Handle errors in parallel teardown files

[gaborcsardi]

I also changed the exit status of the subprocesses to 0 (normal exit),
from 1. I didn't find any reason why it was 1, hopefully there
wasn't any. It is a normal exit, so 0 makes more senset to me (now).

Closes #1165.

[claude]

Claude finished @gaborcsardi's task —— View job

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Code Review

• Read modified files to understand changes
• Analyze test failure and its relationship to the changes
• Identify potential bugs or issues
• Provide code review feedback

Key Issues:

1. Test failure appears unrelated to your changes - The test failure shows "R session closed the process connection, killed" but your teardown error collection logic should handle this properly.

2. Exit status change from 1 to 0 - R/parallel.R:319 - This change makes sense for normal teardown exits, but ensure teardown errors still get properly surfaced through the new error collection mechanism.

3. Worker collection fix looks correct - R/parallel.R:330 - The change from collecting connections to collecting workers is correct since you need both the connection (for polling) and the worker object (for reading messages).

The teardown error collection improvement should handle the test failure case better. The failing test might need investigation of whether the teardown error is occurring before your error collection logic can capture it.

Recommendation: Run the specific failing test in isolation to see if the error collection is working as expected, or if there's a race condition in the teardown process.

[gaborcsardi]

Seems like this is not OK:

══ Failed tests ════════════════════════════════════════════════════════════════
── Error ('test-parallel-stdout.R:16:3'): stdout/stderr in parallel code ───────
Error in `queue_teardown(queue)`: At least one parallel worker failed to run teardown
Caused by error:
! R session closed the process connection, killed
Backtrace:
     ▆
  1. ├─utils::capture.output(...) at test-parallel-stdout.R:16:3
  2. │ └─base::withVisible(...elt(i))
  3. ├─base::suppressMessages(...)
  4. │ └─base::withCallingHandlers(...)
  5. └─testthat::test_local(test_path("test-parallel", "stdout"), reporter = "progress")
  6.   └─testthat::test_dir(...) at testthat/R/test-package.R:73:3
  7.     └─testthat:::test_files(...) at testthat/R/test-files.R:88:3
  8.       └─testthat:::test_files_parallel(...) at testthat/R/test-files.R:165:5
  9.         ├─withr (local) `<fn>`() at testthat/R/parallel.R:67:3
 10.         └─testthat:::queue_teardown(queue) at testthat/R/parallel.R:54:3
 11.           └─cli::cli_abort(...) at testthat/R/parallel.R:388:5
 12.             └─rlang::abort(...)

[gaborcsardi]

Another kind of failure:

══ Failed tests ════════════════════════════════════════════════════════════════
── Failure ('test-parallel-crash.R:22:3'): crash ───────────────────────────────
`err` inherits from 'rlang_error'/'error'/'condition' not 'testthat_process_error'.
── Failure ('test-parallel-crash.R:23:3'): crash ───────────────────────────────
err$test_file (`actual`) is not equal to "test-crash-3.R" (`expected`).

`actual` is NULL
`expected` is a character vector ('test-crash-3.R')

[ FAIL 2 | WARN 0 | SKIP 4 | PASS 1221 ]