Hi, thanks for posting.

NCrunch itself doesn't initiate or hold locks on these files - it has no knowledge of them. The locks are likely being held by your code under test.

There are two likely possibilities here. The first is that the tests are running in parallel and making concurrent use of the log file - see http://www.ncrunch.net/documentation/considerations-and-constraints_concurrent-use-of-test-resources for more information about this problem.

The other possibility is that the tests are not correctly closing the log file when they complete. This probably wouldn't have been an issue when running the tests outside of NCrunch as they would have been run in sequence inside the same process and probably would have used the same file handle. NCrunch, however, will call back into the process multiple times (once for each test batch in the processing queue). See http://www.ncrunch.net/documentation/considerations-and-constraints_test-atomicity for more details on this one.