added some tests around uploading assets

Octokit.Tests.Integration/Helper.cs

@@ -1,6 +1,8 @@
 using System;
 using System.Diagnostics;
+using System.IO;
 using System.Net.Http.Headers;
+using System.Reflection;
 
 namespace Octokit.Tests.Integration
 {
@@ -57,5 +59,17 @@ namespace Octokit.Tests.Integration
         {
             return string.Concat(name, "-", DateTime.UtcNow.ToString("yyyyMMddhhmmssfff"));
         }
+
+        public static Stream LoadFixture(string fileName)
+        {
+            var key = "Octokit.Tests.Integration.fixtures." + fileName;
+            var stream = typeof(Helper).Assembly.GetManifestResourceStream(key);
+            if (stream == null)
+            {
+                throw new InvalidOperationException(
+                    "The file '" + fileName + "' was not found as an embedded resource in the assembly. Failing the test...");
+            }
+            return stream;
+        }
     }
 }