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code-coverage

  • Ten years of a codebase, read in one week

    Deep dive10 min read

    A decade of an application, and a week spent reading it rather than changing it. Decisions re-litigated because nobody knows what is already there.

  • A test suite that runs on every commit, in ninety seconds

    Deep dive9 min read

    Four minutes forty is fine and ninety seconds changes behaviour. The threshold below which running the suite stops being a decision.

  • A year of an assistant in the editor, measured

    Deep dive14 min read

    A year of using a model-backed assistant, and an attempt to say something specific about it. Every claim about this is a demonstration or a complaint.

  • A pipeline that deploys on merge, and the four gates before it

    Deep dive10 min read

    Eight deploys a week performed by a person, an hour after merge, by whoever was free. Continuous deployment needs confidence rather than automation.

  • 188 tests deleted with the code they covered

    Note2 min read

    A directory of tests excluded from every tool since 2023, examined and removed along with what they tested. Three independent checks — coverage to find what the tests…

  • PHPUnit 12, and the tests we deleted instead

    Deep dive9 min read

    A two-hour upgrade, and a directory of 188 tests excluded from every tool since 2023 and running on every push.

  • The snapshot I approved without reading

    Note2 min read

    A snapshot test that failed, an approval taken on the basis that the change was intentional, and a diff nobody opened. A snapshot test moves the verification from…

  • Mutation testing on a second directory

    Note2 min read

    A technique applied to one directory in 2023, extended to a second, with a much worse result and a better reason. A low score on code that implements…

  • Sampling a generated diff, and what sample size means

    Note2 min read

    An automated refactor across four hundred files, and a review that cannot read eight thousand lines. Splitting the run by rule and reviewing each separately is what makes…

  • A coverage driver change that broke one CI image

    Note1 min read

    PHPUnit 11 dropping support for one coverage driver, on a CI image that had it and not the other. The upgrade forced a change that was overdue for…