If you can use test262's test suite you should be good, it looks like they are referring to Babel's tests for some of the features? example https://github.com/swc-project/swc/pull/86, I just checked really quick though.
In terms of perf, I'm sure rust will be much faster than JS. And this project's main goal is to be a faster version than Babel. I would suggest the perf test would be different though because it's testing code I would consider not to be representative of what Babel actually runs on. Example with the transform test: https://github.com/swc-project/swc/blob/222bdc191fcab7714319... it's a very small file with minimal transforms even necessary at all. And the parser test is for all minified js files, none of which are written in ES6+ https://github.com/swc-project/swc/blob/master/ecmascript/pa.... Currently it's not really test
Read the rest
ing ES6+, just how at a baseline it's much faster to process a ES5 file, so it's possible that it might be even faster.
edit: I will note that Babel does a lot more than what this project is doing currently (plugins, other proposals, ts/flow, sourcemaps, etc) but this is more about what could be so if people are willing to more on this effort in the long run (with funding/support/people) it could be super useful! I'm curious about how that will work when our project has such a struggle with contributors and Babel itself is written in JS. (I work on Babel :D)