Security Test Harness for Rule-Based Filing APIs

Security Test Harness for Rule-Based Filing APIs

Rule-heavy APIs fail in subtle ways: an input passes validation but maps to the wrong branch, or a safe payload leaks restricted fields in edge scenarios. A dedicated security harness prevents these misses.

Step 1: Define adversarial scenario fixtures

{
  "case": "mixed-income-edge",
  "input": {"income_w2": 45000, "crypto_gain": 1200},
  "expect": {"requires_schedule_d": true}
}

Step 2: Add output-field leak checks

def assert_no_sensitive_fields(payload):
    blocked = {"ssn", "bank_account", "full_address"}
    assert blocked.isdisjoint(payload.keys())