Add method for creating a random array of distinct values.

73_Reverse/csharp/Reverse/Reverse.Tests/Generators/PositiveIntegerGenerator.cs

@@ -0,0 +1,10 @@
+using FsCheck;
+
+namespace Reverse.Tests.Generators
+{
+    public static class PositiveIntegerGenerator
+    {
+        public static Arbitrary<int> Generate() =>
+            Arb.Default.Int32().Filter(x => x > 0);
+    }
+}

73_Reverse/csharp/Reverse/Reverse.Tests/Reverse.Tests.csproj

@@ -7,6 +7,7 @@
   </PropertyGroup>
 
   <ItemGroup>
+    <PackageReference Include="FsCheck.Xunit" Version="2.16.4" />
     <PackageReference Include="Microsoft.NET.Test.Sdk" Version="16.9.4" />
     <PackageReference Include="xunit" Version="2.4.1" />
     <PackageReference Include="xunit.runner.visualstudio" Version="2.4.3">

73_Reverse/csharp/Reverse/Reverse.Tests/ReverserTests.cs

@@ -1,3 +1,5 @@
+using FsCheck.Xunit;
+using Reverse.Tests.Generators;
 using System.Linq;
 using Xunit;
 
@@ -48,6 +50,34 @@ namespace Reverse.Tests
 
             Assert.True(input.SequenceEqual(output));
         }
+
+        [Property(Arbitrary = new[] { typeof(PositiveIntegerGenerator) })]
+        public void CreateRandomArray_ReturnsRandomArrayOfSpecifiedLength()
+        {
+            var result = Reverser.CreateRandomArray(5);
+
+            Assert.Equal(5, result.Length);
+        }
+
+        [Property(Arbitrary = new[] { typeof(PositiveIntegerGenerator) })]
+        public void CreateRandomArray_MaxElementValueIsEqualToSize(int size)
+        {
+            var result = Reverser.CreateRandomArray(size);
+
+            Assert.Equal(size, result.Max());
+        }
+
+        [Property(Arbitrary = new[] { typeof(PositiveIntegerGenerator) })]
+        public void CreateRandomArray_ReturnsRandomArrayWithDistinctElements(int size)
+        {
+            var array = Reverser.CreateRandomArray(size);
+
+            var arrayGroup = array.GroupBy(x => x);
+            var duplicateFound = arrayGroup.Any(x => x.Count() > 1);
+
+            Assert.False(duplicateFound);
+        }
+
         [Theory]
         [InlineData(new int[] { 1 })]
         [InlineData(new int[] { 1, 2 })]

73_Reverse/csharp/Reverse/Reverse/Reverser.cs

@@ -1,4 +1,6 @@
-namespace Reverse
+using System;
+
+namespace Reverse
 {
     public class Reverser
     {
@@ -18,6 +20,27 @@
             }
         }
 
+        public static int[] CreateRandomArray(int size)
+        {
+            var array = new int[size];
+            for (int i = 1; i <= size; i++)
+            {
+                array[i - 1] = i;
+            }
+
+            var rnd = new Random();
+
+            for (int i = size; i > 1;)
+            {
+                int k = rnd.Next(i);
+                --i;
+                int temp = array[i];
+                array[i] = array[k];
+                array[k] = temp;
+            }
+            return array;
+        }
+
         public static bool IsArrayInAscendingOrder(int[] array)
         {
             for (int i = 1; i < array.Length; i++)