A fake marathon every night

Every night at two in the morning, a marathon happens that no one runs. A full field of invented runners, twenty-five thousand of them on the nights the big race is rehearsed, crosses invented mats. Splits arrive, cheers fly, a leaderboard fills. By 2:40 it is over, and by three the world it happened in has been deleted.

The invented runners are test dataConcept · lights on your maptest dataInvented but realistic data for tests to run against: sample users, plausible records, production-shaped messiness. Never real people’s information, since test worlds rarely have production’s protections.: plausible fakes, with plausible paces and plausibly misspelled names. Never real people. Test environments have fewer locks than production on purpose, so what lives in them must be nothing worth stealing, a rule the Act IV audit will test in person.

The invented mats are a mockConcept · lights on your mapmockA stand-in fake for a real dependency during testing: a pretend payment service that always approves, or always declines, since the unhappy paths need rehearsing too. of the timing vendor’s feed: a pretend feed that emits crossings on cue. Mocks play the roles too expensive or too unruly to cast for real, and they take direction beautifully. Tonight the mock feed sends a perfect race. Tomorrow it can send the mat that goes silent for ninety seconds, on demand, at 2 a.m., with nobody standing on a bridge to see it.

What the night is for

The fraction of the codebase the night’s exams actually exercise is its test coverageConcept · lights on your maptest coverageThe percentage of code exercised by tests. Useful as a flashlight for finding the least-tested corner; dangerous as a target, since a test can execute a line without meaningfully checking it., a number Traversal reads as a flashlight and refuses to worship as a target. A test can touch a line without checking anything true about it. Chasing the number produces exactly such tests, and everyone who has done this learns it the same way.

And minutes after anything new lands in a world, a tiny exam runs that asks almost nothing: smoke testingConcept · lights on your mapsmoke testingA fast sanity pass right after a deploy: does it load, can someone log in, does one core action work. Not thoroughness; aliveness. Named for hardware’s first test: plug it in, watch for smoke.. Does the site load. Can a spectator log in. Does one cheer go through. Thoroughness comes later — this is checking for smoke, named for the hardware era’s first and most honest test. If smoke appears, nothing else that night matters.

A fake race, nightly, forever. Week ten’s real one is three scenes away, and between them stand the humans who sign things.