From e1f2c92b191ad70d99234f5dbccb8d2d24c35fa5 Mon Sep 17 00:00:00 2001
From: rbamforth <79797573+rbamforth@users.noreply.github.com>
Date: Sun, 11 Apr 2021 20:57:43 +0100
Subject: [PATCH] Added test that dice rolls are random.

---
 29 Craps/csharp/Craps/Craps/Dice.cs           |  5 +-
 29 Craps/csharp/Craps/Craps/Program.cs        |  3 +-
 .../csharp/Craps/CrapsTester/CrapsTests.cs    | 65 +++++++++++++++++++
 3 files changed, 69 insertions(+), 4 deletions(-)

diff --git a/29 Craps/csharp/Craps/Craps/Dice.cs b/29 Craps/csharp/Craps/Craps/Dice.cs
index 3485f0f6..43186026 100644
--- a/29 Craps/csharp/Craps/Craps/Dice.cs	
+++ b/29 Craps/csharp/Craps/Craps/Dice.cs	
@@ -1,6 +1,5 @@
 using System;
-using System.Collections.Generic;
-using System.Text;
+
 
 namespace Craps
 {
@@ -19,6 +18,6 @@ namespace Craps
             this.sides = sides;
         }
 
-        public int Roll() => rand.Next(1, sides);
+        public int Roll() => rand.Next(1, sides + 1);
     }
 }
diff --git a/29 Craps/csharp/Craps/Craps/Program.cs b/29 Craps/csharp/Craps/Craps/Program.cs
index 17688427..d8109a16 100644
--- a/29 Craps/csharp/Craps/Craps/Program.cs	
+++ b/29 Craps/csharp/Craps/Craps/Program.cs	
@@ -1,12 +1,13 @@
 using System;
 
+
+
 namespace Craps
 {
     class Program
     {
         static void Main(string[] args)
         {
-            Console.WriteLine("Hello World!");
         }
     }
 }
diff --git a/29 Craps/csharp/Craps/CrapsTester/CrapsTests.cs b/29 Craps/csharp/Craps/CrapsTester/CrapsTests.cs
index 9765ba61..2534f21f 100644
--- a/29 Craps/csharp/Craps/CrapsTester/CrapsTests.cs	
+++ b/29 Craps/csharp/Craps/CrapsTester/CrapsTests.cs	
@@ -1,6 +1,8 @@
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 using Craps;
 
+
+
 namespace CrapsTester
 {
     [TestClass]
@@ -27,5 +29,68 @@ namespace CrapsTester
                 Assert.IsTrue(roll >= 1 && roll <= dice.sides);
             }
         }
+
+        [TestMethod]
+        public void DiceRollsAreRandom()
+        {
+            // Roll 600,000 dice and count how many rolls there are for each side.
+
+            var dice = new Dice();
+
+            int numOnes = 0;
+            int numTwos = 0;
+            int numThrees = 0;
+            int numFours = 0;
+            int numFives = 0;
+            int numSixes = 0;
+            int numErrors = 0;
+
+            for (int i = 0; i < 600000; i++)
+            {
+                switch (dice.Roll())
+                {
+                    case 1:
+                        numOnes++;
+                        break;
+
+                    case 2:
+                        numTwos++;
+                        break;
+
+                    case 3:
+                        numThrees++;
+                        break;
+
+                    case 4:
+                        numFours++;
+                        break;
+
+                    case 5:
+                        numFives++;
+                        break;
+
+                    case 6:
+                        numSixes++;
+                        break;
+
+                    default:
+                        numErrors++;
+                        break;
+                }
+            }
+
+            // We'll assume that a variation of 10% in rolls for the different numbers is random enough.
+            // Perfectly random rolling would produce 100000 rolls per side, +/- 5% of this gives the 
+            // range 90000..110000.
+            const int minRolls = 95000;
+            const int maxRolls = 105000;
+            Assert.IsTrue(numOnes >= minRolls && numOnes <= maxRolls);
+            Assert.IsTrue(numTwos >= minRolls && numTwos <= maxRolls);
+            Assert.IsTrue(numThrees >= minRolls && numThrees <= maxRolls);
+            Assert.IsTrue(numFours >= minRolls && numFours <= maxRolls);
+            Assert.IsTrue(numFives >= minRolls && numFives <= maxRolls);
+            Assert.IsTrue(numSixes >= minRolls && numSixes <= maxRolls);
+            Assert.AreEqual(numErrors, 0);
+        }
     }
 }