For business application development, start by writing a high-level simulation of the industry, like maybe Sim-City.

This becomes your test harness.

Plug in any actual app that you're writing, as necessary and appropriate.

As multiple sections of the industry get apps written for them, the harness/simulator provides the "modus-integratus".

Give the simulator to the executives to play with.  As various pieces get written and plugged in, their "playing" becomes real...