test_runner API doc example invalid #47312

Affected URL(s)

https://nodejs.org/api/test.html

Description of the problem

This might also include some buggy behavior, though that could be down to a bad/deprecated example in the docs.

When attempting to run a test with the given example:

run({ files: [path.resolve('./tests/test.js')] })
  .pipe(process.stdout);

If there's any error in the calling file or the test, you get:

node:internal/streams/writable:315
      throw new ERR_INVALID_ARG_TYPE(
      ^

TypeError [ERR_INVALID_ARG_TYPE]: The "chunk" argument must be of type string or an instance of Buffer or Uint8Array. Received an instance of Object
    at new NodeError (node:internal/errors:399:5)
    at _write (node:internal/streams/writable:315:13)
    at Writable.write (node:internal/streams/writable:337:10)
    at TestsStream.ondata (node:internal/streams/readable:766:22)
    at TestsStream.emit (node:events:512:28)
    at addChunk (node:internal/streams/readable:324:12)
    at readableAddChunk (node:internal/streams/readable:297:9)
    at Readable.push (node:internal/streams/readable:234:10)
    at #tryPush (node:internal/test_runner/tests_stream:69:28)
    at #emit (node:internal/test_runner/tests_stream:64:18) {
  code: 'ERR_INVALID_ARG_TYPE'
}

If there's no errors, then it just hangs with no output.

The same test runs fine with node --test.

Observing the returned TestsStream for the listed events in the docs (['test:start', 'test:pass', 'test:fail', 'test:diagnostic', 'test:coverage']) and printing the resulting objects shows the test running fine.

Also, using a TransformStream and printing the objects also shows the test running fine.

The error that's shown only when there's an actual error in the file (eg. passing a non-existent file to files for run) hints that TestsStream is now Object Mode which I guess can't be piped directly to stdout without transformation of some sort.

However, this error doesn't appear when the tests would run in the other aforementioned cases and node seems to just stop and sit there, it will print a console.log message placed before and after the run call and then just sit there indefinitely, even with a timeout set, a timeout verified working with the other methods.