpRequest. SinonStub.rejects (Showing top 15 results out of 315) Async version of stub.yieldsToOn(property, context, [arg1, arg2, ]). Useful for stubbing jQuery-style fluent APIs. As spies, stubs can be either anonymous, or wrap existing functions. Or, a better approach, we can wrap the test function with sinon.test(). For Node environments, we usually recommend solutions targeting link seams or explicit dependency injection. The following example is yet another test from PubSubJS which shows how to create an anonymous stub that throws an exception when called. A brittle test is a test that easily breaks unintentionally when changing your code. In addition to a stub, were creating a spy in this test. If we use a stub, checking multiple conditions require multiple assertions, which can be a code smell. Your solutions work for me. Like yields, yieldsTo grabs the first matching argument, finds the callback and calls it with the (optional) arguments. Lets say were using store.js to save things into localStorage, and we want to test a function related to that. That's in my answer because the original question specifically asked about it. Its complicated to set up, and makes writing and running unit tests difficult. If you use sinon.test() where possible, you can avoid problems where tests start failing randomly because an earlier test didnt clean up its test-doubles due to an error. calls. First, a spy is essentially a function wrapper: We can get spy functionality quite easily with a custom function like so. Like stub.callsArg(index); but with an additional parameter to pass the this context. Can non-Muslims ride the Haramain high-speed train in Saudi Arabia? Lets see it in action. The result of such a function can be affected by a variety of things in addition to its parameters. Unlike spies and stubs, mocks have assertions built-in. Checking how many times a function was called, Checking what arguments were passed to a function, You can use them to replace problematic pieces of code, You can use them to trigger code paths that wouldnt otherwise trigger such as error handling, You can use them to help test asynchronous code more easily. We pass the stub as its first parameter, because this time we want to verify the stub was called with the correct parameters. If you would like to learn more about either of these, then please consult my previous article: Unit Test Your JavaScript Using Mocha and Chai. Not all functions are part of a class instance. Mocha has many interesting features: Browser support. We can say, the basic use pattern with Sinon is to replace the problematic dependency with a test-double. ts-sinon Prerequisites Installation Object stubs example Interface stubs example Object constructor stub example Sinon methods Packages Dependencies: Dev Dependencies: Tests README.md ts-sinon Book about a good dark lord, think "not Sauron". Go to the root of the project, and create a file called greeter.js and paste the following content on it: JavaScript. How does a fan in a turbofan engine suck air in? If something external affects a test, the test becomes much more complex and could fail randomly. "is there any better way to set appConfig.status property to make true or false?" For the purpose of this tutorial, what save does is irrelevant it could send an Ajax request, or, if this was Node.js code, maybe it would talk directly to the database, but the specifics dont matter. Causes the stub to throw the provided exception object. By clicking Sign up for GitHub, you agree to our terms of service and What capacitance values do you recommend for decoupling capacitors in battery-powered circuits? We can use a mock to help testing it like so: When using mocks, we define the expected calls and their results using a fluent calling style as seen above. We can make use of a stub to trigger an error from the code: Thirdly, stubs can be used to simplify testing asynchronous code. cy.stub() is synchronous and returns a value (the stub) instead of a Promise-like chain-able object. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. Theres also another way of testing Ajax requests in Sinon. What are some tools or methods I can purchase to trace a water leak? document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Testing code with Ajax, networking, timeouts, databases, or other dependencies can be difficult. Here are some examples of other useful assertions provided by Sinon: As with spies, Sinons assertion documentation has all the options available. Once you have project initialized you need to create a library module which provides a method to generate random strings. In this article, we stubbed an HTTP GET request so our test can run without an internet connection. Asking for help, clarification, or responding to other answers. Thanks to all of SitePoints peer reviewers for making SitePoint content the best it can be! Note that in Sinon version 1.5 to version 1.7, multiple calls to the yields* What does meta-philosophy have to say about the (presumably) philosophical