From 6396e14504b8a15a641a5bf0a029e8eeb023dd63 Mon Sep 17 00:00:00 2001
From: Ryan Brandenburg <rybrande@microsoft.com>
Date: Fri, 13 Jan 2017 16:15:30 -0800
Subject: [PATCH] Add null-check back to MediaType

---
 .../Formatters/MediaType.cs                     | 17 ++++++++++-------
 .../Formatters/MediaTypeTest.cs                 | 10 ++++++++++
 2 files changed, 20 insertions(+), 7 deletions(-)

diff --git a/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs b/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs
index 7d37dcbd9b..1c7e008657 100644
--- a/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs
+++ b/src/Microsoft.AspNetCore.Mvc.Core/Formatters/MediaType.cs
@@ -55,16 +55,19 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
                 throw new ArgumentOutOfRangeException(nameof(offset));
             }
 
-            if (length < 0 || length > mediaType.Length)
+            if (length != null)
             {
-                throw new ArgumentOutOfRangeException(nameof(length));
-            }
+                if(length < 0 || length > mediaType.Length)
+                {
+                    throw new ArgumentOutOfRangeException(nameof(length));
+                }
 
-            if (offset > mediaType.Length - length)
-            {
-                throw new ArgumentException(Resources.FormatArgument_InvalidOffsetLength(nameof(offset), nameof(length)));
+                if (offset > mediaType.Length - length)
+                {
+                    throw new ArgumentException(Resources.FormatArgument_InvalidOffsetLength(nameof(offset), nameof(length)));
+                }
             }
-
+            
             _parameterParser = default(MediaTypeParameterParser);
 
             StringSegment type;
diff --git a/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs b/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs
index b5bd23dacd..95fa6c6a8d 100644
--- a/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs
+++ b/test/Microsoft.AspNetCore.Mvc.Core.Test/Formatters/MediaTypeTest.cs
@@ -60,6 +60,16 @@ namespace Microsoft.AspNetCore.Mvc.Formatters
             Assert.Equal(new StringSegment("utf-8"), result.GetParameter("charset"));
         }
 
+        [Fact]
+        public void Constructor_NullLength_IgnoresLength()
+        {
+            // Arrange & Act
+            var result = new MediaType("mediaType", 1, length: null);
+
+            // Assert
+            Assert.Equal(new StringSegment("ediaType"), result.Type);
+        }
+
         [Fact]
         public void Constructor_NullMediaType_Throws()
         {