Understand the failure.
Verify the repair.
Small, reproducible software failures. The broken implementation, the fix that didn’t work, and the one that passed—preserved together.
Explore the cases ↓How results are verified ↗WHAT THE ARCHIVE CONTAINS
100840 executable cases. 20168 are open.
Every case records the implementation that fails, the fix that did not work, and the repair that passed its checks—with recorded outputs and source hashes. This release adds 100840 cases across 20168 failure mechanisms and 254 domains.
The open tier gives you the failure and the unsuccessful fix for one case in every mechanism. The remaining 80672 cases, 5 variants per mechanism, are member-only: the verified repair, its recorded checks, and the full fixture suite are held in the member archive. Read the methodology ↗
A RECORD OF WHAT WENT WRONG
Browse the archive / 100840
Owner move forbidden during borrow · case 01
The operation returns a result or retained state that violates this contract: A single local object grants either any number of shared borrows or one exclusive borrow. Commands are [operation,token,value]. Reads return the value or denied; writes and acquisitions return booleans. Ownership can move only with no borrows. Moving ownership requires a live object and no shared or exclusive borrows.
Owner move forbidden during borrow · case 02
The operation returns a result or retained state that violates this contract: A single local object grants either any number of shared borrows or one exclusive borrow. Commands are [operation,token,value]. Reads return the value or denied; writes and acquisitions return booleans. Ownership can move only with no borrows. Moving ownership requires a live object and no shared or exclusive borrows.
Owner move forbidden during borrow · case 03
The operation returns a result or retained state that violates this contract: A single local object grants either any number of shared borrows or one exclusive borrow. Commands are [operation,token,value]. Reads return the value or denied; writes and acquisitions return booleans. Ownership can move only with no borrows. Moving ownership requires a live object and no shared or exclusive borrows.
Owner move forbidden during borrow · case 04
The operation returns a result or retained state that violates this contract: A single local object grants either any number of shared borrows or one exclusive borrow. Commands are [operation,token,value]. Reads return the value or denied; writes and acquisitions return booleans. Ownership can move only with no borrows. Moving ownership requires a live object and no shared or exclusive borrows.
Owner move forbidden during borrow · case 05
The operation returns a result or retained state that violates this contract: A single local object grants either any number of shared borrows or one exclusive borrow. Commands are [operation,token,value]. Reads return the value or denied; writes and acquisitions return booleans. Ownership can move only with no borrows. Moving ownership requires a live object and no shared or exclusive borrows.
Listener registration replaces identity · case 01
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Registering an existing identity replaces its event metadata while preserving its registration position.
Listener registration replaces identity · case 02
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Registering an existing identity replaces its event metadata while preserving its registration position.
Listener registration replaces identity · case 03
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Registering an existing identity replaces its event metadata while preserving its registration position.
Listener registration replaces identity · case 04
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Registering an existing identity replaces its event metadata while preserving its registration position.
Listener registration replaces identity · case 05
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Registering an existing identity replaces its event metadata while preserving its registration position.
Listener removal by identity · case 01
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Removing one identity preserves all other listeners, including listeners for the same event.
Listener removal by identity · case 02
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Removing one identity preserves all other listeners, including listeners for the same event.
Listener removal by identity · case 03
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Removing one identity preserves all other listeners, including listeners for the same event.
Listener removal by identity · case 04
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Removing one identity preserves all other listeners, including listeners for the same event.
Listener removal by identity · case 05
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Removing one identity preserves all other listeners, including listeners for the same event.
Listener dispatch snapshot · case 01
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Dispatch membership is captured before callbacks; removals during dispatch do not skip captured callbacks.
Listener dispatch snapshot · case 02
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Dispatch membership is captured before callbacks; removals during dispatch do not skip captured callbacks.
Listener dispatch snapshot · case 03
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Dispatch membership is captured before callbacks; removals during dispatch do not skip captured callbacks.
Listener dispatch snapshot · case 04
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Dispatch membership is captured before callbacks; removals during dispatch do not skip captured callbacks.
Listener dispatch snapshot · case 05
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Dispatch membership is captured before callbacks; removals during dispatch do not skip captured callbacks.
Listener event name filter · case 01
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Only listeners registered for the emitted event run.
Listener event name filter · case 02
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Only listeners registered for the emitted event run.
