#refactoring

Map Every Changed Line to the Test That Ran It Before You Refactor Start with the...

An agent extracts a duplicated upstream-call block into a shared helper and merges two divergent error paths: a caller that needed to rethrow now serves a degraded fallback. Green tests pass because only the happy caller was retested. Covers auditing a refactor against each caller's fault behavior.

Most refactors keep the happy path intact. They quietly rewrite the error path. Messages get...

Return values pass. Side effects drift. That is the refactor bug your tests never catch. A...

Return values are the easy part of a refactor. Side-effect order is where messy repos break...

A golden test that passes once proves almost nothing. It proves the harness ran. The second run is...

A shipping-cost module has twelve tests, all passing, and a refactor that looks mechanical. Someone...

A green characterization suite proves very little. It proves the tests ran once against current...

A passing test suite can hide a refactor bug for months. That happens when the tests assert nothing...

A green characterization suite proves agreement, not coverage. Your assertions may be broad enough to...

A return-value assertion will not catch a moved webhook. In a messy repo, the cheapest safety net is...

One feature, six names, and the only one that mentions a file format names a file format no code in the repository produces. Grep for "csv" in our codebase and you get two hits, one of which is a comment explaining why there are no others.