work of non professional philosophers? sinon.stub (object, 'method') is the correct way. Eg: if you are using chai-http for integration tests you should call this stub before instanciating server, @MarceloBD That is not true for a spec compliant ES2015+ environment and is not true for CommonJS. And lastly, we removed the save.restore call, as its now being cleaned up automatically. Async version of stub.callsArg(index). Put simply, Sinon allows you to replace the difficult parts of your tests with something that makes testing simple. https://github.com/caiogondim/stubbable-decorator.js, Spying on ESM default export fails/inexplicably blocked, Fix App callCount test by no longer stubbing free-standing function g, Export the users (getCurrentUser) method as part of an object so that, Export api course functions in an object due to TypeScript update, Free standing functions cannot be stubbed, Import FacultyAPI object instead of free-standing function getFaculty, Replace API standalone functions due to TypeScript update, Stand-alone functions cannot be stubbed - MultiYearPlanAPI was added, [feature][plugin-core][commands] Add PasteLink Command, https://github.com/sinonjs/sinon/blob/master/test/es2015/module-support-assessment-test.es6#L53-L58. However, we primarily need test doubles for dealing with functions with side effects. Stubs also have a callCount property that tells you how many times the stub was called. What you need to do is asserting the returned value. rev2023.3.1.43269. We can split functions into two categories: Functions without side effects are simple: the result of such a function is only dependent on its parameters the function always returns the same value given the same parameters. Error: can't redefine non-configurable property "default". They support the full test spy API in addition to methods which can be used to alter the stubs behavior. This makes stubs perfect for a number of tasks, such as: We can create stubs in a similar way to spies. and sometimes the appConfig would not have status value, You are welcome. Using the above approach you would be able to stub prototype properties via sinon and justify calling the constructor with new keyword. It's just a basic example, You can use the same logic for testing your, How do I stub non object function using sinon, The open-source game engine youve been waiting for: Godot (Ep. For example, if you use Ajax or networking, you need to have a server, which responds to your requests. With databases, you need to have a testing database set up with data for your tests. Using sinon.test eliminates this case of cascading failures. If you need to replace a certain function with a stub in all of your tests, consider stubbing it out in a beforeEach hook. responsible for providing a polyfill in environments which do not provide Promise. It also helps us set up the user variable without repeating the values. See also Asynchronous calls. Let's learn how to stub them here. It wouldn't help the original question and won't work for ES Modules. Causes the spy to invoke a callback passed as a property of an object to the spy. For example, the below code stubs out axios.get() for a function that always returns { status: 200 } and asserts that axios.get() was called once. How do I test for an empty JavaScript object? The function used to replace the method on the object.. Importing stubConstructor function: import single function: import { stubConstructor } from "ts-sinon"; import as part of sinon singleton: import * as sinon from "ts-sinon"; const stubConstructor = sinon.stubConstructor; Object constructor stub (stub all methods): without passing predefined args to the constructor: The Promise library can be overwritten using the usingPromise method. It's only after transforming them into something else you might be able to achieve what you want. Because JavaScript is very dynamic, we can take any function and replace it with something else. How can I upload files asynchronously with jQuery? Your code is attempting to stub a function on Sensor, but you have defined the function on Sensor.prototype. By using Sinon, we can take both of these issues (plus many others), and eliminate the complexity. When using ES6 modules: I'm creating the stub of YourClass.get() in a test project. Follow these best practices to avoid common problems with spies, stubs and mocks. Causes the stub to return a Promise which rejects with an exception (Error). Add a custom behavior. Useful for testing sequential interactions. Please note that some processing of your personal data may not require your consent, but you have a right to object to such processing. Async version of stub.callsArgOn(index, context). consecutive calls. What does a search warrant actually look like? The original function can be restored by calling object.method.restore(); (or stub.restore();). If you learn the tricks for using Sinon effectively, you wont need any other tools. If the stub was never called with a function argument, yield throws an error. If the argument at the provided index is not available, a TypeError will be stub.returnsArg(0); causes the stub to return the first argument. We set up some variables to contain the expected data the URL and the parameters. var stub = sinon.stub (object, "method"); Replaces object.method with a stub function. You don't need sinon at all. Similar projects exist for RequireJS. In other words, it is a module. . 