transforms: facade test

Signed-off-by: Christoph Ruegg <git@cdrnet.ch>

src/UnitTests/IntegralTransformsTests/DftTest.cs

@@ -38,7 +38,7 @@ namespace MathNet.Numerics.UnitTests.IntegralTransformsTests
     [TestFixture]
     public class DftTest
     {
-        private static Random _random = new Random();
+        private static readonly Random _random = new Random();
 
         private static Complex[] ProvideSamples(int count)
         {
@@ -245,6 +245,30 @@ namespace MathNet.Numerics.UnitTests.IntegralTransformsTests
             AssertHelpers.AlmostEqualList(samples, work, 1e-12);
         }
 
+        [Test]
+        public void DefaultTransformIsReversible()
+        {
+            var samples = ProvideSamples(0x7FFF);
+            var work = new Complex[samples.Length];
+            samples.CopyTo(work, 0);
+
+            Transform.FourierForward(work);
+
+            Assert.IsFalse(work.AlmostEqualListWithError(samples, 1e-12));
+
+            Transform.FourierInverse(work);
+
+            AssertHelpers.AlmostEqualList(samples, work, 1e-12);
+
+            Transform.FourierInverse(work, FourierOptions.Default);
+
+            Assert.IsFalse(work.AlmostEqualListWithError(samples, 1e-12));
+
+            Transform.FourierForward(work, FourierOptions.Default);
+
+            AssertHelpers.AlmostEqualList(samples, work, 1e-12);
+        }
+
         [Test]
         public void TransformSatisfiesParsevalsTheorem()
         {

src/UnitTests/IntegralTransformsTests/DhtTest.cs

@@ -26,21 +26,17 @@
 // OTHER DEALINGS IN THE SOFTWARE.
 // </copyright>
 
-using System.Collections.Generic;
-
 namespace MathNet.Numerics.UnitTests.IntegralTransformsTests
 {
     using System;
-    using System.Linq;
     using MbUnit.Framework;
     using IntegralTransforms;
     using IntegralTransforms.Algorithms;
-    using Statistics;
 
     [TestFixture]
     public class DhtTest
     {
-        private static Random _random = new Random();
+        private static readonly Random _random = new Random();
 
         private static double[] ProvideSamples(int count)
         {