This is not ideal solution. Adding this will make debugger stop on every test file. When using --inspect-brk, we want to stop only on the first test file.

Could we instead use magic-string's addSourcemapLocation here?

When using --inspect-brk, we want to stop only on the first test file.

Isn't it intended to break each test file? On main, I tested the example like this and it breaks twice on chrome node debugger.

$ pnpm -C examples/basic test -- --inspect-brk --no-file-parallelism 

> @vitest/example-test@ test /home/hiroshi/code/others/vitest/examples/basic
> vitest "--inspect-brk" "--no-file-parallelism"


 DEV  v2.1.3 /home/hiroshi/code/others/vitest/examples/basic

Debugger listening on ws://127.0.0.1:9229/0bdc47a0-344e-4d23-8e04-f1fd797442bf
For help, see: https://nodejs.org/en/docs/inspector
Debugger attached.
 ✓ test/basic.test.ts (3)
Debugger listening on ws://127.0.0.1:9229/30404ff7-fa17-4676-be16-6bbb6ad51d61
For help, see: https://nodejs.org/en/docs/inspector
 ✓ test/basic.test.ts (3)
 ✓ test/suite.test.ts (3)

 Test Files  2 passed (2)
      Tests  6 passed (6)
   Start at  15:43:22
   Duration  14.79s (transform 32ms, setup 0ms, collect 9.25s, tests 7ms, environment 0ms, prepare 5.40s)

It depends on isolate flag I think.

We want to mimic how node --inspect-brk works. We can't simply use node --inspect-brk as it doesn't work with node:worker_threads so we need to build it ourselves like this. 🫠

Right, --poolOptions.forks.singleFork makes it break only once on main.

But, aside from whether we should avoid injecting debugger;, I thought the idea of Vitest's --inspect-brk is to break for each file. Even for child process, actual --inspect-brk wouldn't make sense since it might break in test runner internal code, so choosing a test file as entry makes sense and --inspect-brk was just for user's familiarity.

Yep, that's exactly the idea.

I've been looking into other solutions for a while and can't come up with one. Maybe we should make sure vite-node's injected wrapper contains mapping for debuggers to stop in?

If we want to use debugger; injection instead, we should probably do the same on browser mode.