In 30 seconds

The happy path usually works. Failures cluster in the edges: unusual formats, missing information, conflicting data, and inputs the AI should refuse. Test those on purpose, because they are exactly what a demo skips.

Why this comes up

It is natural to test with clean, typical cases, and they usually pass. But real work is full of edges, and that is where an AI workflow quietly breaks. If you only test the easy cases, you learn nothing about the cases that will actually cause problems.

The edge cases worth testing

Unusual inputs

Odd formats, unexpected structure, very long or very short inputs, foreign languages, poor scans. These stress the interpretation step where AI is weakest.

Missing information

Cases where a required field is absent or empty. Does the workflow notice, or does it invent a value and carry on? An AI that fills a gap confidently is dangerous.

Conflicting information

Cases where sources or fields disagree. Does the workflow catch the conflict, or silently pick one? See how to handle conflicting sources.

Prohibited and out-of-scope cases

Inputs the AI should not act on: requests outside its job, actions it is not allowed to take. Test that it refuses or escalates rather than proceeding. This overlaps with testing permission boundaries.

Draw edge cases from real work

The best edge cases are real ones you have seen, not invented extremes. Your discovery work, especially finding hidden steps and exceptions, is a rich source. Add every real failure you discover to your test set so it is checked forever after.

A small example

An extraction workflow passed every clean invoice. Testing edge cases revealed it confidently invented a total when the amount field was missing, and happily processed a document that was not an invoice at all. Both were quick to fix once found, and disastrous if they had reached production unseen.

What this does not solve

Edge-case testing catches the failure modes you think to test; it cannot anticipate every one. New edges will appear in real use. Treat edge testing as ongoing: keep adding cases from real operation, not just from the initial build.

Good enough to move on when

  • You have tested unusual, missing and conflicting inputs.
  • Prohibited and out-of-scope cases are tested and refused.
  • The workflow escalates rather than guessing on hard cases.
  • Real failures are added to the test set.