542), How Intuit democratizes AI development across teams through reusability, We've added a "Necessary cookies only" option to the cookie consent popup. //Now we can get information about the call, //Now, any time we call the function, the spy logs information about it, //Which we can see by looking at the spy object, //We'll stub $.post so a request is not sent, //We can use a spy as the callback so it's easy to verify, 'should send correct parameters to the expected URL', //We'll set up some variables to contain the expected results, //We can also set up the user we'll save based on the expected data, //Now any calls to thing.otherFunction will call our stub instead, Unit Test Your JavaScript Using Mocha and Chai, Sinon Tutorial: JavaScript Testing with Mocks, Spies & Stubs, my article on Ajax testing with Sinons fake XMLHttpRequest, Rust Tutorial: An Introduction to Rust for JavaScript Devs, GreenSock for Beginners: a Web Animation Tutorial (Part 1), A Beginners Guide to Testing Functional JavaScript, JavaScript Testing Tool Showdown: Sinon.js vs testdouble.js, JavaScript Functional Testing with Nightwatch.js, AngularJS Testing Tips: Testing Directives, You can either install Sinon via npm with, When testing database access, we could replace, Replacing Ajax or other external calls which make tests slow and difficult to write, Triggering different code paths depending on function output. Making statements based on opinion; back them up with references or personal experience. node -r esm main.js) with the CommonJS option mutableNamespace: true. rev2023.3.1.43269. Connect and share knowledge within a single location that is structured and easy to search. This is helpful for testing edge cases, like what happens when an HTTP request fails. The second is for checking integration with the providers manager, and it does the right things when linked together. Spies are the simplest part of Sinon, and other functionality builds on top of them. Create Shared Stubs in beforeEach If you need to replace a certain function with a stub in all of your tests, consider stubbing it out in a beforeEach hook. You should take care when using mocks! Navigate to the project directory and initialize the project. Our earlier example uses Database.save which could prove to be a problem if we dont set up the database before running our tests. Thanks to @loganfsmyth for the tip. Sinon is resolving the request and I am using await mongodb. Async version of stub.yields([arg1, arg2, ]). Start by installing a sinon into the project. For example, if we have some code that uses jQuerys Ajax functionality, testing it is difficult. Once installed you need to require it in the app.js file and write a stub for the lib.js modules method. Normally, testing this would be difficult because of the Ajax call and predefined URL, but if we use a stub, it becomes easy. Here's two ways to check whether a SinonJS stub was called with given arguments. Using Sinons assertions like this gives us a much better error message out of the box. A function with side effects can be defined as a function that depends on something external, such as the state of some object, the current time, a call to a database, or some other mechanism that holds some kind of state. Invokes callbacks passed as a property of an object to the stub. Mocks should be used with care. The most common scenarios with spies involve. Real-life isnt as easy as many testing tutorials make it look. Can the Spiritual Weapon spell be used as cover? Stubbing dependencies is highly dependant on your environment and the implementation. This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply. File is essentially an object with two functions in it. This time we used the sinon.assert.calledWith() assertion. Then you can stub require('./MyFunction').MyFunction and the rest of your code will without change see the stubbed edition. TypeScript Stub Top Level function by Sinon Functions called in a different function are not always class members. What are examples of software that may be seriously affected by a time jump? What you need to do is asserting the returned value. Solution 1 Api.get is async function and it returns a promise, so to emulate async call in test you need to call resolves function not returns: Causes the stub to return a Promise which resolves to the provided value. Stubbing individual methods tests intent more precisely and is less susceptible to unexpected behavior as the objects code evolves. I made this module to more easily stub modules https://github.com/caiogondim/stubbable-decorator.js, I was just playing with Sinon and found simple solution which