{"id":63,"date":"2015-01-16T15:00:00","date_gmt":"2015-01-16T03:00:00","guid":{"rendered":"https:\/\/blogs.msdn.microsoft.com\/visualstudioalm\/2015\/01\/16\/walkthrough-of-live-debugging-using-intellitrace-in-visual-studio-2015-text-editor\/"},"modified":"2022-05-25T01:18:24","modified_gmt":"2022-05-25T09:18:24","slug":"walkthrough-of-live-debugging-using-intellitrace-in-visual-studio-2015-text-editor","status":"publish","type":"post","link":"https:\/\/devblogs.microsoft.com\/devops\/walkthrough-of-live-debugging-using-intellitrace-in-visual-studio-2015-text-editor\/","title":{"rendered":"Walkthrough of Live Debugging using IntelliTrace in Visual Studio 2015 (Text Editor)"},"content":{"rendered":"

In this blog post I am going to walk you through fixing a bug using IntelliTrace in Visual Studio 2015. If you haven\u2019t done so already, check out the announcement of IntelliTrace in Visual Studio 2015<\/a> which gives you an overview of IntelliTrace and its UI. You can see this walkthrough as a video here<\/a> (demo start at 4m5s).<\/p>\n

The application I am going to be working with is a simple text editor built using WPF (I have included the source code<\/a> in case you want to follow along):<\/p>\n

\"clip_image001\"<\/p>\n

The bug I want to fix has to do with saving the file after it has been edited, so let\u2019s open a file first:<\/p>\n

\"clip_image002\"<\/p>\n

The contents of the file are not important. The bug I want to fix is that if I make any changes and I click on the \u201cSave\u201d button, the scrollbar will move to the top and so will my cursor:<\/p>\n

\"clip_image003\"<\/p>\n

\"clip_image004\"<\/p>\n

Let\u2019s start by trying to fix this bug using just the debugger with IntelliTrace turned off. Where would you start? What would be your next move if you were asked to find the root cause of this issue? When I ask this question, most people shout out \u201cthe event handler\u201d, meaning that they would start by putting a breakpoint at the first line of code in the event handler of the \u201cSave\u201d button.<\/p>\n

So let\u2019s go ahead and set that breakpoint, scroll the editor to the bottom and make another change:<\/p>\n

\"clip_image005\"<\/p>\n

I click the \u201cSave\u201d button and the debugger breaks at my breakpoint:<\/p>\n

\"clip_image006\"<\/p>\n

None of the event handler\u2019s code has executed yet. Before I step through this code I want to make sure there is nothing obvious that stands out. From experience, many will point out that this.txtFileContents.Focus() looks suspicious, so I\u2019m going to comment that part out (using Edit & Continue<\/a>) and continue stepping:<\/p>\n

\"clip_image007\"<\/p>\n

There were no exceptions thrown and nothing else looks suspicious, so I\u2019m going to press F5 to continue running the app and see if the bug is fixed:<\/p>\n

\"clip_image008\"<\/p>\n

Nope, the editor still scrolls to the top and the bug is still there. Unfortunately I was wrong about the method call I commented out and nothing else stands out. There were also no exceptions thrown, so I no longer think the root cause of this bug is in the event handler of the Save button.<\/p>\n

What next? Where would you look now? When I ask this question, I usually have to wait a little bit, but eventually people start offering clever suggestions such as:<\/p>\n