By default MsTest puts the test results files in it's current working directory. Teamcity is running MsTest from the buildAgent's temp directory, which is cleared frequently. I want MsTest to run from the buildAgent's workingDirectory.
[12:53:12]: [Step 2/27] Results file: E:\TeamCity\buildAgent\temp\buildTmp\tmpF5DB.tmp.teamcity.trx
I read the this thread http://devnet.jetbrains.net/message/5232885#5232885 but it did not offer a decent solution. If I set my results file manually, subsequent test runs will overwrite existing results.