Codecov

A major aspect of Codecov is the use of long running asynchronous tasks to process large amounts of test coverage data uploaded by our users. Being a Python stack, Celery felt like a natural fit to manage codecov's long running tasks. We rely on Celery to manage all our background queues and asyncronous scheduling. Celery enables us to set timeouts for different tasks which has been instrumental in maintaining our queue in production. Celery also interfaces easily with Redis as a backend store, which allowed it to slot neatly into our existing infrastructure.

We chose TypeScript at Codecov when undergoing a recent rewrite of a legacy front end. Our previous front end was a mishmash of vanilla JavaScript and CoffeeScript , and was expanded upon haphazardly as the need arose. Without a unifying set of paradigms and patterns, the CoffeeScript and JavaScript setup was proving hard to maintain and expand upon by an engineering team. During a move to Vue.js , we decided to also make the move to TypeScript. Integrating TypeScript and Vue.js is fairly well understood at this point, so the setup wasn't all that difficult, and we felt that the benefits of incorporating TypeScript would outweigh the required time to set it up and get our engineering team up to speed.

Choosing to add TypeScript has given us one more layer to rely on to help enforce code quality, good standards, and best practices within our engineering organization. One of the biggest benefits for us as an engineering team has been how well our IDEs and editors (e.g., Visual Studio Code ) integrate with and understand TypeScript . This allows developers to catch many more errors at development time instead of relying on run time. The end result is safer (from a type perspective) code and a more efficient coding experience that helps to catch and remove errors with less developer effort.

We chose Vue.js at Codecov to replace a front end that was based mostly on server side rendered Python templates, and was getting fairly long in the tooth. The move to Vue.js allowed us to take a more component driven approach to our front end, providing greater flexibility and reuse when creating new pages and refactoring old ones. Another bonus was how easily we could integrate Axios with VueJS for making AJAX calls within Vue.js components and their associated vuex stores. We were also able to easily integrate Vue.js with the Jest testing framework, which allowed to provide test coverage for a front end where none previously existed.

The move to Vue.js has allowed us to be more agile in our front end development by further decoupling our front end from our back end. Additionally, by fully embracing a component-driven approach, we're able to more easily isolate and test functionality, leading to a more readible, maintainable, and extensible front end codebase.