Programmatically generate keydown presses for WPF unit tests

You can extend the PresentationSource class like this:

public class FakePresentationSource : PresentationSource{    protected override CompositionTarget GetCompositionTargetCore()    {        return null;    }    public override Visual RootVisual { get; set; }    public override bool IsDisposed { get { return false; } }}

And use it like this:

var uiElement = new UIElement();uiElement.RaiseEvent(new KeyEventArgs(Keyboard.PrimaryDevice, new FakePresentationSource(), 0, Key.Delete) {     RoutedEvent = UIElement.KeyDownEvent });

A quicker solution for unit tests is just to mock the PresentationSource object. Note that it requires an STA thread. Sample uses Moq and nunit.

[Test][RequiresSTA]public void test_something(){  new KeyEventArgs(    Keyboard.PrimaryDevice,    new Mock<PresentationSource>().Object,    0,    Key.Back);}

Figured this out after reading this post.

Basically, you need to put your control inside a Window and call Window.Show() on it. The post mentioned an WPF bug, but I didn't encounter this in WPF 4.

After calling Window.Show(), the presentation source will no longer be null and you will be able to send keys to the control.