Fixed: Trying to obtain differences from a property whose type is an specilization of Dictionary raises an exception.

Author: igece

src/ObjDiff/ObjDiff.cs

@@ -162,7 +162,23 @@ private static IEnumerable<Difference> Diff<T>(T left, T right, CompareOptions c
 
                 if (IsCollection(property))
                 {
-                    var collectionType = property.PropertyType.IsArray ? property.PropertyType.GetElementType() : property.PropertyType.GetGenericArguments()[0];
+                    Type collectionType = null;
+
+                    if (property.PropertyType.IsArray)
+                        collectionType = property.PropertyType.GetElementType();
+
+                    else
+                    {
+                        var genericArguments = property.PropertyType.GetGenericArguments();
+
+                        while (genericArguments != null && genericArguments.Length == 0)
+                            genericArguments = property.PropertyType.BaseType?.GetGenericArguments();
+
+                        if (genericArguments == null)
+                            throw new Exception("Unable to obtain generic arguments of a collection property");
+
+                        collectionType = genericArguments[0];
+                    }
 
                     if (!HasEqualityDefined(collectionType))
                         continue;
@@ -277,7 +293,9 @@ private static bool IsCollectionItem(string indexedProperty, out string property
 
         private static bool HasEqualityDefined(Type type)
         {
-            if (type.GetInterface(typeof(IEquatable<>).Name) != null)
+            var filter = new TypeFilter((c, o) => c.ToString() == o.ToString());
+
+            if (type.FindInterfaces(filter, typeof(IEquatable<>)).Length > 0)
                 return true;
 
             return type.GetMethod("Equals", new Type[] { typeof(object) }).DeclaringType != typeof(object);
@@ -312,6 +330,12 @@ bool IsNullableSimpleType(Type t)
         }
 
 
+        private static bool IsDictionary(PropertyInfo propertyInfo)
+        {
+            return propertyInfo.PropertyType.IsGenericType && propertyInfo.PropertyType.GetGenericTypeDefinition() == typeof(Dictionary<,>);
+        }
+
+
         private static bool IsCollection(PropertyInfo propertyInfo)
         {
             return propertyInfo.PropertyType != typeof(string) &&

src/ObjDiff/ObjDiff.csproj

@@ -12,8 +12,8 @@
     <Authors>Israel Gómez de Celis González</Authors>
     <Description>A C# .NET Standard library that allows to obtain the differences between two objects and, optionally, patch the first object with these differences so it becomes equal to the second one.</Description>
     <Copyright>Copyright (c) 2021 Israel Gómez de Celis González</Copyright>
-    <Version>1.3.1</Version>
-    <PackageReleaseNotes>Added support for .NET 6 DateOnly and TimeOnly structures.</PackageReleaseNotes>
+    <Version>1.3.2</Version>
+    <PackageReleaseNotes>Bug fixes.</PackageReleaseNotes>
   </PropertyGroup>
 
   <ItemGroup>