As a matter of fact, there are a couple options.

While not quite exactly what you described, here on webDip under the Help/Donate tab, there's a page called DATC Adjudicator Tests (DATC stand for Diplomacy Adjudicator Test Cases):

http://webdiplomacy.net/datc.php

This shows scenarios from very basic to very complex ways units can move. I used it to help teach myself how the game is supposed to be adjudicated, and if I ever want to double check that a certain move is supposed to resolve a certain way I open it up for confirmation.

In terms of being able to input a set of orders, it sounds like you're describing a sandbox. While we don't have that feature here, that feature does exist on another Diplomacy site:

https://www.backstabbr.com/

I hope this is helpful.

Although the basic movements in Diplomacy is quite simple to understand, when put together it can get quite tricky to work out what will actually happen. I find myself constantly asking what will happen if XYZ. Is there an adjudication scenario tester somewhere in the Internet, where I can input a combination of orders, and see what happens (does it bounce, who moves, who gets dislodged, etc.)