Test-Driven Investigation

Overview

When investigating a bug, write a reproducing test as early as possible. Analysis without experimentation spirals into circular reasoning.

Core principle: A 20-line test that fails tells you more than 2 hours of reading source code.

The Anti-Pattern

READ code → BUILD mental model → READ more code → REVISE model → READ more code →
SECOND-GUESS model → READ same code again → ... → eventually write a test

This feels productive but isn't. You're pattern-matching on code without grounding in reality. Each re-read adds uncertainty, not clarity.

The Pattern