Listener event name filter · case 03
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Only listeners registered for the emitted event run.
Listener event name filter · case 04
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Only listeners registered for the emitted event run.
Listener event name filter · case 05
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. Only listeners registered for the emitted event run.
Once listener removed before action · case 01
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A once listener is removed before callback actions; a callback may explicitly re-register that identity.
Once listener removed before action · case 02
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A once listener is removed before callback actions; a callback may explicitly re-register that identity.
Once listener removed before action · case 03
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A once listener is removed before callback actions; a callback may explicitly re-register that identity.
Once listener removed before action · case 04
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A once listener is removed before callback actions; a callback may explicitly re-register that identity.
Once listener removed before action · case 05
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A once listener is removed before callback actions; a callback may explicitly re-register that identity.
Listener callback registration · case 01
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A listener installed by a callback starts participating on the next dispatch and uses the action-specified event name.
Listener callback registration · case 02
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A listener installed by a callback starts participating on the next dispatch and uses the action-specified event name.
Listener callback registration · case 03
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A listener installed by a callback starts participating on the next dispatch and uses the action-specified event name.
Listener callback registration · case 04
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A listener installed by a callback starts participating on the next dispatch and uses the action-specified event name.
Listener callback registration · case 05
The operation returns a result or retained state that violates this contract: Listeners have identity, event name, once flag, and registration order. Dispatch uses a snapshot; listener actions remove another listener or add a new one. Return callback identities in invocation order. A listener installed by a callback starts participating on the next dispatch and uses the action-specified event name.
Islice leaves unrequested tail · case 01
The operation returns a result or retained state that violates this contract: Take at most n values from a one-pass iterator and return [taken,unconsumed tail]; taking zero consumes nothing.
Islice leaves unrequested tail · case 02
The operation returns a result or retained state that violates this contract: Take at most n values from a one-pass iterator and return [taken,unconsumed tail]; taking zero consumes nothing.
Islice leaves unrequested tail · case 03
The operation returns a result or retained state that violates this contract: Take at most n values from a one-pass iterator and return [taken,unconsumed tail]; taking zero consumes nothing.
Islice leaves unrequested tail · case 04
The operation returns a result or retained state that violates this contract: Take at most n values from a one-pass iterator and return [taken,unconsumed tail]; taking zero consumes nothing.
Islice leaves unrequested tail · case 05
The operation returns a result or retained state that violates this contract: Take at most n values from a one-pass iterator and return [taken,unconsumed tail]; taking zero consumes nothing.
Takewhile consumes first failure · case 01
The operation returns a result or retained state that violates this contract: Consume the prefix before sentinel, consuming but excluding the first sentinel; return [prefix,remainder].
Takewhile consumes first failure · case 02
The operation returns a result or retained state that violates this contract: Consume the prefix before sentinel, consuming but excluding the first sentinel; return [prefix,remainder].
Takewhile consumes first failure · case 03
The operation returns a result or retained state that violates this contract: Consume the prefix before sentinel, consuming but excluding the first sentinel; return [prefix,remainder].
Takewhile consumes first failure · case 04
The operation returns a result or retained state that violates this contract: Consume the prefix before sentinel, consuming but excluding the first sentinel; return [prefix,remainder].
Takewhile consumes first failure · case 05
The operation returns a result or retained state that violates this contract: Consume the prefix before sentinel, consuming but excluding the first sentinel; return [prefix,remainder].
Dropwhile stops testing after first failure · case 01
The operation returns a result or retained state that violates this contract: Drop an initial run of sentinel values; once a non-sentinel appears, retain the entire suffix including later sentinels.
Dropwhile stops testing after first failure · case 02
The operation returns a result or retained state that violates this contract: Drop an initial run of sentinel values; once a non-sentinel appears, retain the entire suffix including later sentinels.
Dropwhile stops testing after first failure · case 03
The operation returns a result or retained state that violates this contract: Drop an initial run of sentinel values; once a non-sentinel appears, retain the entire suffix including later sentinels.
Dropwhile stops testing after first failure · case 04
The operation returns a result or retained state that violates this contract: Drop an initial run of sentinel values; once a non-sentinel appears, retain the entire suffix including later sentinels.
