Test the first move in the first example play, failing build/test - Red
Added stub ExecutePlayerCommand() and enum for commands. - still Red

Build succeeds, tests fail
Using the ubiquitous language of the domain :-)
 - player moves are "commands" to avoid confusion with Move the command!
Nice errors for wrong player move test
US12345 - Implemented player move feature. Tests pass - Green

^ user story would go here In Real Life