How to press the mouse and drag during the test?

In a play mode test I am able to effectively click on items. In some cases I need to drag an item. My first test is actually a scrollview panel that the mouse can move with the left button press and drag. I would have thought you just do the following (assumes the scroll surface is visible at 10,10):

Code (CSharp):

1. Set(mouse.position, new Vector2(10,10));
2. Press(mouse.leftButton);
3. yield return new WaitForSeconds(0.1f);
4. InputSystem.Update();
5. Set(mouse.position, new Vector2(1000,10));
6. Release(mouse.leftButton);
7. yield return new WaitForSeconds(0.1f);

I can debug and see the mouse down/up occurs, and there was a value for delta. Yet the scroll panel does not move. I was able to make the panel move with:

Code (CSharp):

1. Set(mouse.scroll, new Vector2(7000,100));
2. yield return new WaitForSeconds(0.1f);

So it's functional. Unfortunately I have items that are actual drag and drop. I have yet to find any example how this is properly done as a test. Anyone have a working sample?