seem to be working - just add 'arguments' as a second argument, @harryi3t That didn't work for me, using ES Modules. One of the biggest stumbling blocks when writing unit tests is what to do when you have code thats non-trivial. If you want to change how a function behaves, you need a stub. In other words, we can say that we need test-doubles when the function has side effects. mocha --register gets you a long way. The most important thing to remember is to make use of sinon.test otherwise, cascading failures can be a big source of frustration. Causes the stub to throw the exception returned by the function. Making statements based on opinion; back them up with references or personal experience. Stubs can be used to replace problematic code, i.e. Sinon.js . This can be fixed by changing sinon.config somewhere in your test code or in a configuration file loaded with your tests: sinon.config controls the default behavior of some functions like sinon.test. Mocks are a different approach to stubs. You should actually call it w/o new let mh = mailHandler() or even better rename it to createMailHandler to avoid misuse. After some investigation we found the following: the stub replaces references to function in the object which is exported from myModule. Before we carry on and talk about stubs, lets take a quick detour and look at Sinons assertions. A similar approach can be used in nearly any situation involving code that is otherwise hard to test. To learn more, see our tips on writing great answers. After each test inside the suite, restore the sandbox sinon.stub (obj) should work even if obj happens to be a function #1967 Closed nikoremi97 mentioned this issue on May 3, 2019 Stubbing default exported functions #1623 Enriqe mentioned this issue Tooltip click analytics ampproject/amphtml#24640 bunysae mentioned this issue Add tests for the config Find centralized, trusted content and collaborate around the technologies you use most. Causes the stub to return a Promise which resolves to the provided value. Any test-doubles you create using sandboxing are cleaned up automatically. This introduced a breaking change due to the sandbox implementation not supporting property overrides. With the stub() function, you can swap out a function for a fake version of that function with pre-determined behavior. Launching the CI/CD and R Collectives and community editing features for How do I get the path to the current script with Node.js? You need to run a server and make sure it gives the exact response needed for your test. Stubs are functions or programs that affect the behavior of components or modules. Not the answer you're looking for? What can a lawyer do if the client wants him to be aquitted of everything despite serious evidence? For example, a spy can tell us how many times a function was called, what arguments each call had, what values were returned, what errors were thrown, etc. Thanks for contributing an answer to Stack Overflow! To subscribe to this RSS feed, copy and paste this URL into your RSS reader. Like yield, but with an explicit argument number specifying which callback to call. With the stub () function, you can swap out a function for a fake version of that function with pre-determined behavior. We can create anonymous stubs as with spies, but stubs become really useful when you use them to replace existing functions. onCall can be combined with all of the behavior defining methods in this section. Connect and share knowledge within a single location that is structured and easy to search. . But using the restore() function directly is problematic. The text was updated successfully, but these errors were encountered: For npm you can use https://github.com/thlorenz/proxyquire or similar. The name of the method on the object to be wrapped.. replacerFn (Function). After the installation is completed, we're going to create a function to test. All of this means that writing and running tests is harder, because you need to do extra work to prepare and set up an environment where your tests can succeed. Browse other questions tagged, Where developers & technologists share private knowledge with coworkers, Reach developers & technologists worldwide. sinon.config controls the default behavior of some functions like sinon.test. Here, we replace the Ajax function with a stub. document.getElementById( "ak_js_2" ).setAttribute( "value", ( new Date() ).getTime() ); Tutorials, interviews, and tips for you to become a well-rounded developer. Object constructor stub example. Lets say it waits one second before doing something. Stubs implement a pre-programmed response. stub.resolvesArg(0); causes the stub to return a Promise which resolves to the Sinon helps eliminate complexity in tests by allowing you to easily create so called test-doubles. Spies have a lot of different properties, which provide different information on how they were used. This is a comment. This is useful to be more expressive in your assertions, where you can access the spy with the same call. For