blog: nobody's example - #874
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Twelfth post in the CI-gates series, and the one the closed mutation line was for. A gate's negative control is written by someone who plants the fault it is meant to catch -- which is by construction a non-degenerate example: a file with the wrong contents, not a file with no contents. The empty case, the equal case and the one-off-the-edge case are examples of nothing, so no author reaches for them, so no control contains them, so every comparison is free to sit one place off and pass. That is the whole yield of the boundary operator: 12 survivors on its first honest run, in a suite three other operators had already scoured. Six closed in one pass and every one needed a degenerate input. Includes the one with teeth -- a guard whose mutant reports an already-empty file as newly emptied on every run forever, which is a permanent false alarm rather than a missed failure, and the failure mode that gets a gate switched off. Both locales. Three receipts. Four open questions, including that the degeneracy explanation is an argument from six cases in one repository and predicts a hole it does not measure elsewhere.
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blog: nobody's example (#874) Twelfth post in the CI-gates series, and the one the closed mutation line was for. A gate's negative control is written by someone who plants the fault it is meant to catch -- which is by construction a non-degenerate example: a file with the wrong contents, not a file with no contents. The empty case, the equal case and the one-off-the-edge case are examples of nothing, so no author reaches for them, so no control contains them, so every comparison is free to sit one place off and pass. That is the whole yield of the boundary operator: 12 survivors on its first honest run, in a suite three other operators had already scoured. Six closed in one pass and every one needed a degenerate input. Includes the one with teeth -- a guard whose mutant reports an already-empty file as newly emptied on every run forever, which is a permanent false alarm rather than a missed failure, and the failure mode that gets a gate switched off. Both locales. Three receipts. Four open questions, including that the degeneracy explanation is an argument from six cases in one repository and predicts a hole it does not measure elsewhere.
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Twelfth post in the CI-gates series, and the one the closed mutation line was for.
A gate's negative control is written by someone who plants the fault it is meant to catch — which is by construction a non-degenerate example: a file with the wrong contents, not a file with no contents. The empty case, the equal case and the one-off-the-edge case are examples of nothing, so no author reaches for them, so no control contains them, so every comparison in the gate is free to sit one place off and pass.
That is the entire yield of the boundary operator — twelve survivors on its first honest run, in a suite three other operators had already scoured. Six closed in one pass and every one of them needed a degenerate input.
Includes the one with teeth: a guard whose mutant announces an already-empty file as newly emptied on every run, forever. Not a missed failure — a permanent false alarm, which is the failure mode that gets a gate switched off, and after that it misses everything.
Also covered: how one planted tree closes two boundaries when they are the same expression read on both sides of a ledger; why "cosmetic" was closed rather than declared, twice; and the two remaining survivors, which are proven equivalences whose proof was sitting two lines above the comparison the whole time.
Both locales. Three receipts. Four open questions — including that the degeneracy explanation is an argument from six cases in one repository, and predicts a hole in other suites that it does not measure.