Performance improvements in AssertEqualityComparer (conditional IEqua…

…table<Y> and IComparable<Y> with type caching)

Sdk/AssertEqualityComparer.cs

@@ -13,6 +13,7 @@
 
 using System;
 using System.Collections;
+using System.Collections.Concurrent;
 using System.Collections.Generic;
 using System.Reflection;
 
@@ -31,6 +32,8 @@ sealed class AssertEqualityComparer<T> : IEqualityComparer<T>
 	{
 		internal static readonly IEqualityComparer DefaultInnerComparer = new AssertEqualityComparerAdapter<object>(new AssertEqualityComparer<object>());
 
+		static readonly ConcurrentDictionary<Type, TypeInfo> cacheOfIComparableOfT = new ConcurrentDictionary<Type, TypeInfo>();
+		static readonly ConcurrentDictionary<Type, TypeInfo> cacheOfIEquatableOfT = new ConcurrentDictionary<Type, TypeInfo>();
 		readonly Lazy<IEqualityComparer> innerComparer;
 		static readonly Type typeKeyValuePair = typeof(KeyValuePair<,>);
 
@@ -86,12 +89,14 @@ public AssertEqualityComparer(IEqualityComparer innerComparer = null)
 			if (equatable != null)
 				return equatable.Equals(y);
 
-			// Implements IEquatable<typeof(y)>?
 			var xType = x.GetType();
 			var xTypeInfo = xType.GetTypeInfo();
 			var yType = y.GetType();
 
-			var iequatableY = typeof(IEquatable<>).MakeGenericType(yType).GetTypeInfo();
+			// Implements IEquatable<typeof(y)>?
+			if (xType != yType)
+			{
+				var iequatableY = cacheOfIEquatableOfT.GetOrAdd(yType, (t) => typeof(IEquatable<>).MakeGenericType(t).GetTypeInfo());
 				if (iequatableY.IsAssignableFrom(xTypeInfo))
 				{
 					var equalsMethod = iequatableY.GetDeclaredMethod(nameof(IEquatable<T>.Equals));
@@ -104,6 +109,7 @@ public AssertEqualityComparer(IEqualityComparer innerComparer = null)
 				return (bool)equalsMethod.Invoke(x, new object[] { y });
 #endif
 				}
+			}
 
 			// Implements IStructuralEquatable?
 			var structuralEquatable = x as IStructuralEquatable;
@@ -127,7 +133,9 @@ public AssertEqualityComparer(IEqualityComparer innerComparer = null)
 			}
 
 			// Implements IComparable<typeof(y)>?
-			var icomparableY = typeof(IComparable<>).MakeGenericType(yType).GetTypeInfo();
+			if (xType != yType)
+			{
+				var icomparableY = cacheOfIComparableOfT.GetOrAdd(yType, (t) => typeof(IComparable<>).MakeGenericType(t).GetTypeInfo());
 				if (icomparableY.IsAssignableFrom(xTypeInfo))
 				{
 					var compareToMethod = icomparableY.GetDeclaredMethod(nameof(IComparable<T>.CompareTo));
@@ -149,6 +157,7 @@ public AssertEqualityComparer(IEqualityComparer innerComparer = null)
 						// If this happens, just swallow up the exception and continue comparing.
 					}
 				}
+			}
 
 			// Implements IComparable?
 			var comparable = x as IComparable;