Every automated test that we write should be deterministic. One of the things we need to do to achieve that is to make our frontend tests independent of the backend. Besides mocking REST API requests, we also need to learn how to mock a WebSocket connection. In this article, we create a simple backend application and […]
One of the most crucial things about writing tests is that they should be deterministic. A particular test should always succeed or always fail. To achieve that, we sometimes need to mock parts of our environment when testing. A good example can be a function that relies on pseudo-random numbers. Besides the above, we also […]
Writing unit and integration tests is a great way to verify the business logic in our code. Unfortunately, it might not be enough to ensure that our application works as expected in a real-life scenario. When hundreds, thousands, or millions of users use our API, it strains it. We simulate the above circumstances through performance […]
Our applications sometimes have features that allow users to choose files from their machine. Also, we might allow the users to download various files. Testing that with Cypress might not seem straightforward at first. In this article, we build a simple React application that allows the users to choose a JSON file from the hard […]
Jest offers a lot of functionalities for mocking functions and spying on them. Unfortunately, there are some pitfalls we need to watch out for. In this article, we explain how spying on functions works. We also explain how and why we should reset our mocks. Creating mock functions The most straightforward way of creating a […]
In the fourth part of this series, we’ve learned the basics of mocking API calls. However, there are often situations where we would like to test various more demanding cases. So, in this article, we implement more advanced examples on how to mock with Jest. Creating a simple React component Let’s start by creating a […]
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In the previous part of this series, we’ve focused on unit tests. This time, we look into integration tests. In this article, we explain their principles and how they differ from unit tests. We write a few of them using Jest to test our services. We also look into the SuperTest library to test our controllers. […]
Cypress has proven to be an appropriate tool for writing E2E tests. In the previous parts of this series, we’ve gone through its basics. That’s a proper moment to take a look at a useful addition: the Gherkin syntax. In this article, we look into its principles and how to make a Cypress Cucumber integration. […]
In the previous part of this series, we’ve learned the basics of the Cypress framework. Although the above knowledge is enough to write our first tests, there is much more to explore. In this article, we dive a bit deeper into the mechanisms of Cypress. By doing so, we can avoid some troubles along the […]
So far, we’ve covered quite a lot of different types of tests. Some of them were unit tests or integration tests, where we tested a specific part of our implementation or components working together. In this article, we look into End-to-End testing and perform it using the Cypress framework. The principles of the End to End (E2E) testing The […]