Add GetDisplayName to enum extensions

UnitTests/Common/Extensions/EnumExtensionsTests.cs

@@ -1,7 +1,8 @@
 using System;
+using System.ComponentModel.DataAnnotations;
 using System.Linq;
-using UnitTests.Common.Utils;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
+using UnitTests.Common.Utils;
 using DescriptionAttribute = System.ComponentModel.DescriptionAttribute;
 
 namespace UnitTests.Common.Extensions
@@ -107,6 +108,22 @@ namespace UnitTests.Common.Extensions
 			Assert.IsFalse(list.Any());
 		}
 
+		[TestMethod]
+		public void ShouldReturnDisplayNameOrStringRepresentation()
+		{
+			// arrange
+			var enumWithDisplayName = TestEnum.Two;
+			var enumWithoutDisplayName = TestEnum.Zero;
+
+			// act
+			string displayName = enumWithDisplayName.GetDisplayName();
+			string noDisplayName = enumWithoutDisplayName.GetDisplayName();
+
+			// assert
+			Assert.AreEqual("Zwei", displayName);
+			Assert.AreEqual(enumWithoutDisplayName.ToString(), noDisplayName);
+		}
+
 		internal enum TestEnum
 		{
 			[CustomMultiple("nix")]
@@ -115,6 +132,7 @@ namespace UnitTests.Common.Extensions
 			Zero,
 			[Description("Eins")]
 			One,
+			[Display(Name = "Zwei")]
 			Two,
 		}
 	}