Testing Illusions – AI‑Generated Tests That Lie

Introduction AI can generate tests quickly, but quantity doesn’t equal quality. Many AI‑generated tests either assert the wrong thing, miss edge cases, or are not idempotent. This post shows you five testing pitfalls and how to prompt for meaningful test suites. Mistake 1: AI Generates Tests That Pass Incorrectly Description: AI generates tests that assert incorrect expected values, passing but not validating actual behavior. Realistic Scenario: AI generates test for calculator that expects wrong result but test passes. ❌ Wrong Prompt: Write tests for add function ⚠️ Why it is wrong: AI may generate assertEquals(3, add(1, 1)) expecting 3 when correct result is 2, test passes but validation fails. ✅ Better Prompt: Write tests for add(int a, int b) function with verification. Requirements: Test with known inputs: (1,1)=2, (-1,1)=0, (0,0)=0 Test boundary: Integer.MAX_VALUE + 1 Verify actual result matches expected Use parameterized tests to avoid duplication Include property-based tests f