Update 80_csv.py

tests/80_csv.py

@@ -11,6 +11,10 @@ test("""a,b,c
 1,2,"3"
 """,  [['a', 'b', 'c'], ['1', '2', '3']])
 
+test("""a,b,c
+1,2,"3,,"
+""",  [['a', 'b', 'c'], ['1', '2', '3,,']])
+
 test("""a,b,c
 1,2,'3'
 """,  [['a', 'b', 'c'], ['1', '2', '\'3\'']])