node js unit test http request

}); var request = new PassThrough(); Like AVA, it doesnt support globals. assertions, mocking/stubbing, etc) are provided by third-party tools. This function takes in a GitHub username and a callback function. Make your website faster and more secure. Worked with hot startups and Nokia amongst other things, and I'm still excited about programming so I also write about it on my site. This module is only available under the node: scheme. We are using the superagent package to make a request to the GitHub API followers endpoint to fetch a users followers. In this article, we considered two approaches to mocking external APIs in a Node.js test suite but only scratched the surface of what is possible using Jest and Nock in this regard. The below code snippet is an example of a test without any assertions. Email [emailprotected], I'm a software developer from Nigeria with a keen interest in web technologies, security, and performance. Personally, I found the functionality of Nock recordings very useful, but the ergonomics of it could be improved upon. However I suggest to return a status of. Lets say youve decided to test your codebase, and youve read that unit and integration tests shouldnt perform I/O. This is why unit tests are important, and especially testing the failure cases! 2. DigitalOcean makes it simple to launch in the cloud and scale up as you grow whether youre running one virtual machine or ten thousand. First, lets define a code coverage report with a practical example from the Microsoft .NET documentation. Here is an example of test with mocha and chai. In case of missing fields we still return a status of 200, this is for simplicity as we are just learning to test our routes. A stub is a test double that lets us define behavior and track usage set return values, parameters, check the call count, etc. I'm currently working on my own products and teaching programming via my website, to optimize your application's performance, Widgets: The building blocks of Flutter apps, Best open source pagination libraries for Vue 3, Understanding sibling combinators in CSS: A complete guide, Mocking the requests with predefined responses, Intercepting the requests and persisting their responses for later use. Your tests will succeed, but your function may fail in production if the external dependency changes and the mock remains based on the old version. assert.deepEqual(result, expected); Lets assume you have a function that calls an external API like the one shown above and yields a JSON response in the following format: Now, well write a test that confirms that the returned posts have a userId that match the value that was passed to the getPost() function. For the POST scenario, we want to ensure the parameters are passed correctly to the http request. But how does this help? Doubt in Arnold's "Mathematical Methods of Classical Mechanics", Chapter 2, What are good reasons to create a city/nation in which a government wouldn't let you leave. Lets create the index.js file in our root directory: Lets go over our script. var expected = { hello: 'world' }; How To Test a Node.js Module with Mocha and Assert This is another very minimal framework. /* If you really need to test HTTP-specific code, and the response from the external API is relatively simple, use Nock, and manually mock out requests. "text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8", // Some code that GETs http://httpbin.org/get. var write = sinon.spy(request, 'write'); The inverse(?) Unit Testing in Node.js: The Basics and a Quick Tutorial - Bright Security Additionally, some APIs require authentication or authorization. path: '/posts', Note: in a real app, you might want to have a test for the callback, but it should go into its own test case. Using Mocks for Testing in JavaScript With Jest - Stack Abuse We created the stub here, not in the api module! First, start the app by running the following command on your terminal, at the projects root folder: If everything works fine, youll see the message: Listening at http://127.0.0.1:3000. Many would argue that its main strength is its flexibility. } Or of course you could make the http://google.com URL configurable, set that to mockServer.url, and mock / instead of http://google.com. Try Mockttp (disclaimer: I'm the maintainer of Mockttp). My recommendation for you would be to learn more about unit testing and automated testing in general. Today, Jest is considered by many to be the best framework for JavaScript testing. With mocking, you can remove any coupling with external dependencies so that they are no longer a constraint to the unit under test. response.end(); Code coverage is a measurement of the amount of code that is run by unit tests either lines, branches, or methods. During the server testing phase, we will need a way to send HTTP requests. However, there are many more frameworks at your disposal. I've recently started learning unit testing and I'm still getting confused with certain aspects of testing. Unit testing controller functions making external HTTP requests in NodeJS. Jasmine is often called a BDD framework, which causes some confusion. Right? Im going to put this file into tests/apiSpec.js. Now, we can run the tests by just running npm test. What