Use fp instead of filename

Tests/test_psdraw.py

@@ -12,13 +12,14 @@ class TestPsDraw(PillowTestCase):
         from PIL import Image
         from PIL import PSDraw
         tempfile = self.tempfile('temp.ps')
+        fp = open(tempfile, "wb")
 
         im = Image.open("Tests/images/hopper.ppm")
         title = "hopper"
         box = (1*72, 2*72, 7*72, 10*72) # in points
 
         # Act
-        ps = PSDraw.PSDraw(tempfile)
+        ps = PSDraw.PSDraw(fp)
         ps.begin_document(title)
 
         # draw the image (75 dpi)
@@ -31,6 +32,7 @@ class TestPsDraw(PillowTestCase):
         ps.text((4*72-w/2, 1*72-h), title)
 
         ps.end_document()
+        fp.close()
 
         # Assert
         # TODO