react-codemod VS ava

You can convert the “easy” render-only class components to function components using the pure-component codemod.

Developer Experience - There are a number of tools that improves the development experience with React. React Developer Tools is a browser extension that allows you to inspect your component, view and manipulate its props and state. Hot reloading with webpack allows you to view changes to your code in your browser, without you having to refresh the browser. Front end development involves a lot of tweaking code, saving and then refreshing the browser. Hot reloading helps you by eliminating the last step. When there are library updates, Facebook provides codemod scripts to help you migrate your code to the new APIs. This makes the upgrading process relatively pain-free. Kudos to the Facebook team for their dedication in making the development experience with React great.

Like most popular libraries, e.g. React, Next.js and more, which provide codemods to help move their huge user base across versions, we needed a bespoke and fairly simple CLI wrapper of jscodeshift, that would provide a means of publishing, downloading and running codemods. So we created a custom 'codemod-cli', our first piece of internal codemod infrastructure.

If you'd like to migrate them, the React team maintains some awesome codemods:

https://github.com/reactjs/react-codemod

Codemods - providing automated tooling to change old patterns to new ones can go a long way in helping drive adoption of the new version. The most notable example of doing this is react-codemod (many other examples exist)

Sometimes you need to migrate from one version of a library to another, for example, when React has updated to version 15.5 the PropTypes has moved to different package and the react-developers provides codemod for migration.

Can you point me towards examples of the usage of AST rewriting tools that are actively being used by open-source library maintainers in other ecosystems to help their consumers do upgrades in large code-bases (e.g. I can see that `clang` has AST tooling, but I don't see examples online of this being widely used: https://devblogs.microsoft.com/cppblog/exploring-clang-tooli...).

Within the JavaScript ecosystem this is quite popular (1. https://github.com/reactjs/react-codemod; 2. https://github.com/mui-org/material-ui/tree/HEAD/packages/ma... 3. https://github.com/emotion-js/emotion/tree/main/packages/esl... etc.) Teams that maintain huge codebases have tooling to safely automate their upgrades and the best library maintainers provide their consumers with these AST transformations.

  > Don't tell that to anyone who uses

Agree. I know js has a similar tool, jscodeshift. https://github.com/reactjs/react-codemod and https://github.com/cpojer/js-codemod/tree/master/transforms have some ideas for js.

We use Jest Framework for testing. Jest is not a dogma, and, of course, in its place can be any other test runner, such as Mocha or Ava. Let's focus on tests. I'll provide a short example because I don’t want to waste your time. You can find the full version here. It's crucial to read the comments in the code below. Let's go!

> In the popular jest test runner, each test file is executed in its own child process.

Is that confirmed?

I've been following this issue:

https://github.com/jestjs/jest/issues/6957

And what Jest actually does is still kind of muddy.

In contrast to that, other test runners like AVA have a clear description what happens when:

https://github.com/avajs/ava/blob/main/docs/01-writing-tests...

I've been looking at using japa or ava for web server testing but was curious what others were using and why.

Continued work on the test suite. Implementing AVA, with snapshotting. Making a lot of effort to have the snapshot directory structure match the test262 test directory structure by generating AVA test files.

You might want to give ava a spin:

https://github.com/avajs/ava/

It has a TAP reporter, but more importantly, as opposed to the more popular solutions, like Jest, the way it achieves parallelism is explained in the docs and won't change anytime soon, thus preventing wonky, hard to debug errors which occur when this part is abstracted away.

I switched to ava for that reason and have been very happy with it. But vitest looks nice, too. Thanks for the pointer.

Runs unit tests using AVA.

Last but not least important are ava, uvu and tape; they are a really light and fast test runners.

I've had some good experiences with Ava + Sinon. I've personally disliked Jest because it seemed to do some weird trickery in the background that prevented me from using ES modules.

Ava for a simpler environment than Jest, which I usually use. I need to check how to mock ESM with it, though.