Investigate data races in unit testing

What's the issue?
We currently have lots of data races in our unit testing. I've looked at a few of the cases and for the most part they are too be expected due to the nature of the tests, however, I'm sure some cases could be avoided to allow more consistent testing.

What's the fix?
We should find/fix known data races using Golangs built in race-detector. Where it's not possible, we should move these test cases into separate Go files which should be built using a build tag which will exclude the tests from race detection. See the documentation for more information.