Jiggled the comment thread hierachy a little.

Removed `Comments` from `ICommentThreadViewModel` beacuse the comments may be of different types.

Author: grokys

src/GitHub.App/SampleData/Documents/IssueishCommentThreadViewModelDesigner.cs

@@ -9,11 +9,11 @@ namespace GitHub.SampleData.Documents
 {
     public class IssueishCommentThreadViewModelDesigner : ViewModelBase, IIssueishCommentThreadViewModel
     {
-        public IReadOnlyReactiveList<ICommentViewModel> Comments { get; set; }
         public IActorViewModel CurrentUser { get; } = new ActorViewModelDesigner("grokys");
         public Task DeleteComment(int pullRequestId, int commentId) => Task.CompletedTask;
         public Task EditComment(string id, string body) => Task.CompletedTask;
         public Task InitializeAsync(ActorModel currentUser, IssueishDetailModel model, bool addPlaceholder) => Task.CompletedTask;
         public Task PostComment(string body) => Task.CompletedTask;
+        public Task CloseIssueish(string body) => Task.CompletedTask;
     }
 }

src/GitHub.App/ViewModels/CommentThreadViewModel.cs

@@ -11,8 +11,6 @@ namespace GitHub.ViewModels
     /// </summary>
     public abstract class CommentThreadViewModel : ReactiveObject, ICommentThreadViewModel
     {
-        readonly ReactiveList<ICommentViewModel> comments = new ReactiveList<ICommentViewModel>();
-
         /// <summary>
         /// Initializes a new instance of the <see cref="CommentThreadViewModel"/> class.
         /// </summary>
@@ -32,15 +30,9 @@ protected Task InitializeAsync(ActorModel currentUser)
             return Task.CompletedTask;
         }
 
-        /// <inheritdoc/>
-        public IReactiveList<ICommentViewModel> Comments => comments;
-
         /// <inheritdoc/>
         public IActorViewModel CurrentUser { get; private set; }
 
-        /// <inheritdoc/>
-        IReadOnlyReactiveList<ICommentViewModel> ICommentThreadViewModel.Comments => comments;
-
         /// <inheritdoc/>
         public abstract Task PostComment(string body);
 

src/GitHub.App/ViewModels/Documents/IIssueishCommentViewModel.cs

@@ -37,7 +37,7 @@ public interface IIssueishCommentViewModel : ICommentViewModel
         /// close the issue/pr from this comment.
         /// </param>
         Task InitializeAsync(
-            ICommentThreadViewModel thread,
+            IIssueishCommentThreadViewModel thread,
             ActorModel currentUser,
             CommentModel comment,
             string closeCaption);

src/GitHub.App/ViewModels/Documents/IssueishCommentViewModel.cs

@@ -26,6 +26,9 @@ public class IssueishCommentViewModel : CommentViewModel, IIssueishCommentViewMo
         public IssueishCommentViewModel(ICommentService commentService)
             : base(commentService)
         {
+            CloseIssueish = ReactiveCommand.CreateFromTask(
+                DoCloseIssueish,
+                this.WhenAnyValue(x => x.CanCloseIssueish));
         }
 
         /// <inheritdoc/>
@@ -39,7 +42,7 @@ public IssueishCommentViewModel(ICommentService commentService)
 
         /// <inheritdoc/>
         public async Task InitializeAsync(
-            ICommentThreadViewModel thread,
+            IIssueishCommentThreadViewModel thread,
             ActorModel currentUser,
             CommentModel comment,
             string closeCaption)
@@ -60,5 +63,10 @@ await base.InitializeAsync(
                     .ToProperty(this, x => x.CloseIssueishCaption);
             }
         }
+
+        Task DoCloseIssueish()
+        {
+            return Task.CompletedTask;
+        }
     }
 }

src/GitHub.App/ViewModels/Documents/PullRequestPageViewModel.cs

@@ -17,7 +17,7 @@ namespace GitHub.ViewModels.Documents
     /// </summary>
     [Export(typeof(IPullRequestPageViewModel))]
     [PartCreationPolicy(CreationPolicy.NonShared)]
-    public class PullRequestPageViewModel : PullRequestViewModelBase, IPullRequestPageViewModel, ICommentThreadViewModel
+    public class PullRequestPageViewModel : PullRequestViewModelBase, IPullRequestPageViewModel, IIssueishCommentThreadViewModel
     {
         readonly IViewViewModelFactory factory;
         readonly IPullRequestService service;
@@ -59,9 +59,6 @@ public PullRequestPageViewModel(
         /// <inheritdoc/>
         public ReactiveCommand<string, Unit> ShowCommit { get; }
 
-        /// <inheritdoc/>
-        IReadOnlyReactiveList<ICommentViewModel> ICommentThreadViewModel.Comments => throw new NotImplementedException();
-
         /// <inheritdoc/>
         public async Task InitializeAsync(
             IRemoteRepositoryModel repository,
@@ -129,6 +126,11 @@ Task ICommentThreadViewModel.EditComment(string id, string body)
             throw new NotImplementedException();
         }
 
