Profiling TS-based Jest tests - jestjs

Question

I have a Typescript-based React project in which I am running jest tests (also in TS). I can run tests fine but am trying to profile the performance of some which take quite a long time to run. I have tried using Chrome Devtools to attach to the tests, which it does, however it fails due to it being TS and not plain Js. Is there any way I can profile my tests individually to see where the performance issue is occurring? Using VS Code.

Answer 1

Instead of a React project, it was just a regular TypeScript library for me, but I bet this also works for your use-case. I am leaving this here, in case it's usable, or for future me.
The ONLY solution I found that worked was manually setting up the profiler v8-profiler-next.
import v8Profiler from 'v8-profiler-next';
v8Profiler.setGenerateType(1);
const title = 'good-name';
describe('Should be able to generate with inputs', () => {
v8Profiler.startProfiling(title, true);
afterAll(() => {
const profile = v8Profiler.stopProfiling(title);
profile.export(function (error, result: any) {
// if it doesn't have the extension .cpuprofile then
// chrome's profiler tool won't like it.
// examine the profile:
// Navigate to chrome://inspect
// Click Open dedicated DevTools for Node
// Select the profiler tab
// Load your file
fs.writeFileSync(`${title}.cpuprofile`, result);
profile.delete();
});
});
test('....', async () => {
// Add test
});
});
This then gives you the CPU profile as such, which works fine with TypeScript.