do the characters on this CCTV lens mean? }); Node usually makes things simple, so I expected this to be like that too but I soon discovered that this was not the case at all. This can be achieved in the test file: Finally, we use assert to check the values from the spy: We check that the spy was called once with the correct parameters. We define the expected data, create a mock request, tell our stub to return it and call the api. But you can imagine how a real-world app would have more complex business logic. Although a slow test is probably not a big deal on its own, the whole test suite becomes progressively slower and more brittle when you are running many of these tests, which can be affected by connectivity issues and rate limits. First of all, why the server response structured that way? We will use this to contain each individual test, and do some basic setup. It has a particular focus on simplicity and performance. A mocking library such as Sinon will allow us to create test-doubles easily, which can otherwise be time consuming. No problem, lets add handling for the error event. Then, we switched to relying on Nock to prevent access to the real service and mimic the conditions under which our application would be run. simple async support, including promises. Maintained for @forwardemail, @ladjs, @spamscanner, @breejs, @cabinjs, and @lassjs. How to test code that depends on external APIs in Node.js 3. And as it turns out, youre in the best possible place for that, since the Testim blog has many posts on the subject. callback(err); But the core techniques are the same as I use in real production code. Essentially, the test pyramid describes that you should write unit tests , integration tests and end-to-end tests as well. Additionally, you can expand on the importance of early test by reading our posts about the concept of shift-left testing: Once you have a deeper understanding of Node.js unit testing (and unit testing in general), youll be ready to leverage this form of testing in your QA strategy. beforeEach creates a stub to replace http.request, and afterEach restores the original functionality. This test fulfills the requirements of our tests and when we run the tests again with npm test, we should see that they pass. We will look at the use of http next. As you can see, our tests look a bit cleaner. The cURL approach starts from the web server's endpoint and triggers the entire logic path, but we want the unit test to focus on a specific function taking in the request argument. Think of this post as a hello world for unit testing in Node.js. After that, we move to the why, so you can understand whats the value you gain by adopting unit testing. Nock is a robust library can do much more than this, so its a good idea to take a closer look at it and explore more of its functionalities. Next, lets learn about the reasons behind doing Node.js unit testing. Its easy enough to stand up an API server and writing integration tests, but what if you dont want that much overhead or you are trying to test against a third-party API? var data = ''; afterEach(function() { First, we define the expected data that we will use in our test and create a mock response object. Well, the tech world is incredibly competitive. }); But opting out of some of these cookies may have an effect on your browsing experience. Instead of using Nock to mock out the HTTP request, you can now use your mocking library of choice to mock out our own API wrapper. Now, its time to go over the version of the test that uses Nock and the benefits that it gives us when testing. Before wrapping up, we share some final tips on what to do next. New to Testim? All rights reserved. Inside the test function, pass the name of a file to nockBack so that the recorded output is saved there. this.request.returns(request); A spec comprises expectations examining the state of code that you need test. module.exports = { Your unit tests are giving you feedback about your code. req.end(); Michiel is a passionate blockchain developer who loves writing technical content. Lets write a test that addresses the scenario of a string with two numbers: Now, if I run the tests, I get the following output: Now, youd only have to revert the production code back to normal for both tests to pass. A successful http.request will pass the response to the callback. Unit testing is one of the most important types of automated testing. callback(null, JSON.parse(data)); Start by creating a new file in the project folder and naming it calculator.test.js. When you need to test code that sends out HTTP requests, try the following. Thats the obvious definition, but kind of useless if youre not familiar with the concept of unit testing itself, so lets go further. With this in place, you can assign the return value of any method exported by node-fetch to whatever value you want. Find centralized, trusted content and collaborate around the technologies you use most. Updated on September 15, 2020. data += chunk; This is an advantage for us because we want to test the functionality of our code, and not the accessibility of the services it might depend on in order to work. The key things here are beforeEach and afterEach. Your users dont use your apps by interacting with its units in complete