Raise InvalidOperation if exponents of zeros are clamped during exact

conversion in the Decimal constructor. Exact here refers to the
representation and not to the value (clamping does not change the value).

1 files changed, 24 insertions, 0 deletions

diff --git a/Lib/test/test_decimal.py b/Lib/test/test_decimal.py
index 694b959e21..90f4015549 100644
--- a/Lib/test/test_decimal.py
+++ b/Lib/test/test_decimal.py
@@ -4953,6 +4953,30 @@ class CWhitebox(unittest.TestCase):
         self.assertRaises(ValueError, get_fmt, 12345, invalid_dot, 'g')
         self.assertRaises(ValueError, get_fmt, 12345, invalid_sep, 'g')
 
+    def test_exact_conversion(self):
+        Decimal = C.Decimal
+        localcontext = C.localcontext
+        InvalidOperation = C.InvalidOperation
+
+        with localcontext() as c:
+
+            c.traps[InvalidOperation] = True
+
+            # Clamped
+            x = "0e%d" % sys.maxsize
+            self.assertRaises(InvalidOperation, Decimal, x)
+
+            x = "0e%d" % (-sys.maxsize-1)
+            self.assertRaises(InvalidOperation, Decimal, x)
+
+            # Overflow
+            x = "1e%d" % sys.maxsize
+            self.assertRaises(InvalidOperation, Decimal, x)
+
+            # Underflow
+            x = "1e%d" % (-sys.maxsize-1)
+            self.assertRaises(InvalidOperation, Decimal, x)
+
 
 all_tests = [
   CExplicitConstructionTest, PyExplicitConstructionTest,