xcrun: error: unable to find utility "xctest", not a developer tool or in PATH
Assuming you already have Xcode installed:
Start Xcode, select "Preferences -> Locations". Chances are that your Command Line Tools are not set. Select the suggested Xcode-tools location and you are done.
Additional:
You could check with:
xcode-select -pwhich tools are set, mine showed:
/Library/Developer/CommandLineToolsAfter the location in the preferences was set, it showed:
/Applications/Xcode.app/Contents/Developer(as it should)
Xcode -> Preferences (or command+,)
Locations tab -> Command Line tools section:Select a tool there and you are done.