Dropwhile stops testing after first failure · case 05
The operation returns a result or retained state that violates this contract: Drop an initial run of sentinel values; once a non-sentinel appears, retain the entire suffix including later sentinels.
Compress consumes one extra data item · case 01
The operation returns a result or retained state that violates this contract: Use itertools compress semantics: consume one data item before discovering selectors are exhausted; return [selected,data remainder].
Compress consumes one extra data item · case 02
The operation returns a result or retained state that violates this contract: Use itertools compress semantics: consume one data item before discovering selectors are exhausted; return [selected,data remainder].
Compress consumes one extra data item · case 03
The operation returns a result or retained state that violates this contract: Use itertools compress semantics: consume one data item before discovering selectors are exhausted; return [selected,data remainder].
Compress consumes one extra data item · case 04
The operation returns a result or retained state that violates this contract: Use itertools compress semantics: consume one data item before discovering selectors are exhausted; return [selected,data remainder].
Compress consumes one extra data item · case 05
The operation returns a result or retained state that violates this contract: Use itertools compress semantics: consume one data item before discovering selectors are exhausted; return [selected,data remainder].
Filterfalse inverts predicate · case 01
The operation returns a result or retained state that violates this contract: Retain values unequal to the sentinel, including other falsy values.
Filterfalse inverts predicate · case 02
The operation returns a result or retained state that violates this contract: Retain values unequal to the sentinel, including other falsy values.
Filterfalse inverts predicate · case 03
The operation returns a result or retained state that violates this contract: Retain values unequal to the sentinel, including other falsy values.
Filterfalse inverts predicate · case 04
The operation returns a result or retained state that violates this contract: Retain values unequal to the sentinel, including other falsy values.
Filterfalse inverts predicate · case 05
The operation returns a result or retained state that violates this contract: Retain values unequal to the sentinel, including other falsy values.
Chain drains current before next · case 01
The operation returns a result or retained state that violates this contract: Flatten exactly one iterable level in outer order, retaining empty and nested values at deeper levels.
Chain drains current before next · case 02
The operation returns a result or retained state that violates this contract: Flatten exactly one iterable level in outer order, retaining empty and nested values at deeper levels.
Chain drains current before next · case 03
The operation returns a result or retained state that violates this contract: Flatten exactly one iterable level in outer order, retaining empty and nested values at deeper levels.
Chain drains current before next · case 04
The operation returns a result or retained state that violates this contract: Flatten exactly one iterable level in outer order, retaining empty and nested values at deeper levels.
Chain drains current before next · case 05
The operation returns a result or retained state that violates this contract: Flatten exactly one iterable level in outer order, retaining empty and nested values at deeper levels.
Groupby adjacency not global key · case 01
The operation returns a result or retained state that violates this contract: Group consecutive equal values into [key,group] pairs; separated equal runs remain separate.
Groupby adjacency not global key · case 02
The operation returns a result or retained state that violates this contract: Group consecutive equal values into [key,group] pairs; separated equal runs remain separate.
Groupby adjacency not global key · case 03
The operation returns a result or retained state that violates this contract: Group consecutive equal values into [key,group] pairs; separated equal runs remain separate.
Groupby adjacency not global key · case 04
The operation returns a result or retained state that violates this contract: Group consecutive equal values into [key,group] pairs; separated equal runs remain separate.
Groupby adjacency not global key · case 05
The operation returns a result or retained state that violates this contract: Group consecutive equal values into [key,group] pairs; separated equal runs remain separate.
Groupby materialize before advancing · case 01
The operation returns a result or retained state that violates this contract: Materialize each group before advancing the outer group iterator, since group iterators share their source.
Groupby materialize before advancing · case 02
The operation returns a result or retained state that violates this contract: Materialize each group before advancing the outer group iterator, since group iterators share their source.
Groupby materialize before advancing · case 03
The operation returns a result or retained state that violates this contract: Materialize each group before advancing the outer group iterator, since group iterators share their source.
Groupby materialize before advancing · case 04
The operation returns a result or retained state that violates this contract: Materialize each group before advancing the outer group iterator, since group iterators share their source.
Groupby materialize before advancing · case 05
The operation returns a result or retained state that violates this contract: Materialize each group before advancing the outer group iterator, since group iterators share their source.
