Jest vs TeamCity: What are the differences?
Some of the features offered by Jest are:
- Familiar Approach: Built on top of the Jasmine test framework, using familiar expect(value).toBe(other) assertions
- Mock by Default: Automatically mocks CommonJS modules returned by require(), making most existing code testable
- Short Feedback Loop: DOM APIs are mocked and tests run in parallel via a small node.js command line utility
On the other hand, TeamCity provides the following key features:
- Automate code analyzing, compiling, and testing processes, with having instant feedback on build progress, problems, and test failures, all in a simple, intuitive web-interface
- Simplified setup: create projects from just a VCS repository URL
- Run multiple builds and tests under different configurations and platforms simultaneously
"Open source" is the top reason why over 24 developers like Jest, while over 52 developers mention "Easy to configure" as the leading cause for choosing TeamCity.
Jest is an open source tool with 26.1K GitHub stars and 3.53K GitHub forks. Here's a link to Jest's open source repository on GitHub.
According to the StackShare community, Jest has a broader approval, being mentioned in 263 company stacks & 150 developers stacks; compared to TeamCity, which is listed in 168 company stacks and 51 developer stacks.
What is Jest?
What is TeamCity?
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I use both mocha and Jest because:
I don't care whether teams use Jest or Mocha. But jest is way too overhyped. Most devs are writing integration tests and think that it's so much better but frankly I don't write integration tests as the way to get both design feedback and confidence when I code. I adhere to the test pyramid, not ice cream cone or the dumb "trophy"
I TDD, so I only ever use the "API" of test frameworks. I don't do a lot of integration tests for TDD and all the bells and whistles Jest provides you from the command-line I just don't need. And I certainly do not care about or touch Jest Snapshots, I despise them
My tests are fast enough because I write isolated tests with TDD, so I don't run into performance issues. Example: I write my tests in a way that I can run 300 tests in literally 1 second with mocha. So the Jest ability to pinpoint and only run those tests which are affected by code changes. I want to run all of them every time when I TDD. It's a different mindset when you TDD
I also mainly code in IntelliJ or WebStorm because I feel the tools in that IDE far surpass VSCode and I also love running the test UI runner in it vs. lousy command-line
I feel both mocha and Jest read just fine in terms of code readability. Jest might have shorter assertion syntax but I don't really care. I just care that I can read the damn test and my tests are written well and my test descriptions, as well as the code itself including constants represent business language, not technical. I care most about BDD, clean code, 4 rules of simple design, and SOLID
I don't like using mock frameworks so no I don't use Jest's Mocking framework. I don't have to mock a lot in my tests due to the nature of how I strive to code...I keep my design simple and modular using principals such as clean code and 4 rules of simple design. If I must mock, I create very simple custom mocks with JS
On the contrary to the belief that integration tests and mount are the way to go (this belief drives me absolutely crazy, especially Dodd's promoting that), I TDD with shallow & enzyme. My tests are simple. My design is driven by my tests and my tests give me quick and useful feedback. I have a course I'm working on coming out soon on TDD with React to show you how to truly test the FE and why the ice cream cone and trophy suck (you're being scammed people). Watch for that here: https://twitter.com/DaveSchinkel/status/1062267649235791873
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Often enough I have to explain my way of going about setting up a CI/CD pipeline with multiple deployment platforms. Since I am a bit tired of yapping the same every single time, I've decided to write it up and share with the world this way, and send people to read it instead ;). I will explain it on "live-example" of how the Rome got built, basing that current methodology exists only of readme.md and wishes of good luck (as it usually is ;)).
It always starts with an app, whatever it may be and reading the readmes available while Vagrant and VirtualBox is installing and updating. Following that is the first hurdle to go over - convert all the instruction/scripts into Ansible playbook(s), and only stopping when doing a clear
vagrant up or
vagrant reload we will have a fully working environment. As our Vagrant environment is now functional, it's time to break it! This is the moment to look for how things can be done better (too rigid/too lose versioning? Sloppy environment setup?) and replace them with the right way to do stuff, one that won't bite us in the backside. This is the point, and the best opportunity, to upcycle the existing way of doing dev environment to produce a proper, production-grade product.
I should probably digress here for a moment and explain why. I firmly believe that the way you deploy production is the same way you should deploy develop, shy of few debugging-friendly setting. This way you avoid the discrepancy between how production work vs how development works, which almost always causes major pains in the back of the neck, and with use of proper tools should mean no more work for the developers. That's why we start with Vagrant as developer boxes should be as easy as
vagrant up, but the meat of our product lies in Ansible which will do meat of the work and can be applied to almost anything: AWS, bare metal, docker, LXC, in open net, behind vpn - you name it.
We must also give proper consideration to monitoring and logging hoovering at this point. My generic answer here is to grab Elasticsearch, Kibana, and Logstash. While for different use cases there may be better solutions, this one is well battle-tested, performs reasonably and is very easy to scale both vertically (within some limits) and horizontally. Logstash rules are easy to write and are well supported in maintenance through Ansible, which as I've mentioned earlier, are at the very core of things, and creating triggers/reports and alerts based on Elastic and Kibana is generally a breeze, including some quite complex aggregations.
