The tests hard-depend on Arrow being built with ZSTD support; in environments where Arrow is compiled without ZSTD, Open() will fail and tests will be flaky. To make tests portable, consider using an always-available configuration (e.g., allow 'no compression' in SpillWriter by skipping codec creation when compression is empty/disabled) and set tests to use that mode.

SpillReader::Close() resets the InputStream without calling Close() on it. If the underlying FileSystem stream holds an OS file descriptor/handle, this can delay resource release (and may break deletion on some platforms). Consider explicitly closing in_stream_ (and propagating/logging any close status) before resetting it.

If fs_->Create(...) succeeds but MakeFileWriter(...) fails, cleanup_guard attempts to delete the path while out_stream_ is still open (and the stream is never closed). This can leak file handles and may prevent deletion on some platforms/filesystems. A concrete fix is to extend the failure cleanup path to close/reset arrow_writer_ (if created) and out_stream_ before deleting the file.

If fs_->Create(...) succeeds but MakeFileWriter(...) fails, cleanup_guard attempts to delete the path while out_stream_ is still open (and the stream is never closed). This can leak file handles and may prevent deletion on some platforms/filesystems. A concrete fix is to extend the failure cleanup path to close/reset arrow_writer_ (if created) and out_stream_ before deleting the file.

SpillChannelManager mutates channels_ without synchronization. Since spill writing/cleanup is often used from multiple threads (writer threads, background cleanup, etc.), AddChannel/DeleteChannel/Reset/GetChannels can race and corrupt the unordered_set. Consider adding a mutex protecting channels_ (and any coupled delete/erase operations) and, if you want to expose channels, returning a copy/snapshot rather than a reference.

These tests instantiate IOManagerImpl directly to access CreateChannel* APIs. If production code obtains an IOManager via IOManager::Create(...), those new channel APIs won't be accessible unless they are part of the IOManager interface. Consider either (mandatory if this is intended as a public/consumable capability) promoting CreateChannel/CreateChannelEnumerator/GetSpillDir to the IOManager interface, or (optional if strictly internal) keeping IOManagerImpl private and testing through IOManager::Create(...).

This helper returns a FileIOChannel::ID, but it uses EXPECT_OK_AND_ASSIGN/EXPECT_OK for operations that are required for the helper to function. If any EXPECT fails, the helper may continue with an uninitialized/invalid writer and cause undefined behavior/crashes. Use ASSERT_OK_AND_ASSIGN/ASSERT_OK in helpers that must succeed (or convert the helper to return Result<FileIOChannel::ID> and propagate failures).