LibGit2Sharp.Tests.FilterFixture.CanFilterLargeFiles failed

We get always the exception for a blob-file that ... it could not be opened because it is being used by another process. This exception is thrown by the exception handler in filter.cs , Log.Write(LogLevel.Error, "Filter.StreamWriteCallback exception"); It seems that you rely on exclusive file access when using the stream writer (StreamWriteCallback) with the FileShare.None option. But that assumption may not be correct in this case. git_futils_open_ro opens the blob file in question (read mode), and the file is still open while the stream writer in C is starting. We could trace the file handle on Windows. We follow your advice and use the LibGit2TestPath environment variable to be sure that we have complete control over the output test folder, and we observed that Resource Monitor reports the blob file as being locked by the test engine itself. This is our call stack:

Start with LibGit2Sharp.Tests.FilterFixture.CanFilterLargeFiles and inspect filter.cs, especially Filter.StreamWriteCallback and the git_futils_open_ro path described in the report. Reproduce the failure on Windows with LibGit2TestPath set, then trace the file handles and confirm the test completes without the file-in-use exception.