[WIP] Gists get Commits and Forks

- [ ] Finish Gists API Implementation
- [ ] [Add method to get gist
commits](https://developer.github.com/v3/gists/#list-gist-commits)
- [ ] [Add method to get gist
forks](https://developer.github.com/v3/gists/#list-gist-forks)

Fixes #328, Fixes #216

Added implementation for the remaining pieces of the Gists API.  The
others mentioned in #328 and #216 were completed through other PRs.

Octokit.Reactive/Clients/IObservableGistsClient.cs

@@ -91,6 +91,24 @@ namespace Octokit.Reactive
         /// <param name="since">Only gists updated at or after this time are returned</param>
         IObservable<Gist> GetAllForUser(string user, DateTimeOffset since);
 
+        /// <summary>
+        /// List gist commits
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-commits
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        IObservable<GistHistory> GetCommits(string id);
+
+        /// <summary>
+        /// List gist forks
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-forks
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        IObservable<GistFork> GetForks(string id);
+
         /// <summary>
         /// Creates a new gist
         /// </summary>

Octokit.Reactive/Clients/ObservableGistsClient.cs

@@ -180,6 +180,34 @@ namespace Octokit.Reactive
             return _connection.GetAndFlattenAllPages<Gist>(ApiUrls.UsersGists(user), request.ToParametersDictionary());
         }
 
+        /// <summary>
+        /// List gist commits
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-commits
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        public IObservable<GistHistory> GetCommits(string id)
+        {
+            Ensure.ArgumentNotNullOrEmptyString(id, "id");
+
+            return _connection.GetAndFlattenAllPages<GistHistory>(ApiUrls.GistCommits(id));
+        }
+
+        /// <summary>
+        /// List gist forks
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-forks
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        public IObservable<GistFork> GetForks(string id)
+        {
+            Ensure.ArgumentNotNullOrEmptyString(id, "id");
+
+            return _connection.GetAndFlattenAllPages<GistFork>(ApiUrls.ForkGist(id));
+        }
+
         /// <summary>
         /// Edits a gist
         /// </summary>

Octokit.Tests.Integration/Clients/GistsClientTests.cs

@@ -126,4 +126,16 @@ public class GistsClientTests
 
         await _fixture.Delete(createdGist.Id);
     }
+
+    [IntegrationTest]
+    public async Task CanGetGistChildren()
+    {
+        // Test History/Commits
+        var commits = await _fixture.GetCommits(testGistId);
+        Assert.NotNull(commits);
+
+        // Test Forks
+        var forks = await _fixture.GetForks(testGistId);
+        Assert.NotNull(forks);
+    }
 }

Octokit.Tests/Clients/GistsClientTests.cs

@@ -124,6 +124,44 @@ public class GistsClientTests
         }
     }
 
+    public class TheGetChildrenMethods
+    {
+        [Fact]
+        public void EnsureNonNullArguments()
+        {
+            var connection = Substitute.For<IApiConnection>();
+            var client = new GistsClient(connection);
+
+            Assert.Throws<ArgumentNullException>(() => client.GetCommits(null));
+            Assert.Throws<ArgumentException>(() => client.GetCommits(""));
+
+            Assert.Throws<ArgumentNullException>(() => client.GetForks(null));
+            Assert.Throws<ArgumentException>(() => client.GetForks(""));
+        }
+
+        [Fact]
+        public void RequestsCorrectGetCommitsUrl()
+        {
+            var connection = Substitute.For<IApiConnection>();
+            var client = new GistsClient(connection);
+
+            client.GetCommits("9257657");
+
+            connection.Received().GetAll<GistHistory>(Arg.Is<Uri>(u => u.ToString() == "gists/9257657/commits"));
+        }
+
+        [Fact]
+        public void RequestsCorrectGetForksUrl()
+        {
+            var connection = Substitute.For<IApiConnection>();
+            var client = new GistsClient(connection);
+
+            client.GetForks("9257657");
+
+            connection.Received().GetAll<GistFork>(Arg.Is<Uri>(u => u.ToString() == "gists/9257657/forks"));
+        }
+    }
+
     public class TheCreateMethod
     {
         [Fact]

Octokit.Tests/Octokit.Tests.csproj

@@ -162,6 +162,7 @@
     <Compile Include="Reactive\ObservablePullRequestReviewCommentsClientTests.cs" />
     <Compile Include="Reactive\ObservableRepositoriesClientTests.cs" />
     <Compile Include="Reactive\ObservableRepositoryDeployKeysClientTests.cs" />
+    <Compile Include="Reactive\ObservableGistsTests.cs" />
     <Compile Include="Reactive\ObservableStarredClientTests.cs" />
     <Compile Include="Reactive\ObservableStatisticsClientTests.cs" />
     <Compile Include="Reactive\ObservableTreesClientTests.cs" />

