Add additonal log to TestUnreadMessagesCount

Author: jakub-grzesiowski

c-sharp-chat/PubnubChatApi/PubNubChatApi.Tests/MembershipTests.cs

@@ -152,6 +152,7 @@ public async Task TestUnreadMessagesCount()
 
         var membership = (await unreadChannel.GetMemberships())
             .Memberships.FirstOrDefault(x => x.UserId == user.Id);
-        Assert.True(membership != null && await membership.GetUnreadMessagesCount() >= 3);
+        var unreadCount = membership == null ? -1 : await membership.GetUnreadMessagesCount();
+        Assert.True(unreadCount >= 3, $"Expected >=3 unread but got: {unreadCount}");
     }
 }