Jest

ts-jest is a popular package when you try to use typescript with jest. But one issue that is bugging me recently is, that the uncovered lines stat is not correct, my test coverage dropped by 10+%. After googling, nothing useful come up, and after some troubleshooting, I found out that…

You can with the dom-testing-library Recently, I came across an issue where I was unable to trigger a click event on an icon. For a component that looks something like this, <Icon onClick={() => { // do something }} data-testid="icon-test-id" > I was trying to simulate a click in my tests the same way I…

( This article is a translated copy of my old article on my Japanese blog. -> https://komajou.hatenablog.jp/entry/2019/04/02/181246 ) What do you do when you want to force a test to fail in Jest? I assumed that Jest has a method like fail() and searched for how to do that, but apparently they don’t have it. https://stackoverflow.com/questions/42176642/in-jest-how-can-i-make-a-test-fail According to StackOverflow, the following method works

The library csv-parse/sync is used in the code that I was working on for parsing csv files synchronously. It’s working fine in the code but it failed when I ran the unit tests with Jest framework. The similar issue can be found here. This issue can be fixed by specifying…

We all know how important npm registry is for web development. On this blog, we will look into how we can create our own npm packages and publish them in npm registry so that everyone can make a use of your awesome work. There are few requirements that needs to…

Testing your application is great! But sometimes, it’s hard to figure out if everything (relevant) has been covered with tests. Especially when you’re not going down a Test Driven Development path. Jest can collect coverage information for you, showing you where you can improve your test coverage by running it with --coverage : By default, you also get a nice visualisation of the coverage by looking at the report in coverage/lcov-report/index.html

In this article, I’m going to introduce React testing tool called Jest which is designed to test React application. Testing software application is an important. It helps to find out whether the software meets the actual requirements or not. The purpose of testing is to prevent regression. Regression is the…

This article is a continuation of creating the Trading View Lambda Bot. You can read the previous part here. To ensure that everything works correctly, we will write integration tests. For tests, we will use Jest. So, let’s install packages: yarn add -D jest jest-extended ts-jest @types/jest Firstly, we will…

What is JEST? In this day and age, one of the most important tenets of being a software engineer is practicing TDD (or Test Driven Development). TDD is a process in which software requirements are converted into test cases BEFORE the software is fully developed. Why would you want to apply this practice…