Tee branches have independent cursors · case 01
The operation returns a result or retained state that violates this contract: Advance the first tee branch n positions; the second still yields the entire original stream.
Tee branches have independent cursors · case 02
The operation returns a result or retained state that violates this contract: Advance the first tee branch n positions; the second still yields the entire original stream.
Tee branches have independent cursors · case 03
The operation returns a result or retained state that violates this contract: Advance the first tee branch n positions; the second still yields the entire original stream.
Tee branches have independent cursors · case 04
The operation returns a result or retained state that violates this contract: Advance the first tee branch n positions; the second still yields the entire original stream.
Tee branches have independent cursors · case 05
The operation returns a result or retained state that violates this contract: Advance the first tee branch n positions; the second still yields the entire original stream.
Cycle caches entire first pass · case 01
The operation returns a result or retained state that violates this contract: Emit n cyclic values from a finite input, or no values for empty input.
Cycle caches entire first pass · case 02
The operation returns a result or retained state that violates this contract: Emit n cyclic values from a finite input, or no values for empty input.
Cycle caches entire first pass · case 03
The operation returns a result or retained state that violates this contract: Emit n cyclic values from a finite input, or no values for empty input.
Cycle caches entire first pass · case 04
The operation returns a result or retained state that violates this contract: Emit n cyclic values from a finite input, or no values for empty input.
Cycle caches entire first pass · case 05
The operation returns a result or retained state that violates this contract: Emit n cyclic values from a finite input, or no values for empty input.
Repeat retains object identity · case 01
The operation returns a result or retained state that violates this contract: Repeat one mutable list n times, mutate its first repeated reference, and report all repetitions; they alias the same object.
Repeat retains object identity · case 02
The operation returns a result or retained state that violates this contract: Repeat one mutable list n times, mutate its first repeated reference, and report all repetitions; they alias the same object.
Repeat retains object identity · case 03
The operation returns a result or retained state that violates this contract: Repeat one mutable list n times, mutate its first repeated reference, and report all repetitions; they alias the same object.
Repeat retains object identity · case 04
The operation returns a result or retained state that violates this contract: Repeat one mutable list n times, mutate its first repeated reference, and report all repetitions; they alias the same object.
Repeat retains object identity · case 05
The operation returns a result or retained state that violates this contract: Repeat one mutable list n times, mutate its first repeated reference, and report all repetitions; they alias the same object.
Product zero inputs has empty tuple · case 01
The operation returns a result or retained state that violates this contract: Compute the Cartesian product of the supplied pools, yielding one empty tuple for zero pools.
Product zero inputs has empty tuple · case 02
The operation returns a result or retained state that violates this contract: Compute the Cartesian product of the supplied pools, yielding one empty tuple for zero pools.
Product zero inputs has empty tuple · case 03
The operation returns a result or retained state that violates this contract: Compute the Cartesian product of the supplied pools, yielding one empty tuple for zero pools.
Product zero inputs has empty tuple · case 04
The operation returns a result or retained state that violates this contract: Compute the Cartesian product of the supplied pools, yielding one empty tuple for zero pools.
Product zero inputs has empty tuple · case 05
The operation returns a result or retained state that violates this contract: Compute the Cartesian product of the supplied pools, yielding one empty tuple for zero pools.
Permutations use positions not distinct values · case 01
The operation returns a result or retained state that violates this contract: Return ordered length-r permutations of distinct input positions; equal values may produce equal output tuples.
Permutations use positions not distinct values · case 02
The operation returns a result or retained state that violates this contract: Return ordered length-r permutations of distinct input positions; equal values may produce equal output tuples.
Permutations use positions not distinct values · case 03
The operation returns a result or retained state that violates this contract: Return ordered length-r permutations of distinct input positions; equal values may produce equal output tuples.
Permutations use positions not distinct values · case 04
The operation returns a result or retained state that violates this contract: Return ordered length-r permutations of distinct input positions; equal values may produce equal output tuples.
Permutations use positions not distinct values · case 05
The operation returns a result or retained state that violates this contract: Return ordered length-r permutations of distinct input positions; equal values may produce equal output tuples.
INSPECTABLE BY DESIGN
Every result has a runnable source.
Runnable implementations with recorded outputs, source hashes, and explicit contracts. Related variants share a failure mechanism and belong together in evaluation splits.
Read the methodology ↗