Fix bug in BigDec.FloorCeiling() which gave the wrong answers for

negative numbers. I have decided that this method will floor towards
negative infinity rather than zero to match SMT-LIBv2's to_int function.

1 files changed, 31 insertions, 0 deletions

diff --git a/Source/UnitTests/BasetypesTests/BigDecTests.cs b/Source/UnitTests/BasetypesTests/BigDecTests.cs
index cee80216..4c26a21a 100644
--- a/Source/UnitTests/BasetypesTests/BigDecTests.cs
+++ b/Source/UnitTests/BasetypesTests/BigDecTests.cs
@@ -24,6 +24,37 @@ namespace BasetypesTests
       Assert.AreEqual(-1, v.Exponent);
       Assert.AreEqual(new BigInteger(15.0), v.Mantissa);
     }
+
+        [TestCase("0.0", 0, 0)]
+        [TestCase("5.0", 5, 5)]
+        [TestCase("5.5", 5, 6)]
+        [TestCase("5.9", 5, 6)]
+        [TestCase("15e1", 150, 150)]
+        [TestCase("15e-1", 1, 2)]
+        // Negative values
+        // Note we expect floor to round towards negative infinity
+        // and ceiling to round towards positive infinity
+        [TestCase("-15e-1", -2, -1)]
+        [TestCase("-5.0", -5, -5)]
+        [TestCase("-5e0", -5, -5)]
+        [TestCase("-5e1", -50, -50)]
+        [TestCase("-5e-1", -1, 0)]
+        [TestCase("-5.5", -6, -5)]
+        [TestCase("-5.9", -6, -5)]
+        public void FloorAndCeil(string value, int expectedFloor, int expectedCeiling)
+        {
+            var v = BigDec.FromString(value);
+            if (value.StartsWith ("-"))
+                Assert.IsTrue(v.IsNegative);
+            else
+                Assert.IsTrue(v.IsPositive || v.IsZero);
+
+            BigInteger floor = 0;
+            BigInteger ceiling = 0;
+            v.FloorCeiling(out floor, out ceiling);
+            Assert.AreEqual(new BigInteger(expectedFloor), floor);
+            Assert.AreEqual(new BigInteger(expectedCeiling), ceiling);
+        }
   }
 }