XCode: Code coverage data generation failed

I've encountered this dreaded problem popping up on an Objective-C project when I attempt to run unit tests. I've tried all of the following (as per various SOF postings):

• Clearing derived data
• Deleting all simulator setups in ~/Library
• Restarting XCode
• Restarting MBP
• Resetting the simulator multiple times
• Changing to a different simulator (even tried ones I've never used)

I checked the console logs and found this:

  26/06/2016 9:20:10.973 PM com.apple.debugserver-@(#)PROGRAM:debugserver  PROJECT:debugserver-350.0.21.9
  [7768]: 1 +0.000000 sec [1e58/1003]: error: ::read ( 3, 0x700000080a40, 1024 ) => -1 err = Bad file descriptor (0x00000009)

I'm not using Cocoapods.

Anyone have any ideas what to try next?