Improvements and bug fixes to Ensure (#132)

Fixes a couple of bugs and adds NotNullOrEmpty<T>(IEnumerable<T> argument, string argumentName) to the Ensure class.

Author: joshkempner

src/ReactiveDomain.Core/Util/Ensure.cs

@@ -26,8 +26,9 @@ public static void NotNull<T>(T argument, string argumentName) where T : class
         public static void NotNullOrEmpty(string argument, string argumentName)
         {
             if (string.IsNullOrEmpty(argument))
-                throw new ArgumentNullException(argument, argumentName);
+                throw new ArgumentNullException(argumentName, argument);
         }
+
         /// <summary>
         /// Ensure that the argument (ICollection) is neither null nor empty (throw an exception if it is)
         /// </summary>
@@ -41,6 +42,19 @@ public static void NotNullOrEmpty<T>(ICollection<T> argument, string argumentNam
                 throw new ArgumentOutOfRangeException(argumentName, argumentName + " must have items.");
         }
 
+        /// <summary>
+        /// Ensure that the argument (IEnumerable) is neither null nor empty (throw an exception if it is)
+        /// </summary>
+        /// <param name="argument"></param>
+        /// <param name="argumentName"></param>
+        public static void NotNullOrEmpty<T>(IEnumerable<T> argument, string argumentName)
+        {
+            if (argument == null)
+                throw new ArgumentNullException(argumentName);
+            if (!argument.Any())
+                throw new ArgumentOutOfRangeException(argumentName, argumentName + " must have items.");
+        }
+
         /// <summary>
         /// Ensure that the argument (an int) is &gt;0 (throw an exception if it is &lt;=0)
         /// </summary>
@@ -115,7 +129,7 @@ public static void Nonnegative(decimal number, string argumentName)
         public static void NotEmptyGuid(Guid guid, string argumentName)
         {
             if (Guid.Empty == guid)
-                throw new ArgumentException(argumentName, argumentName + " shoud be non-empty GUID.");
+                throw new ArgumentException(argumentName + " should be non-empty GUID.", argumentName);
         }
 
         /// <summary>
@@ -173,7 +187,7 @@ public static void Equal(Guid expected, Guid actual, string argumentName)
         /// <param name="argumentName"></param>
         public static void PowerOf2(int argument, string argumentName)
         {
-            if ((argument <= 0) || (((uint)argument) & ((uint)argument - 1)) != 0)
+            if (argument <= 0 || ((uint)argument & ((uint)argument - 1)) != 0)
                 throw new ArgumentException($"{argumentName}: {argument} is not a power of 2");
         }