How do I simulate Text input to a WPF TextBox?

Question

I want to simulate user input to a WPF TextBox. I want to input a character such that the OnPreviewTextInput event is triggered. I tried setting the Text through the Text proper

Answer 1

Another way to do this would be by using WinAPI, SendMessage to be specific:

[DllImport("user32.dll")]
public static extern int SendMessage(IntPtr hWnd, uint Msg, int wParam, int lParam);

Then call it this way, when the focus is on the TextBox:

SendMessage(new WindowInteropHelper(this).Handle, 0x0102, 72, 0)

0x0102 is the constant value for WM_CHAR and 72 is the keycode for H (you can change this accordingly).