isolation. How can we run the test? Because were mocking the requests, it doesnt matter if the API were working with can simulate errors, we can just simulate those bad requests ourselves! response.on('data', function(chunk) { This lets you use the Nock interceptors to intercept actual HTTP traffic, then store the request/response pair in a file, and use that recording for future requests. A fixture includes a prefixed state or set of objects that youll use as a baseline for running tests. I've recently started learning unit testing and I'm still getting confused with certain aspects of testing. }); Without mocking, it may be difficult to diagnose whether a test failed due to our code or dependencies. }); When calling api.post, it should send parameters in the request body. Sometimes the connection to an external API is exactly what you want to test. demo1: Simple Mock network request. var assert = require ('assert'); var sinon = require ('sinon'); var PassThrough = require ('stream'). Unit testing code that depends on external APIs presents a variety of challenges. Your speed may differ but it should be around the same, give or take. var data = ''; Simple mock processing is performed in test/demo1.test.js, and you can try to run it through npm run test:demo1.In fact, a mock operation is performed on the . Testing HTTP Requests in Node.js Using Nock | DigitalOcean I'm going to put this file into tests/apiSpec.js. Nock can be used to mock individual API responses in a way similar to how we used jest.mock() in the previous section. It turns out a bug snuck into the code. src stores the main file where the program's source code is written. To make sure the expected data is written, we need a way to check the function was called. If we had network connectivity issues, such as running the tests while offline, the test would fail, because of the factors that are out of our control, which would make our tests undependable. * DELETE /book/:id to delete a book given its id. Running this test should fail with the following error: Since we have the tests set up and we know what to expect, we can proceed and implement the actual script. That means it comes with all that you need, which means getting started should be easy and quick. This calls for another test double, in this case a spy. this.request.returns(request); In each unit test, the returned value of the unit must equal the expected value. How to unit test NodeJS HTTP requests? | CodeUtopia }. */, //Query the DB and if no errors, send all the books, //If no errors, send them back to the client, //If no errors, send it back to the client, /* Done! The expected response should be placed in a separate file before the test is executed: If you run the test again, it wont call the external API anymore. var request = new PassThrough(); See Testing Event-Driven Functions for information on how to test event-driven functions. From the sample response, we can see that the response body contains an array of user objects in the following format: In our script, we are first making a request to the GitHub API and if no error occurs, we then iterate over each of the user objects and extract the login property username, from each of the users followers. We save the stub into this.request, so we can reference it later. Since the testing community is obsessed with pyramids, here ya go: I would say that the general consensus in NodeJS land is to use nock , which works by patching Nodes native http module. Fast and flexible authoring of AI-powered end-to-end tests built for scale. Well start with the what of Node.js unit testing, explaining the concept of this form of testing. We require the module config to access the configuration file named as the. Lets start with some definitions. Then, the application will display as a result the sum of the numbers entered. Like previously, we define the expected data first. var expected = JSON.stringify(params); Connect and share knowledge within a single location that is structured and easy to search. A unit testing framework is a tool that takes care of what youll need to perform unit testing: There are many test frameworks for JavaScript. Know how to record and playback live HTTP requests to make testing easier. Nock allows us to avoid these challenges by intercepting external HTTP requests and enabling us to return custom responses, making unit testing easier. Run a single test from the editor Click or in the gutter and select Run <test_name> from the list. Having covered the what and why of unit testing, the next big question left for us to tackle is the how. It took some work, but I found a way to make it simple! I prefer Jest, but this pattern is not tied to any specific mocking library. Common frameworks include Mocha, Jest, Jasmine, and Cypress. If thats not the case, then your test will fail. data += chunk; We call api.post, passing in our parameters and an empty callback. Check out our offerings for compute, storage, networking, and managed databases. document.getElementById( "ak_js_3" ).setAttribute( "value", ( new Date() ).getTime() ); Kevin is a Full Stack Web Developer specializing in Python, JavaScript and React. In addition,the amount of maintenance you need to perform on the tests themselves may increase if you overuse mock objects. This is your first Jest unit test on your Node.js application! This way, our tests will not be affected by issues outside of our control. Instead of guessing why problems happen, you can aggregate and report on problematic network requests to quickly understand the root cause. Most often, a code coverage report tells you the following metrics: For Node.js specifically, popular code coverage libraries include: A Node.js unit test consists of three steps. It is mandatory to procure user consent prior to running these cookies on your website. 