[darkclad]

Summary

When nyxus cannot open its Arrow IPC output file for writing, featurize(..., output_type="arrowipc") aborts the Python interpreter instead of raising:

arrow/result.cc:27: ValueOrDie called on an error: Unknown error: Uninitialized Result<T>
Fatal Python error: Aborted

ArrowIPCWriter's constructor dropped the Status returned by setup(). After a failed FileOutputStream::Open, writer_ stayed unassigned, and the first write() dereferenced it. ParquetWriter dropped the FileWriter::Open status the same way.

The open can fail when the target is a directory, the location is read-only, or Windows still has the file mapped for a live pyarrow table. On PR #529's Windows wheel jobs, the last case aborted the test run and cut off pytest's failure summary.

Changes

• ParquetWriter and ArrowIPCWriter constructors throw std::runtime_error when setup() fails. The message names the output path and includes Arrow's error.
• WriterFactory::create_writer catches that and returns the message through its existing error slot. Every caller of create_arrow_file already turns that error into a failed run, so:
  • featurize() raises RuntimeError;
  • the CLI exits non-zero instead of terminating.
• ParquetWriter::setup opens the file through ARROW_ASSIGN_OR_RAISE instead of PARQUET_ASSIGN_OR_THROW, so both writers report a failed open the same way.
• ArrowIPCWriter::setup now returns MakeFileWriter's status.

Example of the new error:

RuntimeError: Error occurred during dataset processing: error creating Arrow file: cannot set up the Arrow IPC writer for <dir>/NyxusFeatures.arrow: IOError: Failed to open local file '<dir>/NyxusFeatures.arrow'. Detail: [Windows error 5] Access is denied.

Tests

test	checks	without the fix
TEST_ARROW_IPC_UNOPENABLE_PATH_MECHANICS	create_arrow_file on a path that is a directory returns failure naming the path; the same stream then writes and reads back a file at a writable path	fails: creation reports success
TEST_ARROW_PARQUET_UNOPENABLE_PATH_MECHANICS	same, for Parquet	fails: the exception escapes create_arrow_file
test_arrow_unopenable_path_raises[arrowipc]	featurize() raises RuntimeError naming the file, then writes to a writable path	aborts the interpreter
test_arrow_unopenable_path_raises[parquet]	same, for Parquet	passes (pybind already converted the old Parquet exception)
test_arrow_ipc_mapped_file_raises (Windows only)	the reported case: a live pyarrow table keeps the file mapped, featurize() raises, and the write succeeds once the table is released	aborts the interpreter

A directory at the target path is the unopenable fixture because no platform opens a directory for writing.

Closes PN-279.

[vjaganat90]

LGTM.

Nit, in a file this PR doesn't touch: tests/vetting/not_covered.md still counts the Arrow tests as they were before this PR.

• Line 33: test_arrow_mechanics.h now has 4 test functions, not 2, so the section A total on line 20 becomes 107.
• B.3: the USE_ARROW row should list TEST_ARROW_IPC_UNOPENABLE_PATH_MECHANICS and TEST_ARROW_PARQUET_UNOPENABLE_PATH_MECHANICS, which makes 15 cases.
• B.4: could add that test_arrow_ipc_mapped_file_raises runs on Windows only.

[darkclad]

Diverted Updated the Arrow row, the USE_ARROW cases and the Windows-only note as suggested, but the totals are 113 and 73 rather than 107 and 15, because both headings were already stale before this PR. The section A tables summed to 111, and test_all.cc registers 73 flag-gated cases, so the OMEZARR_SUPPORT row now describes its 61 cases by name pattern. Done in 7c3a149.