Added NewArbitraryMarkdown class, RenderArbitraryMakrdown method and unit tests for it.

Octokit.Reactive/Clients/IObservableMiscellaneousClient.cs

@@ -14,6 +14,14 @@ namespace Octokit.Reactive
             Justification = "Makes a network request")]
         IObservable<Emoji> GetAllEmojis();
 
+        /// <summary>
+        /// Gets the rendered Markdown for an arbitrary markdown document.
+        /// </summary>
+        /// <param name="markdown">An arbitrary Markdown document</param>
+        /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
+        /// <returns>The rendered Markdown.</returns>
+        IObservable<string> RenderArbitraryMarkdown(NewArbitraryMarkdown markdown);
+
         /// <summary>
         /// Gets the rendered Markdown for the specified plain-text Markdown document.
         /// </summary>

Octokit.Reactive/Clients/ObservableMiscellaneousClient.cs

@@ -26,6 +26,17 @@ namespace Octokit.Reactive
             return _client.GetAllEmojis().ToObservable().SelectMany(e => e);
         }
 
+        /// <summary>
+        /// Gets the rendered Markdown for an arbitrary markdown document.
+        /// </summary>
+        /// <param name="markdown">An arbitrary Markdown document</param>
+        /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
+        /// <returns>The rendered Markdown.</returns>
+        public IObservable<string> RenderArbitraryMarkdown(NewArbitraryMarkdown markdown)
+        {
+            return _client.RenderArbitraryMarkdown(markdown).ToObservable();
+        }
+
         /// <summary>
         /// Gets the rendered Markdown for the specified plain-text Markdown document.
         /// </summary>

Octokit.Tests/Clients/MiscellaneousClientTests.cs

@@ -31,7 +31,27 @@ namespace Octokit.Tests.Clients
                     "text/plain");
             }
         }
+        public class TheRenderArbitrryMarkdownMethod
+        {
+            [Fact]
+            public async Task RequestsTheEmojiEndpoint()
+            {
+                IApiResponse<string> response = new ApiResponse<string>(new Response(), "<strong>Test</strong>");
+                var connection = Substitute.For<IConnection>();
+                var forTest = new NewArbitraryMarkdown("testMarkdown", "gfm", "testContext");
+                connection.Post<string>(Args.Uri,forTest, "text/html", "text/plain")
+                    .Returns(Task.FromResult(response));
+                var client = new MiscellaneousClient(connection);
 
+                var html = await client.RenderArbitraryMarkdown(forTest);
+                Assert.Equal("<strong>Test</strong>", html);
+                connection.Received()
+                    .Post<string>(Arg.Is<Uri>(u => u.ToString() == "markdown"),
+                    forTest,
+                    "text/html",
+                    "text/plain");
+            }
+        }
         public class TheGetEmojisMethod
         {
             [Fact]

Octokit/Clients/IMiscellaneousClient.cs

@@ -30,6 +30,14 @@ namespace Octokit
         /// <returns>The rendered Markdown.</returns>
         Task<string> RenderRawMarkdown(string markdown);
 
+        /// <summary>
+        /// Gets the rendered Markdown for an arbitrary markdown document.
+        /// </summary>
+        /// <param name="markdown">An arbitrary Markdown document</param>
+        /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
+        /// <returns>The rendered Markdown.</returns>
+        Task<string> RenderArbitraryMarkdown(NewArbitraryMarkdown markdown);
+
         /// <summary>
         /// List all templates available to pass as an option when creating a repository.
         /// </summary>

Octokit/Clients/MiscellaneousClient.cs

@@ -58,6 +58,20 @@ namespace Octokit
             return response.Body;
         }
 
+        /// <summary>
+        /// Gets the rendered Markdown for an arbitrary markdown document.
+        /// </summary>
+        /// <param name="markdown">An arbitrary Markdown document</param>
+        /// <exception cref="ApiException">Thrown when a general API error occurs.</exception>
+        /// <returns>The rendered Markdown.</returns>
+        public async Task<string> RenderArbitraryMarkdown(NewArbitraryMarkdown markdown)
+        {
+            var endpoint = new Uri("markdown", UriKind.Relative);
+            var response = await _connection.Post<string>(endpoint, markdown, "text/html", "text/plain")
+                .ConfigureAwait(false);
+            return response.Body;
+        }
+
         /// <summary>
         /// List all templates available to pass as an option when creating a repository.
         /// </summary>

