Fix equality comparisons

Author: shana

src/GitHub.App/Models/PullRequestModel.cs

@@ -9,7 +9,9 @@
 namespace GitHub.Models
 {
     [DebuggerDisplay("{DebuggerDisplay,nq}")]
-    public sealed class PullRequestModel : NotificationAwareObject, IPullRequestModel
+    public sealed class PullRequestModel : NotificationAwareObject, IPullRequestModel,
+        IEquatable<PullRequestModel>,
+        IComparable<PullRequestModel>
     {
         public PullRequestModel(int number, string title,
             IAccount author, [AllowNull]IAccount assignee,
@@ -45,7 +47,7 @@ public override bool Equals([AllowNull]object obj)
 
         public override int GetHashCode()
         {
-            return Number;
+            return Number.GetHashCode();
         }
 
         bool IEquatable<IPullRequestModel>.Equals([AllowNull]IPullRequestModel other)
@@ -55,11 +57,23 @@ bool IEquatable<IPullRequestModel>.Equals([AllowNull]IPullRequestModel other)
             return other != null && Number == other.Number;
         }
 
+        bool IEquatable<PullRequestModel>.Equals([AllowNull]PullRequestModel other)
+        {
+            if (ReferenceEquals(this, other))
+                return true;
+            return other != null && Number == other.Number;
+        }
+
         public int CompareTo([AllowNull]IPullRequestModel other)
         {
             return other != null ? UpdatedAt.CompareTo(other.UpdatedAt) : 1;
         }
 
+        public int CompareTo([AllowNull]PullRequestModel other)
+        {
+            return other != null ? UpdatedAt.CompareTo(other.UpdatedAt) : 1;
+        }
+
         public static bool operator >([AllowNull]PullRequestModel lhs, [AllowNull]PullRequestModel rhs)
         {
             if (ReferenceEquals(lhs, rhs))
@@ -76,7 +90,7 @@ public int CompareTo([AllowNull]IPullRequestModel other)
 
         public static bool operator ==([AllowNull]PullRequestModel lhs, [AllowNull]PullRequestModel rhs)
         {
-            return Equals(lhs, rhs) && ((object)lhs == null || lhs.CompareTo(rhs) == 0);
+            return ReferenceEquals(lhs, rhs);
         }
 
         public static bool operator !=([AllowNull]PullRequestModel lhs, [AllowNull]PullRequestModel rhs)

src/UnitTests/GitHub.App/Models/PullRequestModelTests.cs

@@ -80,8 +80,8 @@ public void ComparisonEquals()
     {
         PullRequestModel left = new PullRequestModel(1, "", Substitute.For<IAccount>(), Substitute.For<IAccount>(), Now, Now + TimeSpan.FromMilliseconds(1));
         PullRequestModel right = new PullRequestModel(1, "", Substitute.For<IAccount>(), Substitute.For<IAccount>(), Now, Now + TimeSpan.FromMilliseconds(1));
-        Assert.True(left == right);
-        Assert.False(left != right);
+        Assert.False(left == right);
+        Assert.True(left != right);
         Assert.False(left > right);
         Assert.False(left < right);
     }