example, all of our tests were using a test-double for Database.save, so we could do the following: Make sure to also add an afterEach and clean up the stub. Note how the stub also implements the spy interface. Sinon stub interface. Node 6.2.2 / . sinon.stub (Sensor, "sample_pressure", function () {return 0}) is essentially the same as this: Sensor ["sample_pressure"] = function () {return 0}; but it is smart enough to see that Sensor ["sample_pressure"] doesn't exist. Create an anonymous stub that throws an error thanks to all of the project are examples of other assertions! Should actually call it w/o new let mh = mailHandler ( ) the. Restore ( ) substitutes the real function and replace it with the provided arguments ( if any ) and. Stubs perfect for a fake version of stub.callsArgOn ( index ) ; Replaces with! Sinon is to make true or false? we carry on and talk about stubs, lets a. Spy API in addition to its parameters functionality quite easily with a function wrapper: can. Unit testing and sometimes the appConfig would not have status value, need! Http request fails code evolves external affects a test is to replace existing functions this URL your... To your requests the user variable sinon stub function without object repeating the values yet another test from PubSubJS which shows how to a. Running our tests for example, if you want to test a function for a number tasks! Method to generate random strings in less than a decade should actually call it w/o let. The text was updated successfully, but stubs become really useful when you have code thats non-trivial can the! Be affected by a variety of things in addition to a stub share knowledge within a single location is. Way of testing Ajax requests in Sinon functions with side effects paste the following: the stub content the it! Of SitePoints peer reviewers for making SitePoint content the best it can be restored by calling (. Top of them replace the Ajax function with a function for a fake version of stub.callsArgOn ( index, )! Manager, and other functionality builds on top of them get the path to the stub to throw the string! Can configure using methods like callsFake ( ) different function are not always class members returned the! Them to replace the Ajax function with pre-determined behavior an HTTP request fails use this.stub ( or! Object that you 'll need to have a callCount property that tells you how many the... Up with references or personal experience testing Ajax requests in Sinon take both of these issues ( plus others... That the value of segmentB starts with & # x27 ; method & ;... How the stub to call the first callback it receives with the provided exception.. Making SitePoint content the best it can be either anonymous, or responding other. Let mh = mailHandler ( ) ; ( or stub.restore ( ) function directly is.... Sinon.Assert.Calledwith ( ) ; ( or stub.restore ( ) or even better rename it to createMailHandler avoid... Technologists worldwide the parameters function wrapper: we can wrap the test with. With & # x27 ; s learn how to create a library which! Call the first matching argument, finds the callback and calls it with something else expressive in applications. The goal of a test that easily breaks unintentionally when changing your code will without change the... Carry on and talk about stubs, lets take a quick detour and look at assertions! And calls it with something else you might be able to stub them here, yieldsTo grabs the first argument... By the function on Sensor.prototype the text was updated successfully, but with an explicit argument number specifying which to... Object that you 'll need to create a file called greeter.js and this! Due to the sandbox implementation not supporting property overrides we need test-doubles when the has! Ride the Haramain high-speed train in Saudi Arabia the spy to invoke a callback passed as a of... Which responds to your requests from myModule something external affects a test is good... Property to make use of sinon.test otherwise, cascading failures can be sinon stub function without object by a variety of things in to! Or mock.restore ( ) or mock.restore ( ) substitutes the real function and returns a stub original can! $.get or XMLHttpRequest which provides a method to generate random strings words, we need... The simplest part of a Promise-like chain-able object redefine non-configurable property `` default '' s learn how stub! Tips on writing great answers make it look the providers manager, and create a file greeter.js. Called in a test, the test becomes much more complex and could fail randomly replace problematic,! Giving us trouble on Sensor, but stubs become really useful when you use Ajax or networking, you need., copy and paste this URL into your RSS reader the constructor with new keyword context. Was updated successfully, but stubs become really useful when you use Ajax or networking, need! ) arguments from myModule write a stub object that you can swap out function! ( object, & quot ; method & quot ; method & quot ; method #. Is yet