Report: reproduction info (seed/size/index) and replay of a single case #7

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opened 2026-09-13 21:24:22 +09:00 by natsukium · 1 comment

natsukium commented

2026-09-13 21:24:22 +09:00

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Missing

Enough information in a failing Report to reproduce the case, and a way to re-run exactly that case.

Why

failure carries original / shrunk / shrinkSteps but not the seed, size or index that produced it. A counterexample seen in CI cannot be replayed locally without re-running the whole suite with the same seed and hoping it is deterministic. Hedgehog has recheck size seed, fast-check reports { seed, path }, Hypothesis has @reproduce_failure.

Suggested shape

failure gains seed, size, index (position in the run).
check { replay = { seed; size; }; } (or recheck) runs the single case and shrinks it.
Falls out of the loop refactor planned for #1: once cases opts gen yields { tree; size; index; } the runner only has to keep them.

## Missing Enough information in a failing `Report` to reproduce the case, and a way to re-run exactly that case. ## Why `failure` carries `original` / `shrunk` / `shrinkSteps` but not the seed, size or index that produced it. A counterexample seen in CI cannot be replayed locally without re-running the whole suite with the same seed and hoping it is deterministic. Hedgehog has `recheck size seed`, fast-check reports `{ seed, path }`, Hypothesis has `@reproduce_failure`. ## Suggested shape - `failure` gains `seed`, `size`, `index` (position in the run). - `check { replay = { seed; size; }; }` (or `recheck`) runs the single case and shrinks it. - Falls out of the loop refactor planned for #1: once `cases opts gen` yields `{ tree; size; index; }` the runner only has to keep them.

natsukium referenced this issue

2026-09-13 21:24:52 +09:00

sample: draw n values from a generator without running a property #1

natsukium commented

2026-09-14 00:44:14 +09:00

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Implemented in 1ef73bd, pushed to main.

Implemented in 1ef73bd, pushed to main.

natsukium closed this issue

2026-09-14 00:44:14 +09:00