added Empty method to T[].

jittuu · Nov 6, 2012 · f7d5e19 · f7d5e19
1 parent 2f20f04
commit f7d5e19
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diff --git a/NSupport.Test/ArrayAccessTest.cs b/NSupport.Test/ArrayAccessTest.cs
@@ -38,5 +38,21 @@ public class ArrayAccessTest {
             var ints = new[] { 1, 2, 3, 4, 5, 1 };
             Assert.Equal(-1, ints.LastIndexOf(7));
         }
+
+        [Fact]
+        public void Test_Empty_with_null() {
+            int[] ints = null;
+            Assert.Throws<ArgumentNullException>(() => ints.Empty());
+        }
+
+        [Fact]
+        public void Test_Empty_with_existing_value() {
+            var ints = new[] { 1, 2, 3, 4, 5, 1 };
+
+            var values = ints.Empty();
+
+            Assert.NotEmpty(ints);
+            Assert.Empty(values);
+        }
     }
 }
diff --git a/NSupport/ArrayAccess.cs b/NSupport/ArrayAccess.cs
@@ -30,5 +30,17 @@ public static class ArrayAccess {
 
             return Array.LastIndexOf<T>(source, value);
         }
+
+        /// <summary>
+        /// Create empty array of T without modifying <paramref name="source"/>.
+        /// </summary>
+        /// <typeparam name="T">The type of the elements of <paramref name="source"/>.</typeparam>
+        /// <param name="source">An instance of <see cref="Array"/>.</param>
+        /// <returns>Empty array of T.</returns>
+        public static T[] Empty<T>(this T[] source) {
+            Guard.ArgumentNotNull("source", source);
+            source = new T[] { };            
+            return source;
+        }
     }
 }