This causes ever-growing debris to accumulate in /tmp which is often a ramdisk. One solution would be to take advantage of the fact that DEATH_TESTs already examine stdout, and just look for the lines that start with "Created temporary directory:". Another would be to create a TempDir in the parent process and make the child pass that to TempDir::setTempPath, but that will create the TempDir even for tests that don't need it.