576), AI/ML Tool examples part 3 - Title-Drafting Assistant, We are graduating the updated button styling for vote arrows. Is there a place where adultery is a crime? }); }, function(response) { Here are the results for the passing test: It takes 2 seconds to run this simple test. It comes out of the box with everything you need, so you can get started as quickly as possible. Using the command line, youll create a new directory, access it and start a new app: After that, youll have a package.json file with the following content: Now, open the content of the folder with your preffered text editor. To set the response which will be returned when we call the GitHub API, well do this: This means that when we call the https://api.github.com/users/octocat/followers route, the response that should be returned has a 200 status code and returns the content in the followersResponse variable as the response body. A stub is a test double that lets us define behavior and track usage set return values, parameters, check the call count, etc. But since then, the tool has gained a lot of traction, being adopted for non-React apps as well. Unit tests are the most simple type of tests and are easy to write. We have now gained 3 things by leveraging recordings: The approach that Ive outlined in this article has worked well for me. We will need the latest stable version of Node.js, v4.4.7 at the time of writing. . Let's begin this article by writing the Node.js module we'd like to test. Its also important to understand the role unit testing plays in a comprehensive testing strategy, and for that you can read our post on the concept known as the test automation pyramid. Ive already shown how you can use Nock to mock out a very basic HTTP request. Try with POSTMAN and check the response. A call to http.request always returns a request, so we tell it to return our mock request. Simple Mocha/Chai test for Nodejs/Express API, Mocking http requests in node using mocha and sinon. Developers can use SuperTest as a standalone library or with JavaScript testing frameworks like Mocha or Jest. The great thing is that you can apply these methods to test other things too MySQL queries, Redis lookups, Ajax calls, TCP sockets the list goes on and on. You should see a result like this: Congrats! Lets start by creating a Node.js application. Donations to freeCodeCamp go toward our education initiatives, and help pay for servers, services, and staff. req.write(JSON.stringify(data)); For each test, Mocha executes: Any "before each" hooks. Moreover, the site that you intend to scrape already has the HTML that you want to process, so lets make use of that! Thanks for learning with the DigitalOcean Community. The assert step generally uses expect statements to make those assertions. Once were inside the folder, we can initialize our Node.js project by running: This will require a few responses from you. mean? var http = require('http'); Give Jani Hartikainen a like if it's helpful. I've used supertest in the past and was very happy with it. Now that you know more about unit testing, what should your next steps be? Jest boasts to be a zero configuration tool. document.getElementById( "ak_js_2" ).setAttribute( "value", ( new Date() ).getTime() ); Tutorials, interviews, and tips for you to become a well-rounded developer. var api = require('../api.js'); Node.js unit testing helps you to guarantee the quality of your product. How do I troubleshoot a zfs dataset that the server when the server can't agree if it's mounted or not? There's some examples in the README that show exactly what you're looking for: https://www.npmjs.com/package/mockttp#get-testing. Related content: Read our guide to unit testing in Javascript In this article: Why Is Unit Testing Important? We create a PassThrough stream for the request as well, but we only need it as a return value. Avoid using assertionless tests. A successful http.request will pass the response to the callback. Doing this helps make the test easier to maintain, as were not using magic values all over the place. We created the stub here, not in the api module! Mocking External HTTP Requests in Node Tests with Nock Why are they valuable? api.post(params, function() { }); This is the part that confuses me a little. How to mock requests for unit testing in Node - freeCodeCamp.org In this case, we want to mock calls to fetch in the getPosts function so that it returns a canned response instead of reaching out to the real API. We also need sinon to stub the http library. // Code we want to make sure handles errors Get better performance for your agency and ecommerce websites with Cloudways managed hosting. Youre comfortable using the command line. Lets look at some code. post: function(data, callback) { Just like real secret agents, a spy will give us information about its target in this case, the write function. We save the stub into this.request, so we can reference it later. You also have the option to opt-out of these cookies. I have a Node.js app where I wanted to unit test some HTTP requests. However, one thing to note is how long the tests take. Ill demonstrate how to go from a test that calls the external API directly to one that removes the external dependency by: To demonstrate testing code that consumes an external API, well use an example that retrieves a series of posts filtered by user ID provided by JSON placeholder. Install Jest and Setup. Run tests with mocha and now they will pass. