edit assert_close in sqlutils.py: support negative infinity

Author: Yuto Akutsu

python/pyspark/testing/sqlutils.py

@@ -16,6 +16,7 @@
 #
 
 import datetime
+import math
 import os
 import shutil
 import tempfile
@@ -246,7 +247,7 @@ def function(self, *functions):
     @staticmethod
     def assert_close(a, b):
         c = [j[0] for j in b]
-        diff = [abs(v - c[k]) < 1e-6 if v != math.inf else v == c[k]
+        diff = [abs(v - c[k]) < 1e-6 if not math.isinf(v) else v == c[k]
                 for k, v in enumerate(a)]
         return sum(diff) == len(a)