old_contents: 
  # just load kealib using ctypes
  import sys
  import ctypes
  
  if sys.platform == 'win32':
      kealib = ctypes.CDLL('libkea.dll')
  elif sys.platform == 'darwin':
      kealib = ctypes.CDLL('libkea.dylib')
  else:
      kealib = ctypes.CDLL('libkea.so')
  
  
new_contents: 
  # just load kealib using ctypes
  import os
  import sys
  import ctypes
  
  if sys.platform == 'win32':
      kealib = ctypes.CDLL('libkea.dll')
  elif sys.platform == 'darwin':
      # LD_LIBRARY_PATH not set on OSX
      keapath = os.path.expandvars('$PREFIX/lib/libkea.dylib')
      kealib = ctypes.CDLL(keapath)
  else:
      kealib = ctypes.CDLL('libkea.so')
  
  
subject: fix test for OSX - not set on this OS