Motivation

testCopyFileReplacingExistingFileSucceeds (and testCopySymlinkReplacingExistingSymlinkSucceeds) verify that no .tmp- prefixed files are left behind after a copyItem(replaceExisting: true) call on Linux. However, both tests create their files in the shared system temp directory (e.g. /tmp) and then scan that entire directory for .tmp- files. When other tests run in parallel, their in-flight copyItem(replaceExisting: true) operations leave transient .tmp- files in the same directory, causing spurious failures.

Changes

• Both tests now create a dedicated subdirectory for their files, so the temp file scan only sees files belonging to that specific test.
• Cleanup is handled via addTeardownBlock to ensure the subdirectory is removed even if the test fails early.

Results

The temp file assertions are no longer affected by concurrent test activity or other processes writing to the shared temp directory, eliminating the flakiness.