Restructure the backup package to distinguish the API functionality better.
Move the fake file helper into the testing package.
Support passing dirnames (with trailing /) to CreateEmptyFile().
Split helpers out of backup.go.
Make the backup sources more distinct.
Add some logging.
Set a uniform prefix for backup test methods.
Switch to the a cohesive Backup() signature.
Replace getMongoConnectionInfo with getDatabaseConnectionInfo.
Make tarball generation more flexible.
Switch to using CreateEmptyFile() on the server-side of backup.
Make sure we clean up empty backup files in the error case.
Add support for saving the backup to the same name that was used on the server.