Next time you see mysterious failure:
xcodebuild: error: Scheme ... is not currently configured for the test action.
Exited with code 66
check if any of the files have absolute path instead of relative
man sysexits shows:
EX_NOINPUT (66) - An input file (not a system file) did not exist or was not readable.
easiest ways to make a fresh local clone in another directory and run build commands as CircleCI does.
In my case, Xcode 10 decided to make an absolute path in the workspace to the project file.