Fix truncation logic

Pulled out of cloud-custodian#135, where I bit off too much.

Author: stefanvanburen

src/celpy/celtypes.py

@@ -190,7 +190,7 @@
 import logging
 import re
 from functools import reduce, wraps
-from math import fsum
+from math import fsum, trunc
 from typing import (
     Any,
     Callable,
@@ -545,7 +545,7 @@ class IntType(int):
     ValueError: overflow
 
     >>> IntType(DoubleType(1.9))
-    IntType(2)
+    IntType(1)
     >>> IntType(DoubleType(-123.456))
     IntType(-123)
     """
@@ -562,7 +562,7 @@ def __new__(
             # Used by protobuf.
             return super().__new__(cls, cast(int, source.get(StringType("value"))))
         elif isinstance(source, (float, DoubleType)):
-            convert = int64(round)
+            convert = int64(trunc)
         elif isinstance(source, TimestampType):
             convert = int64(lambda src: src.timestamp())
         elif isinstance(source, (str, StringType)) and source[:2] in {"0x", "0X"}:
@@ -729,7 +729,7 @@ def __new__(
         if isinstance(source, UintType):
             return source
         elif isinstance(source, (float, DoubleType)):
-            convert = uint64(round)
+            convert = uint64(trunc)
         elif isinstance(source, TimestampType):
             convert = uint64(lambda src: src.timestamp())
         elif isinstance(source, (str, StringType)) and source[:2] in {"0x", "0X"}:

tests/test_celtypes.py

@@ -111,7 +111,7 @@ def test_double_type():
 def test_int_type():
     i_42 = IntType(42)
     i_max = IntType(9223372036854775807)
-    assert IntType(DoubleType(1.9)) == IntType(2)
+    assert IntType(DoubleType(1.9)) == IntType(1)
     assert IntType(DoubleType(-123.456)) == IntType(-123)
     assert IntType(TimestampType("2009-02-13T23:31:30Z")) == 1234567890
     assert IntType("0x2a") == 42
@@ -160,7 +160,7 @@ def test_int_type():
 def test_uint_type():
     u_42 = UintType(42)
     u_max = UintType(18446744073709551615)
-    assert UintType(DoubleType(1.9)) == UintType(2)
+    assert UintType(DoubleType(1.9)) == UintType(1)
     with pytest.raises(ValueError):
         assert UintType(DoubleType(-123.456)) == UintType(-123)
     assert UintType(TimestampType("2009-02-13T23:31:30Z")) == 1234567890

tools/wip.toml

@@ -239,16 +239,7 @@ string_true_uppercase = "@wip"
 timestamp = "@wip"
 
 [conversions.int]
-double_half_neg = "@wip"
-double_half_pos = "@wip"
 double_int_min_range = "@wip"
-double_truncate = "@wip"
-double_truncate_neg = "@wip"
-
-[conversions.uint]
-double_half = "@wip"
-double_truncate = "@wip"
-
 [dynamic.any]
 literal = "@wip"