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); Testing code that depends on external services and APIs, e.g. req.end(); Node API Authentication with JSON Web Tokens and Passport. | Doing so helps make your tests more readable and easier to understand for other developers. The following will not work: import test from 'test'; const test = require ('test'); copy. However, the application returns an error message, and the user isnt able to sign up. var sinon = require('sinon'); The next time the test is run, the recorded fixture will be used. A Guide to Improving Your QA, You have Node.js installed on your machine. it('should pass request error to callback', function(done) { That is tedious and error-prone. If the current suite has a child suite, repeat the steps in 10. for each child suite; each child suite inherits any "before each" and "after each" hooks defined in its parent. Unit testing is a second chance to validate your architecture and code structure. This includes setting the right state, mocking I/O operations, or adding spies to objects. In addition, the earlier detection of bugs also reduces the overall cost of development because you spend less time on bug fixing in a later stage of the project. Does something seem off? We then define a request stream. Mocha is a javascript framework for Node.js which allows Asynchronous testing. For instance, you can start by learning more about unit testing best practices and the differences and similarities between unit testing and integration testing. To simulate an error, we emit one from the test. Advisory boards arent just for executives. Getting Started with Node.js and Mocha - Semaphore Tutorial AVA is a minimalistic test tool, which is highly opinionated and executes test concurrently, which improves performance. path: '/posts/1' node.js - How to test a function that calls an API using Jest? - Stack Lets go ahead and create the first test: This is the initial test that we will start with: Lets go over the test weve just written: We are importing a getUserFollowers function from the index.js file in the root directory of our project. First of all, lets discuss what is Node.js unit testing in the first place. You can either make requests to Mockttp directly, using a localhost URL, or keep making requests to google.com but use Mockttp as a proxy, and then configure whatever responses (or failed connections/timeouts) you'd like to simulate. @zero298 exactly, that's why I'm suggesting to mock http.get with a stub, so that he doesn't rely on whether Google responds with success or error to check the behaviour of the module under test. }); Its simple: the app youll create is based on the String Calculator Kata, a programming exercise created by Roy Osherov. Making statements based on opinion; back them up with references or personal experience. Lets bring all three elements together to create a unit test. When unit testing, you dont want HTTP requests to go out and affect the result. A single test case should ideally have one assertion only. Thats why in this test, we only need to verify request.write is called with the proper value. Is it possible for rockets to exist in a world that is only in the early stages of developing jet aircraft? This would be highly impractical to so. We define the expected data, create a request stream, tell our stub to return it and call the api. With that in mind, lets test do a little bit of manual exploratory testing. First of all, the user has to fill in all their data. Is that an integration test for that? To copy how http.request works, we write a JSON version of our expected data into the response and end it. It helps improve the quality of your code and reduces the amount of time and money you spend on bug fixing. We will follow the test-driven development convention of writing our tests first. This is why unit tests are important, and especially testing the failure cases! The cURL sample command below shows our test settings. }, function(response) { And, we got hint from this post with the below . Learn how to run unit tests against a real HTTP endpoint, Learn how to return different responses to different HTTP endpoints, and. So, lets go to the production code and change it, deliberately adding a defect. By clicking Accept all cookies, you agree Stack Exchange can store cookies on your device and disclose information in accordance with our Cookie Policy. To make testing easy, well use some libraries to help. How to mock network request in Jest - Medium
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