UAT vs SIT testing in Oracle Fusion — what implementation teams get wrong

SIT and UAT get lumped together a lot, and honestly, on smaller projects people sometimes skip straight from one to the other without really separating the two. That's usually where trouble starts.

SIT (System Integration Testing) is about making sure the pieces of the system talk to each other correctly — Fusion talking to your third-party payroll system, or SCM talking to a warehouse management tool, that kind of thing. It's technical, it's about data flowing correctly end to end, and it's usually owned by the implementation/technical team.

UAT (User Acceptance Testing) is a completely different animal. This is where actual business users — the finance team, the procurement team, whoever — sit down and confirm the system actually does what they need it to do in their day-to-day work. It's less about "does the integration work" and more about "can I actually close the books with this."

The mistake a lot of implementation teams make is treating UAT like a second round of SIT. They hand business users a script to follow step by step, which defeats the point. UAT should surface real gaps — the process that technically works but doesn't match how the business actually operates.

The other mistake: not leaving enough time between SIT and UAT to fix what SIT found. Teams get squeezed on timelines and end up running UAT on a system that hasn't stabilized yet, which just erodes user confidence before go-live.

If there's one thing worth protecting on your project timeline, it's the gap between these two phases. Rushing it rarely ends well.