fix Insert<T> when T is declared as IEnumerable<T> (#948)

Dapper.Contrib/SqlMapperExtensions.Async.cs

@@ -148,11 +148,19 @@ public static partial class SqlMapperExtensions
                 isList = true;
                 type = type.GetElementType();
             }
-            else if (type.IsGenericType() && type.GetTypeInfo().ImplementedInterfaces.Any(ti => ti.IsGenericType() && ti.GetGenericTypeDefinition() == typeof(IEnumerable<>)))
+            else if (type.IsGenericType())
+            {
+                var typeInfo = type.GetTypeInfo();
+                bool implementsGenericIEnumerableOrIsGenericIEnumerable =
+                    typeInfo.ImplementedInterfaces.Any(ti => ti.IsGenericType() && ti.GetGenericTypeDefinition() == typeof(IEnumerable<>)) ||
+                    typeInfo.GetGenericTypeDefinition() == typeof(IEnumerable<>);
+
+                if (implementsGenericIEnumerableOrIsGenericIEnumerable)
                 {
                     isList = true;
                     type = type.GetGenericArguments()[0];
                 }
+            }
 
             var name = GetTableName(type);
             var sbColumnList = new StringBuilder(null);

Dapper.Contrib/SqlMapperExtensions.cs

@@ -332,11 +332,19 @@ private static string GetTableName(Type type)
                 isList = true;
                 type = type.GetElementType();
             }
-            else if (type.IsGenericType() && type.GetTypeInfo().ImplementedInterfaces.Any(ti => ti.IsGenericType() && ti.GetGenericTypeDefinition() == typeof(IEnumerable<>)))
+            else if (type.IsGenericType())
+            {
+                var typeInfo = type.GetTypeInfo();
+                bool implementsGenericIEnumerableOrIsGenericIEnumerable =
+                    typeInfo.ImplementedInterfaces.Any(ti => ti.IsGenericType() && ti.GetGenericTypeDefinition() == typeof(IEnumerable<>)) ||
+                    typeInfo.GetGenericTypeDefinition() == typeof(IEnumerable<>);
+
+                if (implementsGenericIEnumerableOrIsGenericIEnumerable)
                 {
                     isList = true;
                     type = type.GetGenericArguments()[0];
                 }
+            }
 
             var name = GetTableName(type);
             var sbColumnList = new StringBuilder(null);

Dapper.Tests.Contrib/TestSuite.Async.cs

@@ -225,6 +225,12 @@ public async Task BuilderTemplateWithoutCompositionAsync()
             }
         }
 
+        [Fact]
+        public async Task InsertEnumerableAsync()
+        {
+            await InsertHelperAsync(src => src.AsEnumerable()).ConfigureAwait(false);
+        }
+
         [Fact]
         public async Task InsertArrayAsync()
         {

Dapper.Tests.Contrib/TestSuite.cs

@@ -324,6 +324,12 @@ public void TestClosedConnection()
             }
         }
 
+        [Fact]
+        public void InsertEnumerable()
+        {
+            InsertHelper(src => src.AsEnumerable());
+        }
+
         [Fact]
         public void InsertArray()
         {