another test from PubSubJS which shows how to stub a function,! Addition to a stub it receives with the providers manager, and makes writing and running sinon stub function without object difficult! Database set up, and other functionality builds on top of them like yield, stubs... It waits one second before doing something Where developers & technologists worldwide better it... Are welcome more expressive in your assertions, Where you can stub require ( '! Is useful to be a code smell quite easily with a function argument, finds the callback calls... It via Ajax to a predefined URL to your requests now being cleaned up automatically ( stub.restore... Object terminology, calling mock.expects ( 'something ' ).MyFunction and the Google Privacy Policy and Terms of apply! Something happened avoid misuse avoid misuse to other answers clarification, or responding to other answers your framework. And mocks server and make sure it gives the exact response needed for your tests a,! And wo n't work for ES modules logrocket tells you the most important to... Always class members stub ( ) in a different function are not always class members used alongside testing. Us set up with data for your test throw an exception with name... Data the URL and the parameters spy with the ( optional ).... Takes an object as its first parameter, because this time we used stub.restore )! How do I get the path to the sandbox implementation not supporting property overrides a test, test! A test-double one of the method on the object which is exported from myModule is helpful for testing cases. Stumbling blocks when writing unit tests difficult function using Sinon, testing virtually any kind code... 'Something ' ) creates an expectation site is protected by reCAPTCHA and the Google Privacy Policy Terms. Its parameter, and makes writing and running unit tests is what to do is asserting the returned value lastly! However, we removed the save.restore call, as its now being cleaned up automatically function like.... That affect the behavior defining methods in this article, we used stub.restore ( ) assertion stub them.! Something happened as many testing tutorials make it look property to make true or false ''... An additional parameter to pass the this context and paste this URL into RSS. ; s learn how to stub them here and justify calling the constructor with new keyword has all the available. After some investigation we found the following: the stub to return a which! And wo n't work for ES modules is a good choice whenever goal... It can be a problem if we dont set up the database before running our tests sinon stub function without object... The correct parameters yieldsTo grabs the first callback it receives with the name the! As many testing tutorials make it look but you have defined the function testing Ajax in. Any ) appConfig.status property to make true or false? gives the exact response needed for your.! It: JavaScript this makes sinon stub function without object perfect for a number of tasks such! Happens when an HTTP get request so our test can run without an internet connection database. Yieldsto grabs the first callback it receives with the CommonJS option mutableNamespace: true helps... Aquitted of everything despite serious evidence it gives the exact response needed for your tests with something makes. Better error message out of the box easily breaks unintentionally when changing your will. Test function with pre-determined behavior problem if we have some code that is structured and easy to search of. Sinon is to make use of sinon.test otherwise, cascading failures can be used to replace Ajax. Custom function like so object, & # x27 ; MPI_ & # x27 ; method & quot ; ;.: ca n't redefine non-configurable property `` default '' involving code that uses jQuerys Ajax,... Aquitted of everything despite serious evidence non-Muslims ride the Haramain high-speed train in Saudi Arabia in my answer because original. Or programs that affect the behavior defining methods in this tutorial, youll how! A data-saving operation such a function related to that what happens when an HTTP get request so our test run... Susceptible to unexpected behavior as the objects code evolves database set up, and other functionality on! ; ( or stub.restore ( ) to clean up after using them optional ) arguments a smell! Recaptcha and the implementation doubles for dealing with functions with side effects assertions like this gives us much... Really useful when you use Ajax or networking, you can access the spy to invoke a callback as. Connect and share knowledge within a single location that is structured sinon stub function without object easy to search assertions like gives. Is there any better way to set up some variables to contain the expected data the URL and implementation... To function in the app.js file and write a stub ' ) and! Databases, you need to replace assert.ok with whatever assertion your testing framework sinon stub function without object. Instead of sinon.stub ( object, & # x27 ; re going to a.