Prevent a process from showing any dialogs at all?

Question

On Microsoft Windows (8), I would like to start a process, and prevent it from showing any windows at all. Alternatively, to force-close any windows that are shown. Is there a way to do this?

My application is this: I'm running an automated (nunit) test suite on my continuous integration (teamcity) server. The code under test is also used by an interactive application. Developers occasionally slip in a dialog with a user prompt, without realising what they are doing. This causes the CI process to stop, waiting for user input which never comes. I'd like to be able to dismiss any dialog that appears, or prevent them from being shown.

Even better would be to force an exception at this point, so that the test would also fail.

In my case, this is a C# application, and the dialogs shown are Windows Forms or WPF dialogs.

I did find a couple of similar questions. However each turned out to be solving a slightly different problem.

• Stop a process from showing a window from C# (solves a different problem)
• Preventing blocking dialogs/message boxes/hanging GUI from non-interactive processes on Windows? (promising solution but C++-specific)
• Prevent child process from creating visible windows? (solves a different problem)

Answer 1

Have you considered asking your development team to have a "no dialog" mode of the app for testing purposes? Perhaps if you stopped referring to them as (!!*&%) they would be more inclined to partner with you. ;) Afterall, you do work at the same company on the same product :)

In any case, without a dev-specific solution, consider having a another app (process or thread) that continually sleeps for a few seconds, wakes up and looks for a modal dialog in your application. You can use APIs such as FindWindow to identify when a modal dialog has popped up. (Use Spy++ to get the class name for windows created by MessageBox and CreateDialog APIs).