Explicitly create top-level directories for tests
Fix directory leak in test_pathname_version
Clear cache after formula install tests
Fix directory leak in test_cleaner
Fix directory leak in test_argv
Clear cache after checksum verification tests
Fix directory leak in test_cleanup
Fix test class name collision
Clear cache after patching tests
Fix directory leaks in formula prefix tests
Fix file leak in lock tests
Remove pin directory when empty
Remove linked kegs directory when empty
Use Keg#uninstall to uninstall kegs
Remove opt link in Keg#uninstall