tests/float: Add tests for round() of inf, nan and large number.

tests/float/builtin_float_round.py

@@ -15,3 +15,10 @@
 # test second arg
 for i in range(-1, 3):
     print(round(1.47, i))
+
+# test inf and nan
+for val in (float('inf'), float('nan')):
+    try:
+        round(val)
+    except (ValueError, OverflowError) as e:
+        print(type(e))

tests/float/builtin_float_round_intbig.py

@@ -0,0 +1,4 @@
+# test round() with floats that return large integers
+
+for x in (-1e25, 1e25):
+    print('%.3g' % round(x))