testkit

The suite you build for code that already works. testkit reads a codebase with no tests, or a handful of stale ones, ranks what is worth covering, crowns one slice, and writes tests that have each been observed to fail before they were kept.

Two modes. audit ranks the untested surface and writes nothing but a ledger. cover writes the tests.

The failure it exists to prevent

An agent asked to "write tests for this project" reliably produces coverage theater: a pile of tests that mirror the implementation line for line, assert that mocks were called, pass on the first run, and pin whatever the code does today, bugs included.

It looks exactly like a real suite. Same layout, same green checkmarks, same coverage number. It is worse than no suite, because it charges maintenance rent forever, detects nothing, and hands you a green checkmark that is now evidence in arguments it cannot support.

Two properties separate a real brownfield test from that pile, and both are structurally absent unless you force them:

1. The test has been watched to fail. Code written before the test means red-then-green never happens on its own. The failure has to be manufactured deliberately, or it does not happen at all.
2. The expectation came from outside the implementation. A test whose expected value was read off the function it tests is a photograph of current behaviour, not a claim about correct behaviour.

Every rule below exists to make those two mandatory rather than aspirational.