+        Task IIssueishCommentThreadViewModel.CloseIssueish(string body)
+        {
+            throw new NotImplementedException();
+        }
+
         async Task AddComment(CommentModel comment)
         {
             var vm = factory.CreateViewModel<IIssueishCommentViewModel>();

src/GitHub.App/ViewModels/PullRequestReviewCommentThreadViewModel.cs

@@ -17,6 +17,7 @@ namespace GitHub.ViewModels
     [PartCreationPolicy(CreationPolicy.NonShared)]
     public class PullRequestReviewCommentThreadViewModel : CommentThreadViewModel, IPullRequestReviewCommentThreadViewModel
     {
+        readonly ReactiveList<ICommentViewModel> comments = new ReactiveList<ICommentViewModel>();
         readonly IViewViewModelFactory factory;
         readonly ObservableAsPropertyHelper<bool> needsPush;
         IPullRequestSessionFile file;
@@ -40,6 +41,9 @@ public PullRequestReviewCommentThreadViewModel(IViewViewModelFactory factory)
                 .ToProperty(this, x => x.NeedsPush);
         }
 
+        /// <inheritdoc/>
+        public IReactiveList<ICommentViewModel> Comments => comments;
+
         /// <inheritdoc/>
         public IPullRequestSession Session { get; private set; }
 
@@ -65,6 +69,9 @@ public bool IsNewThread
         /// <inheritdoc/>
         public bool NeedsPush => needsPush.Value;
 
+        /// <inheritdoc/>
+        IReadOnlyReactiveList<ICommentViewModel> IPullRequestReviewCommentThreadViewModel.Comments => comments;
+
         /// <inheritdoc/>
         public async Task InitializeAsync(
             IPullRequestSession session,

src/GitHub.Exports.Reactive/ViewModels/Documents/IIssueishCommentThreadViewModel.cs

@@ -1,6 +1,5 @@
 using System;
 using System.Threading.Tasks;
-using GitHub.Models;
 
 namespace GitHub.ViewModels.Documents
 {
@@ -10,16 +9,9 @@ namespace GitHub.ViewModels.Documents
     public interface IIssueishCommentThreadViewModel : ICommentThreadViewModel
     {
         /// <summary>
-        /// Initializes the view model with data.
+        /// Called by a comment in the thread to close the issue or pull request.
         /// </summary>
-        /// <param name="currentUser">The currently logged in user.</param>
-        /// <param name="model">The issue or pull request model.</param>
-        /// <param name="addPlaceholder">
-        /// Whether to add a placeholder comment at the end of the thread.
-        /// </param>
-        Task InitializeAsync(
-            ActorModel currentUser,
-            IssueishDetailModel model,
-            bool addPlaceholder);
+        /// <param name="body">The body of a comment to submit before closing.</param>
+        Task CloseIssueish(string body);
     }
 }

src/GitHub.Exports.Reactive/ViewModels/ICommentThreadViewModel.cs

@@ -10,12 +10,7 @@ namespace GitHub.ViewModels
     public interface ICommentThreadViewModel : IViewModel
     {
         /// <summary>
-        /// Gets the comments in the thread.
-        /// </summary>
-        IReadOnlyReactiveList<ICommentViewModel> Comments { get; }
-
-        /// <summary>
-        /// Gets the current user under whos account new comments will be created.
+        /// Gets the current user under whose account new comments will be created.
         /// </summary>
         IActorViewModel CurrentUser { get; }
 

src/GitHub.Exports.Reactive/ViewModels/IPullRequestReviewCommentThreadViewModel.cs

@@ -1,6 +1,7 @@
 using System.Threading.Tasks;
 using GitHub.Models;
 using GitHub.Services;
+using ReactiveUI;
 
 namespace GitHub.ViewModels
 {
@@ -9,6 +10,11 @@ namespace GitHub.ViewModels
     /// </summary>
     public interface IPullRequestReviewCommentThreadViewModel : ICommentThreadViewModel
     {
+        /// <summary>
+        /// Gets the comments in the thread.
+        /// </summary>
+        IReadOnlyReactiveList<ICommentViewModel> Comments { get; }
+
         /// <summary>
         /// Gets the current pull request review session.
         /// </summary>

test/GitHub.App.UnitTests/ViewModels/Documents/IssueishCommentViewModelTests.cs

@@ -1,11 +1,6 @@
-using System;
-using System.Collections.Generic;
-using System.Linq;
-using System.Text;
-using System.Threading.Tasks;
+using System.Threading.Tasks;
 using GitHub.Models;
 using GitHub.Services;
-using GitHub.ViewModels;
 using GitHub.ViewModels.Documents;
 using NSubstitute;
 using NUnit.Framework;
@@ -40,10 +35,10 @@ async Task<IssueishCommentViewModel> CreateAndInitializeTarget(
             CommentModel comment,
             string closeCaption,
             ICommentService commentService = null,
-            ICommentThreadViewModel thread = null,
+            IIssueishCommentThreadViewModel thread = null,
             ActorModel currentUser = null)
         {
-            thread = thread ?? Substitute.For<ICommentThreadViewModel>();
+            thread = thread ?? Substitute.For<IIssueishCommentThreadViewModel>();
             currentUser = currentUser ?? new ActorModel { Login = "grokys" };
 
             var target = CreateTarget(commentService);