Can't load XCTest for Realm testing

When I build my test target and try to execute Realm tests I"m getting: Symbol not found: _RLMErrorDomain when it tries to load the test bundle. I've add pod 'Realm' to my test target in my Podfile.

I initially was getting the error, Symbol not found _OBJC_CLASS_$_RLMObject but I resolved that from changing my pod file from pod 'Realm/headers' to pod 'Realm'. I found that issue/solution here: http://ift.tt/2agV5E8

I've recently converted over to Realm to replace my CoreData stack based approach. This unit test worked fine for testing the ManagedObject version of my model objects and object adapters.