Merge pull request #169 from commit-n-run/patch-1

RegistrationSet: fix off by one error

Author: ENikS

src/Storage/RegistrationSet.cs

@@ -76,7 +76,7 @@ public void Add(Type type, string name, InternalRegistration registration)
             newEntry.RegisteredType = type;
             newEntry.Name = name;
             newEntry.Registration = registration;
-            newEntry.Next = _buckets[bucket] - 1;
+            newEntry.Next = _buckets[bucket];
             _buckets[bucket] = Count;
         }
 

tests/Unity.Tests/Storage/RegistrationSetTests.cs

@@ -0,0 +1,55 @@
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+using Unity.Registration;
+using Unity.Storage;
+using Unity.Tests.TestObjects;
+
+namespace Unity.Tests.v5.Storage
+{
+    [TestClass]
+    public class RegistrationSetTests
+    {
+        [TestMethod]
+        public void ShouldHandleCollisions()
+        {
+            var (s1, s2) = MakeCollision();
+
+            var registrationSet = new RegistrationSet();
+            var registration1 = new InternalRegistration();
+            var registration2 = new InternalRegistration();
+            var registration3 = new InternalRegistration();
+
+            registrationSet.Add(typeof(IService), s1, registration1);
+            Assert.AreEqual(1, registrationSet.Count);
+            registrationSet.Add(typeof(IService), s2, registration2);
+            Assert.AreEqual(2, registrationSet.Count);
+            registrationSet.Add(typeof(IService), s1, registration3);
+            Assert.AreEqual(2, registrationSet.Count);
+        }
+
+        private static (string, string) MakeCollision()
+        {
+            var strings = new Dictionary<int, string>();
+            var random = new Random();
+            var size = 10;
+
+            var builder = new StringBuilder(size);
+            while (true)
+            {
+                for (var j = 0; j < size; j++)
+                    builder.Append((char) random.Next('a', 'z' + 1));
+
+                var str = builder.ToString();
+                var hash = str.GetHashCode();
+                if (strings.TryGetValue(hash, out var other))
+                    return (str, other);
+
+                strings[hash] = str;
+                builder.Clear();
+            }
+        }
+
+    }
+}