Bot failing when unit tests included Xcode 7.2

I am having some issues running unit tests as part of my CI

I the tests run fine on both my dev laptop and the server (mac mini) - however when I create a bot in order to automate this process the bot downloads the repo and completes steps 1-9 but then fails with the error message

If I remove the unit test from the Bot the Integration completes successfully.

Other examples of this error I have seen, seem to relate to the appropriate version of the simulator not being available on the server - however the server has all available versions and the tests complete fine if I run the build on xcode on the server - but still fail if I run the bot

Also another SO question pointed to 'Skip install' being set to YES - this is not the case in my unit test target

Any help or suggestions would be appreciate it!