Octokit/Models/Request/NewArbitraryMarkDown.cs

@@ -0,0 +1,100 @@
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.Globalization;
+using System.Linq;
+
+namespace Octokit
+{
+    /// <summary>
+    /// Used to create anarbitrary markdown
+    /// </summary>
+    /// <remarks>
+    /// API: https://developer.github.com/v3/markdown/#render-an-arbitrary-markdown-document
+    /// </remarks>
+    [DebuggerDisplay("{DebuggerDisplay,nq}")]
+    public class NewArbitraryMarkdown
+    {
+        const string _markdown = "markdown";
+        const string _gfm = "gfm";
+
+        /// <summary>
+        /// Create an arbitrary markdown
+        /// </summary>
+        /// <param name="text">The Markdown text to render</param>
+        /// <param name="mode">The rendering mode. Can be either markdown by default or gfm</param>
+        /// <param name="context">
+        /// The repository context. Only taken into account when rendering as gfm
+        /// </param>
+        public NewArbitraryMarkdown(string text, string mode, string context)
+        {
+            Text = text;
+            Mode = GetMode(mode);
+            Context = context;
+        }
+
+        /// <summary>
+        /// Create an arbitrary markdown
+        /// </summary>
+        /// <param name="text">The Markdown text to render
+        /// </param>
+        
+        public NewArbitraryMarkdown(string text)
+            :this(text,_markdown,null)
+        {
+        }
+
+        /// <summary>
+        /// Create an arbitrary markdown
+        /// </summary>
+        /// <param name="text">The Markdown text to render</param>
+        /// <param name="mode">The rendering mode. Can be either markdown by default or gfm</param>
+        /// </param>
+        public NewArbitraryMarkdown(string text, string mode)
+            : this(text, mode, null)
+        { 
+        }
+
+        /// <summary>
+        /// Gets the markdown text
+        /// </summary>
+        /// <value>
+        /// The text.
+        /// </value>
+        public string Text { get; private set; }
+
+        /// <summary>
+        /// Gets the mode of the text
+        /// </summary>
+        /// <value>
+        /// The mode.
+        /// </value>
+        public string Mode { get; private set; }
+
+        /// <summary>
+        /// Gets the context of the markdown
+        /// </summary>
+        /// <value>
+        /// The context.
+        /// </value>
+        public string Context { get; private set; }
+
+        [System.Diagnostics.CodeAnalysis.SuppressMessage("Microsoft.Naming", "CA2204:Literals should be spelled correctly", MessageId = "gfm")]
+        static string GetMode(string mode)        
+        {
+            if (mode != _markdown || mode != _gfm)
+            {
+                throw (new FormatException("The mode must be either 'markdown' or 'gfm'"));
+            }
+            else
+                return mode;
+        }
+        internal string DebuggerDisplay
+        {
+            get
+            {
+                return String.Format(CultureInfo.InvariantCulture, "Text: {0}", Text);
+            }
+        }
+    }
+}

Octokit/Octokit-Mono.csproj

@@ -104,6 +104,7 @@
     <Compile Include="Models\Request\LabelUpdate.cs" />
     <Compile Include="Models\Request\MergePullRequest.cs" />
     <Compile Include="Models\Request\MilestoneUpdate.cs" />
+    <Compile Include="Models\Request\NewArbitraryMarkDown.cs" />
     <Compile Include="Models\Request\NewBlob.cs" />
     <Compile Include="Models\Request\NewCommit.cs" />
     <Compile Include="Models\Request\NewCommitStatus.cs" />
@@ -405,4 +406,4 @@
     <Compile Include="Models\Common\Committer.cs" />
   </ItemGroup>
   <Import Project="$(MSBuildBinPath)\Microsoft.CSharp.targets" />
-</Project>
+</Project>

Octokit/Octokit-Portable.csproj

@@ -184,6 +184,7 @@
     <Compile Include="Models\Request\MergePullRequest.cs" />
     <Compile Include="Models\Request\MilestoneRequest.cs" />
     <Compile Include="Models\Request\MilestoneUpdate.cs" />
+    <Compile Include="Models\Request\NewArbitraryMarkDown.cs" />
     <Compile Include="Models\Request\NewAuthorization.cs" />
     <Compile Include="Models\Request\NewBlob.cs" />
     <Compile Include="Models\Request\NewCommit.cs" />
@@ -430,4 +431,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>

Octokit/Octokit.csproj

@@ -87,6 +87,7 @@
     <Compile Include="Http\ProductHeaderValue.cs" />
     <Compile Include="Http\RequestBody.cs" />
     <Compile Include="Models\Request\GistFileUpdate.cs" />
+    <Compile Include="Models\Request\NewArbitraryMarkDown.cs" />
     <Compile Include="Models\Request\NewMerge.cs" />
     <Compile Include="Models\Request\PublicRepositoryRequest.cs" />
     <Compile Include="Models\Request\ReleaseAssetUpload.cs" />
@@ -441,4 +442,4 @@
   <Target Name="AfterBuild">
   </Target>
   -->
-</Project>
+</Project>