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...