Held the generator to 964 test cases at a 92% branch‑coverage floor with warnings treated as failures, and asserted idempotence by running the whole build pipeline twice from an empty file and requiring the second pass to change nothing.

Situation. A generator that assembles a database from scratch has a particular kind of bug: it works the first time and corrupts the second. Steps that insert without checking, steps that depend on the order of a previous step’s output, steps that are safe alone and not together. None of that shows up in a test that starts from nothing and runs once.

Task. The build had to be proved repeatable rather than merely working, and the test suite had to be large enough and strict enough that a regression could not pass through it quietly.

Action. The idempotence test is the blunt one and the most useful: build the entire database from an empty file, snapshot it, run the whole eighteen‑step pipeline again over the result, and require the second pass to change nothing. Row counts, contents and identifiers all have to match. Around it sit 373 test functions – 964 cases once the parameterised ones expand – across forty‑four files and 7,750 lines, covering the pipeline, the renderers, the content loaders, the targeting logic and the checkers. Branch coverage carries a floor of ninety‑two percent enforced in the build rather than reported in a summary, and the suite currently measures about 95 percent, so the floor has headroom without being decorative. Warnings are configured as failures, which is the setting that matters most in practice — a deprecation notice that prints for two years is a deprecation notice nobody reads, and the run that turns it into a red test is the run that gets it fixed.

Result. The pipeline can be re‑run against a live database without fear, which is what makes incremental content work possible at all. The floor is a floor, not a target, and it is worth saying that ninety‑two percent branch coverage still leaves branches nothing has ever taken — the number bounds the risk, it does not remove it, and two of the defects found later in the project were in code the coverage report showed as covered.