diff --git a/CSUtilities.Tests/Extensions/StringExtensionsTests.cs b/CSUtilities.Tests/Extensions/StringExtensionsTests.cs
index 0443cfc..70f7068 100644
--- a/CSUtilities.Tests/Extensions/StringExtensionsTests.cs
+++ b/CSUtilities.Tests/Extensions/StringExtensionsTests.cs
@@ -1,8 +1,4 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using CSUtilities.Extensions;
 using Xunit;
 
 namespace CSUtilities.Tests.Extensions
@@ -10,9 +6,10 @@ namespace CSUtilities.Tests.Extensions
 	public class StringExtensionsTests
 	{
 		[Fact]
-		public void GetStringValueTest()
+		public void IsNullOrEmptyTest()
 		{
-
+			string n = null;
+			Assert.True(n.IsNullOrEmpty());
 		}
 	}
 }
diff --git a/CSUtilities/Extensions/StringExtensions.cs b/CSUtilities/Extensions/StringExtensions.cs
index a887c4c..425a1b3 100644
--- a/CSUtilities/Extensions/StringExtensions.cs
+++ b/CSUtilities/Extensions/StringExtensions.cs
@@ -1,10 +1,10 @@
 using System;
 using System.Collections.Generic;
 using System.Linq;
+using System.Runtime.CompilerServices;
 
 namespace CSUtilities.Extensions
 {
-	//TODO: refactor extensions
 	/// <summary>
 	/// String utility extensions.
 	/// </summary>
@@ -25,6 +25,14 @@ public static bool IsNullOrWhiteSpace(this string str)
 			return string.IsNullOrWhiteSpace(str);
 		}
 
+		public static void TrowIfNullOrEmpty(this string str, [CallerMemberName] string name = null)
+		{
+			if (string.IsNullOrEmpty(str))
+			{
+				throw new ArgumentException("", name);
+			}
+		}
+
 		/// <summary>
 		/// Return an array with all the lines.
 		/// </summary>