Octokit.Tests/Reactive/ObservableGistsTests.cs

@@ -0,0 +1,57 @@
+using System;
+using System.Collections.Generic;
+using System.Reactive.Linq;
+using System.Threading.Tasks;
+using NSubstitute;
+using Octokit;
+using Octokit.Internal;
+using Octokit.Reactive;
+using Octokit.Reactive.Internal;
+using Octokit.Tests.Helpers;
+using Xunit;
+using Xunit.Extensions;
+
+namespace Octokit.Tests.Reactive
+{
+    public class ObservableGistsTests
+    {
+        public class TheGetChildrenMethods
+        {
+            [Fact]
+            public async Task EnsureNonNullArguments()
+            {
+                var client = new ObservableGistsClient(Substitute.For<IGitHubClient>());
+
+                await AssertEx.Throws<ArgumentNullException>(async () => await client.GetCommits(null));
+                await AssertEx.Throws<ArgumentException>(async () => await client.GetCommits(""));
+
+                await AssertEx.Throws<ArgumentNullException>(async () => await client.GetForks(null));
+                await AssertEx.Throws<ArgumentException>(async () => await client.GetForks(""));
+            }
+
+            [Fact]
+            public void RequestsCorrectGetCommitsUrl()
+            {
+                var github = Substitute.For<IGitHubClient>();
+                var client = new ObservableGistsClient(github);
+                var expected = new Uri("gists/9257657/commits", UriKind.Relative);
+
+                client.GetCommits("9257657");
+
+                github.Connection.Received(1).Get<List<GistHistory>>(expected, Arg.Any<IDictionary<string, string>>(), null);
+            }
+
+            [Fact]
+            public void RequestsCorrectGetForksUrl()
+            {
+                var github = Substitute.For<IGitHubClient>();
+                var client = new ObservableGistsClient(github);
+                var expected = new Uri("gists/9257657/forks", UriKind.Relative);
+
+                client.GetForks("9257657");
+
+                github.Connection.Received(1).Get<List<GistFork>>(expected, Arg.Any<IDictionary<string, string>>(), null);
+            }
+        }
+    }
+}

Octokit/Clients/GistsClient.cs

@@ -196,6 +196,34 @@ namespace Octokit
             return ApiConnection.GetAll<Gist>(ApiUrls.UsersGists(user), request.ToParametersDictionary());
         }
 
+        /// <summary>
+        /// List gist commits
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-commits
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        public Task<IReadOnlyList<GistHistory>> GetCommits(string id)
+        {
+            Ensure.ArgumentNotNullOrEmptyString(id, "id");
+
+            return ApiConnection.GetAll<GistHistory>(ApiUrls.GistCommits(id));
+        }
+
+        /// <summary>
+        /// List gist forks
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-forks
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        public Task<IReadOnlyList<GistFork>> GetForks(string id)
+        {
+            Ensure.ArgumentNotNullOrEmptyString(id, "id");
+
+            return ApiConnection.GetAll<GistFork>(ApiUrls.ForkGist(id));
+        }
+
         /// <summary>
         /// Edits a gist
         /// </summary>

Octokit/Clients/IGistsClient.cs

@@ -98,6 +98,24 @@ namespace Octokit
         /// <param name="since">Only gists updated at or after this time are returned</param>
         Task<IReadOnlyList<Gist>> GetAllForUser(string user, DateTimeOffset since);
 
+        /// <summary>
+        /// List gist commits
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-commits
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        Task<IReadOnlyList<GistHistory>> GetCommits(string id);
+
+        /// <summary>
+        /// List gist forks
+        /// </summary>
+        /// <remarks>
+        /// http://developer.github.com/v3/gists/#list-gists-forks
+        /// </remarks>
+        /// <param name="id">The id of the gist</param>
+        Task<IReadOnlyList<GistFork>> GetForks(string id);
+
         /// <summary>
         /// Creates a new gist
         /// </summary>

Octokit/Helpers/ApiUrls.cs

@@ -646,6 +646,10 @@ namespace Octokit
             return "gists/{0}".FormatUri(id);
         }
 
+        /// <summary>
+        /// Returns the <see cref="Uri"/> for the forks for the specified gist.
+        /// </summary>
+        /// <param name="id">The id of the gist</param>
         public static Uri ForkGist(string id)
         {
             return "gists/{0}/forks".FormatUri(id);
@@ -680,6 +684,15 @@ namespace Octokit
             return "gists/{0}/comments".FormatUri(gistId);
         }
 
+        /// <summary>
+        /// Returns the <see cref="Uri"/> for the commits for the specified gist.
+        /// </summary>
+        /// <param name="id">The id of the gist</param>
+        public static Uri GistCommits(string id)
+        {
+            return "gists/{0}/commits".FormatUri(id);
+        }
+
         /// <summary>
         /// Returns the <see cref="Uri"/> that returns the specified pull request.
         /// </summary>