public void Panel_OnKeyPress_Invoke_CallsKeyPress(KeyPressEventArgs eventArgs) { var control = new SubPanel(); int callCount = 0; KeyPressEventHandler handler = (sender, e) => { Assert.Same(control, sender); Assert.Same(eventArgs, e); callCount++; }; // Call with handler. control.KeyPress += handler; control.OnKeyPress(eventArgs); Assert.Equal(1, callCount); // Remove handler. control.KeyPress -= handler; control.OnKeyPress(eventArgs); Assert.Equal(1, callCount); }