Fixes Issue #185.

src/AutoMapper.Extensions.ExpressionMapping/MapperExtensions.cs

@@ -260,17 +260,29 @@ public static Dictionary<Type, Type> AddTypeMapping<TSource, TDest>(this Diction
 
         private static bool HasUnderlyingType(this Type type)
         {
-            return (type.IsGenericType() && typeof(System.Collections.IEnumerable).IsAssignableFrom(type)) || type.IsArray;
+            return (type.IsGenericType() && type.GetGenericArguments().Length > 0) || type.IsArray;
         }
 
         private static void AddUnderlyingTypes(this Dictionary<Type, Type> typeMappings, IConfigurationProvider configurationProvider, Type sourceType, Type destType)
         {
-            typeMappings.DoAddTypeMappings
-            (
-                configurationProvider,
-                !sourceType.HasUnderlyingType() ? new List<Type>() : ElementTypeHelper.GetElementTypes(sourceType).ToList(),
-                !destType.HasUnderlyingType() ? new List<Type>() : ElementTypeHelper.GetElementTypes(destType).ToList()
-            );
+            if ((sourceType.IsGenericType() && typeof(System.Collections.IEnumerable).IsAssignableFrom(sourceType)) || sourceType.IsArray)
+            {
+                typeMappings.DoAddTypeMappings
+                (
+                    configurationProvider,
+                    !sourceType.HasUnderlyingType() ? new List<Type>() : ElementTypeHelper.GetElementTypes(sourceType).ToList(),
+                    !destType.HasUnderlyingType() ? new List<Type>() : ElementTypeHelper.GetElementTypes(destType).ToList()
+                );
+            }
+            else if (sourceType.IsGenericType() && destType.IsGenericType())
+            {
+                typeMappings.DoAddTypeMappings
+                (
+                    configurationProvider,
+                    !sourceType.HasUnderlyingType() ? new List<Type>() : sourceType.GetGenericArguments().ToList(),
+                    !destType.HasUnderlyingType() ? new List<Type>() : destType.GetGenericArguments().ToList()
+                );
+            }
         }
 
         /// <summary>

tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/SetPropertyCalls.cs

@@ -0,0 +1,18 @@
+using System;
+
+namespace AutoMapper.Extensions.ExpressionMapping.UnitTests
+{
+    public class SetPropertyCalls<TSource>
+    {
+        public SetPropertyCalls<TSource> SetProperty<TProperty>(
+        Func<TSource, TProperty> propertyExpression,
+        Func<TSource, TProperty> valueExpression)
+        => throw new InvalidOperationException();
+
+
+        public SetPropertyCalls<TSource> SetProperty<TProperty>(
+            Func<TSource, TProperty> propertyExpression,
+            TProperty valueExpression)
+            => throw new InvalidOperationException();
+    }
+}

tests/AutoMapper.Extensions.ExpressionMapping.UnitTests/XpressionMapperTests.cs

@@ -884,6 +884,19 @@ public void Map_accountModel_to_account_with_null_checks_against_string_type()
             Assert.True(accounts.Count == 0);
         }
 
+        [Fact]
+        public void Map_SetPropertyCalls()
+        {
+            //Arrange
+            Expression<Func<SetPropertyCalls<AccountModel>, SetPropertyCalls<AccountModel>>> exp = s => s.SetProperty(p => p.Description, "newName");
+
+            //Act
+            Expression<Func<SetPropertyCalls<Account>, SetPropertyCalls<Account>>> expMapped = mapper.MapExpression<Expression<Func<SetPropertyCalls<Account>, SetPropertyCalls<Account>>>>(exp);
+
+            //Assert
+            Assert.NotNull(expMapped);
+        }
+
         [Fact]
         public void Map_accountModel_to_account_with_left_null_checks_against_string_type()
         {