After running unit tests, I used to find two files in the Tests folder for the Derived Data of Xcode - StandardOutputAndStandardError.txt and TestSummaries.plist files. Howe
StandardOutputAndStandardError.txt file, you are looking for, is now located in:
Derived data \your project folder \Logs\Test \.xcresult file \Diagnostics \ \
again and there it is.
For there is also a folder with log from simulator.