DuomlyThis article was originally published at: https://www.blog.duomly.com/mocha-vs-jest/
It's hard to believe that it's been only 10 years since Jasmine was created. In that time, the JavaScript testing landscape has changed dramatically.
There are now dozens of options for choosing a testing tool, each with its own advantages and disadvantages. This article will compare two of the most popular options: Mocha and Jest.
1. What are unit tests
Before we get into the details of comparing these tools, let's review what unit tests are. They are short programs that test whether a function works correctly in isolation from other parts of your application.
When you write a program, it's good to verify that each part works as expected before moving on to the next phase. Unit testing can be helpful for this purpose because they are easy to use and run quickly.
There are many industry best practices for writing unit tests. Still, if you're new to them, this guide will give you enough information to get started successfully with Jest or Mocha in 2022!
2. Why you should test your software
Before we get into the details of comparing these tools, let's review some of the advantages of testing your software. First, it makes sure that your code works as expected under various conditions. This is especially important when you're working on a team with other developers because it ensures that everyone's code works together without clashing with each other.
Unit tests can also help you catch errors early in the development process before they have a chance to cause more serious problems. This can save you a lot of time and hassle in the long run. Additionally, well-written unit tests can act as documentation for your code, which can be helpful when you come back to it after a break.
So far, we've only looked at the benefits of unit testing from the perspective of the individual developer. But there are also benefits to be had from a company-wide perspective. Unit tests can help ensure that new code is compatible with existing code. They can make regression test code changes easier and even help identify potential security vulnerabilities.
Overall, there are so many benefits to testing your software that you'd be crazy not to do it!
3. Compare Mocha vs Jest
When it comes to comparing Mocha and Jest, there are a few things to consider.
Mocha is a mature testing tool that has been around for many years. It has a large user base and is well-supported. Jest is a newer tool created by the team at Facebook. It has many of the same features as Mocha and some unique advantages.
Mocha is a little more complicated than Jest when it comes to ease of use. Jest is designed to be simple and straightforward, while Mocha has more options and can be more difficult to learn. However, Mocha can be pretty powerful once you know how to use it.
Jest is also faster than Mocha. It has built-in support for snapshot testing, which means tests are run automatically on each change to the code. This makes it easy to keep your tests up to date as you work.
Mocha has more features out of the box since it is a more mature tool with a larger community of contributors. If you want a specific feature, there's a good chance someone has implemented it already. However, you may need to use a plugin or build your own if that feature isn't already available.
Jest has fewer features than Mocha and doesn't support some valuable things like asynchronous tests. Still, its simplicity is one of its most appealing qualities. If you're looking for a lightweight, straightforward testing tool, Jest might be the better option.
4. Examples of Mocha vs Jest
So far, we've seen some brief examples of how to use Mocha and Jest to accomplish everyday tasks. Now let's look at some comparisons between these tools in greater detail.
Mocha
Supports asynchronous testing with done() callback
Jest
Automatically runs tests after each change to ensure they are up to date. Many users report that this reduces development time.
Mocha
Supports mocking, which lets you avoid slow network requests during tests. Supports BDD syntax. Allows users to define their own assert functions.
Jest
Automatically mocks any modules not explicitly required in the test file, which can save time during development.
5. Choose one option and why it is the best choice for you?
Both Mocha and Jest are great tools that can be used to perform JavaScript testing. Jest takes a more straightforward approach, while Mocha has more features straight out of the box (though some argue that this makes it "bloated").
If you want a tool that is easy to get started with and doesn't require learning a new syntax, Jest might be the better choice.
If you're looking for the most powerful tool available, Mocha might be the better option.
6. Explain how to install, setup, and each tool and how it's used to test JavaScript
Both Mocha and Jest are available on npm, so you can install either tool by running: "npm i Mocha Jest -g"
However, we recommend using a package manager like Yarn, which will give you faster installs. After installing Yarn, run "yarn add mocha jest --dev" to install the latest version of each tool.
Both tools must be initialized to run tests. To initialize Jest, simply create a jest section inside your package.json file with some configuration options under "scripts."
Mocha can be initialized by running "mocha" in the terminal.
Both tools can be run with npm run from your project directory.
For example, to initialize Jest and then run tests, run: "npm run jest"
To initialize Mocha and then run tests, run: "Mocha"
Both tools understand the command line flags -h or --help bring up a help screen.
7. Where you can learn more about Mocha
If you're looking for more information on Mocha, be sure to visit the official documentation.
You can find it at https://mochajs.org/
8. Where you can learn more about Jest
If you're looking for more information on Jest, be sure to visit the official documentation.
You can find it at https://jestjs.io/
If you need help with software testing, please don't hesitate to contact us. We would be happy to help you get started with either Mocha or Jest.
Thank you for reading,
Radek from Duomly