If we are happy with the state of the Ansible it's time to move on and put all those roles and playbooks to work. Namely, we need something to manage our CI/CD pipelines. For me, the choice is obvious: TeamCity. It's modern, robust and unlike most of the light-weight alternatives, it's transparent. What I mean by that is that it doesn't tell you how to do things, doesn't limit your ways to deploy, or test, or package for that matter. Instead, it provides a developer-friendly and rich playground for your pipelines. You can do most the same with Jenkins, but it has a quite dated look and feel to it, while also missing some key functionality that must be brought in via plugins (like quality REST API which comes built-in with TeamCity). It also comes with all the common-handy plugins like Slack or Apache Maven integration.
The exact flow between CI and CD varies too greatly from one application to another to describe, so I will outline a few rules that guide me in it: 1. Make build steps as small as possible. This way when something breaks, we know exactly where, without needing to dig and root around. 2. All security credentials besides development environment must be sources from individual Vault instances. Keys to those containers should exist only on the CI/CD box and accessible by a few people (the less the better). This is pretty self-explanatory, as anything besides dev may contain sensitive data and, at times, be public-facing. Because of that appropriate security must be present. TeamCity shines in this department with excellent secrets-management. 3. Every part of the build chain shall consume and produce artifacts. If it creates nothing, it likely shouldn't be its own build. This way if any issue shows up with any environment or version, all developer has to do it is grab appropriate artifacts to reproduce the issue locally. 4. Deployment builds should be directly tied to specific Git branches/tags. This enables much easier tracking of what caused an issue, including automated identifying and tagging the author (nothing like automated regression testing!).
Speaking of deployments, I generally try to keep it simple but also with a close eye on the wallet. Because of that, I am more than happy with AWS or another cloud provider, but also constantly peeking at the loads and do we get the value of what we are paying for. Often enough the pattern of use is not constantly erratic, but rather has a firm baseline which could be migrated away from the cloud and into bare metal boxes. That is another part where this approach strongly triumphs over the common Docker and CircleCI setup, where you are very much tied in to use cloud providers and getting out is expensive. Here to embrace bare-metal hosting all you need is a help of some container-based self-hosting software, my personal preference is with Proxmox and LXC. Following that all you must write are ansible scripts to manage hardware of Proxmox, similar way as you do for Amazon EC2 (ansible supports both greatly) and you are good to go. One does not exclude another, quite the opposite, as they can live in great synergy and cut your costs dramatically (the heavier your base load, the bigger the savings) while providing production-grade resiliency.
We use Jest because when we rebooted our "front end" stack earlier last year, we need to have a testing solution (we didn't have any front-end tests before that!). Jest is fast and convenient and it has plenty of community support behind it. It let's us run our unit tests with Enzyme and snapshot tests.
This is an area that we are constantly reviewing to see what can be improved, both in terms of developer needs, accuracy, test maintainability, and coverage.
I'm currently exploring using React Storybook to be the record of snapshot tests and using some online services, such as Happo.io and Percy in our CI pipeline.
We used to Mocha for as our primary Node.js test framework. We've now switched to Jest and haven't looked back.
Jest is faster and requires less setup and configuration. The Mocha API and eco-system is vast and verified, but that also brings complexity.
It you want to get in, write tests, execute them and get out, try Jest 😀
I really enjoy using Jest as my testing framework. I also use Enzyme to complement, and both together are amazing. Jest is fast and easy to use, It has all you need together under the same tool, and it's pretty easy to create all kind of test, even asynchronous ones. I was responsible for implant it in our company projects, and it was the best decision for testing.
We use JUnit and Jest to perform the bulk of our automated test scenarios, with additional work with Apache JMeter for performance testing - for example, the Atlassian Data Center compliance testing is performed with JMeter. Jest provides testing for the React interfaces, which make up the backend of our App offerings. JUnit is used for Unit Testing our Server-based Apps. Mocha is another tool we use.
We are in the process of adopting Next.js as our React framework and using Storybook to help build our React components in isolation. This new part of our frontend is written in TypeScript, and we use Emotion for CSS/styling. For delivering data, we use GraphQL and Apollo. Jest, Percy, and Cypress are used for testing.
I'm using Jest for 3 months in a Vue JS project . I need to use a lot of custom search of related topics in jest docs because it's not clear. The examples are very poor too.
TeamCity is our main continuous integration server. It starts creating builds and running tests based on commits that we make in our hosted bitbucket repositories. From there, we have a set of configuraitons that can deploy the built and tested artifacts (web app, batches, db, etc...) to a stage or production server. We still release manually, but we release often, and TeamCity has nice features to help us roll back when things don't work out as planned.
TeamCity builds then copies to each web tier via a powershell script. The steps for each server are:
- Tell HAProxy to take the server out of rotation via a POST
- Delay to let IIS finish current requests (~5 sec)
- Stop the website (via the same PSSession for all the following)
- Robocopy files
- Start the website
- Re-enable in HAProxy via another POST
Jest is my unit-testing tool of choice.
Almost all unit testing suites (Mocha, Jasmine, etc.) are more or less the same.
The main advantage I guess, is that it integrates pretty well with React and Enzyme.
I'm using a selfhosted TC as Referenceplatform, and use travis with another configuration.