Network Requests with Cypress

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Whether you're testing your UI or API, Cypress gives you all the tools needed to work with and manage network requests. This intermediate-level task demonstrates how to use the cy.request and cy.intercept commands to execute, spy on, and stub network requests while testing your application in the browser. Learn how the commands work as well as use cases for each, including best practices for testing and mocking your network requests.

Cecelia Martinez
Cecelia Martinez
33 min
18 Nov, 2021

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Video Summary and Transcription

Cecilia Martinez, a technical account manager at Cypress, discusses network requests in Cypress and demonstrates commands like cydot request and SCI.INTERCEPT. She also explains dynamic matching and aliasing, network stubbing, and the pros and cons of using real server responses versus stubbing. The talk covers logging request responses, testing front-end and backend API, handling list length and DOM traversal, lazy loading, and provides resources for beginners to learn Cypress.

Available in Español

1. Introduction to Network Requests with Cypress

Short description:

Hello, I'm Cecilia Martinez, a technical account manager at Cypress. Today, I'll talk about network requests with Cypress. Cypress is an open-source framework for writing and executing tests in a browser. It provides a graphical user interface with a command log that displays network requests made during tests. You can also interact with network requests using the cydot request and cydot intercept commands. I'll be using code from the Cypress real world app, an open-source payment application, to demonstrate these commands.

Hello, I'm Cecilia Martinez, and I'm a technical account manager at Cypress. And I'm really excited to be here today to talk to you about network requests with Cypress. I've made the slides for the presentation available at the URL on the screen, and you can connect with me on Twitter at Cecilia Creates.

So, for those of you who aren't familiar with Cypress, it is a free open-source framework that allows you to write and execute tests for any application that runs in a browser. Cypress does execute tests against your application inside a real browser. You can see on the screen here a representation of our graphical user interface when you're running your tests locally. So, the application under test is on the right-hand side in the app preview. And then on the left-hand side, we have what's called our command log, which as it sounds like is a log of all the commands that your test code is executing against your application. This gives us some good information about network requests that are happening inside your application as the tests are progressing. So, you can view network requests as they occur in the command log. Here in the screenshot, we can see that after our test code has clicked an element that a post request occurred. We can see the status code, we can see the endpoint, as well as how we may or may not be interacting with that request via our test code. We can also click on any request in the command log to output it to the console. This gives you some additional helpful information like request headers, response body, which can be useful when you're troubleshooting or debugging failed tests, or trying to better understand what's happening with the network requests from your application.

So, in addition to viewing network requests within the Cypress test runner, you can also interact with them. So, we're going to be talking about two commands today that allow you to work with network requests within your Cypress tests. The first is cydot request, which executes HTTP requests. And the second is cydot intercept, which allows you to interact with network requests. For demonstration purposes today, I'll be using some code from the Cypress real world app. The Cypress real world app is a great resource. It was developed by our Developer Experience team. It's a full stack React application that showcases best practices, use cases, and then essentially all the different things that you can do with Cypress. So, it is open source. So, if you go to the github link on the screen, you can view the source code as well as a full suite of UI and API tests for the application. It's a Venmo-style payment application. So, you're dealing with things like users, transactions, bank accounts, and a lot of very familiar UI components.

2. Introduction to cydot request

Short description:

cydot request is a command in Cypress that allows you to send HTTP requests from your test code. It's commonly used for API testing, where you can validate responses from server endpoints. You can also use it to retrieve, create, or update data for testing purposes. Additionally, you can use it to validate endpoints before proceeding with your test.

All right. So, we can get started with cydot request. So, as I mentioned, cydot request sends an HTTP request from your test code. This is separate from the functionality of your application. It's similar to how you may send an HTTP request from a cURL or postman. So, the syntax is cydot request. At minimum, you do have to pass through the URL of the endpoint where you're making the request. You can also pass through the method, a specified body, and then additional options for the request.

So, why would you use cydot request? The most popular use case is actually for API testing. Cypress, while it's mostly known for UI and end-to-end tests, you can also use the cydot request command, along with the same assertion language that you're familiar with, in order to validate responses coming back from your server endpoints. So, in the example here, this is coming directly from the API test suite in our Cypress real-world app. We are validating a GET request to our bank account's endpoint, and the block for the test is that it gets a list of bank accounts for a user. So, in this case, we're using cydot request on line 4 in order to make a GET request to that endpoint. And then, we are grabbing the response and we're making assertions against it. So, we're expecting that that response status will equal 200. And we're expecting that the response body will contain the user ID in the results. So, again, you can leverage the same Cypress syntax that you're used to for API testing alongside your UI test suite. You can also use it to retrieve, create, or update data for testing.

So, test data management is a really popular topic when it comes to testing, especially when you're doing end-to-end tests. And so, if you need to retrieve data from an endpoint, such as a username or password to log in, or if you need to create a transaction or create something in your application in order to test it, rather than doing it programmatically, you can use a signed request call in order to do that via your API. You can also use it to validate endpoints before proceeding with your test. So if you have maybe like an unreliable endpoint or backend that might be slower or down, or if you're using a third-party service or micro service and you just want to ensure that everything is all set before proceeding with your test, you can fire off a sign-out request, validate that its response status is 200, that it's good to go, and then go ahead and proceed with the test that requires that endpoint.

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