fix constructur for unit tests

Octokit.Reactive/Clients/ObservablePullRequestReviewCommentReactionsClient.cs

@@ -5,7 +5,7 @@ using System.Reactive.Threading.Tasks;
 
 namespace Octokit.Reactive
 {
-    class ObservablePullRequestReviewCommentReactionsClient : IObservablePullRequestReviewCommentReactionsClient
+    public class ObservablePullRequestReviewCommentReactionsClient : IObservablePullRequestReviewCommentReactionsClient
     {
         readonly IPullRequestReviewCommentReactionsClient _client;
         readonly IConnection _connection;

Octokit.Tests/Reactive/ObservableCommitCommentReactionClientTests.cs

@@ -7,6 +7,15 @@ namespace Octokit.Tests.Reactive
 {
     public class ObservableCommitCommentReactionClientTests
     {
+        public class TheCtor
+        {
+            [Fact]
+            public void EnsuresNonNullArguments()
+            {
+                Assert.Throws<ArgumentNullException>(() => new ObservableCommitCommentReactionsClient(null));
+            }
+        }
+
         public class TheGetAllMethod
         {
             private readonly IGitHubClient _githubClient;

Octokit.Tests/Reactive/ObservablePullRequestReviewCommentReactionsClientTests.cs

@@ -7,6 +7,16 @@ namespace Octokit.Tests.Reactive
 {
     public class ObservablePullRequestReviewCommentReactionsClientTests
     {
+
+        public class TheCtor
+        {
+            [Fact]
+            public void EnsuresNonNullArguments()
+            {
+                Assert.Throws<ArgumentNullException>(() => new ObservablePullRequestReviewCommentReactionsClient(null));
+            }
+        }
+
         public class TheGetAllMethod
         {
             private readonly IGitHubClient _githubClient;