Workaround for limitations of NamedTemporaryFile on Windows

wrappers/python/tests/TestCharmmFiles.py

@@ -5,6 +5,7 @@ from simtk.openmm import *
 from simtk.unit import *
 import simtk.openmm.app.element as elem
 import math
+import os
 import tempfile
 import warnings
 if sys.version_info >= (3,0):
@@ -337,10 +338,11 @@ class TestCharmmFiles(unittest.TestCase):
         # The following values were computed with CHARMM.
         modeEnergy = {0: 754318.20507, 1: 754318.20507, 2: 908.35224, 3: 59.65279, 4: -241.12856, 5: 39.13169}
         for nbxmod in range(-5, 6):
-            with tempfile.NamedTemporaryFile(suffix='.par', mode='w') as parfile:
+            with tempfile.NamedTemporaryFile(suffix='.par', mode='w', delete=False) as parfile:
                 parfile.write(par.replace('nbxmod  5', 'nbxmod %d' % nbxmod))
-                parfile.flush()
+                parfile.close()
                 params = CharmmParameterSet('systems/charmm22.rtf', parfile.name)
+                os.remove(parfile.name)
             system = self.psf_c.createSystem(params, nonbondedMethod=NoCutoff)
             context = Context(system, VerletIntegrator(1*femtoseconds), Platform.getPlatformByName('Reference'))
             context.setPositions(crd.positions)