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
Suffix empty identity · case 01
The operation returns a result or retained state that violates this contract: Return whether right is a positional suffix of left, with empty right always matching.
Suffix empty identity · case 02
The operation returns a result or retained state that violates this contract: Return whether right is a positional suffix of left, with empty right always matching.
Suffix empty identity · case 03
The operation returns a result or retained state that violates this contract: Return whether right is a positional suffix of left, with empty right always matching.
Suffix empty identity · case 04
The operation returns a result or retained state that violates this contract: Return whether right is a positional suffix of left, with empty right always matching.
Suffix empty identity · case 05
The operation returns a result or retained state that violates this contract: Return whether right is a positional suffix of left, with empty right always matching.
Disjointness ignores order · case 01
The operation returns a result or retained state that violates this contract: Return true exactly when the operands share no value.
Disjointness ignores order · case 02
The operation returns a result or retained state that violates this contract: Return true exactly when the operands share no value.
Disjointness ignores order · case 03
The operation returns a result or retained state that violates this contract: Return true exactly when the operands share no value.
Disjointness ignores order · case 04
The operation returns a result or retained state that violates this contract: Return true exactly when the operands share no value.
Disjointness ignores order · case 05
The operation returns a result or retained state that violates this contract: Return true exactly when the operands share no value.
Multiset subset respects counts · case 01
The operation returns a result or retained state that violates this contract: Return whether every left occurrence can be matched to a distinct equal right occurrence.
Multiset subset respects counts · case 02
The operation returns a result or retained state that violates this contract: Return whether every left occurrence can be matched to a distinct equal right occurrence.
Multiset subset respects counts · case 03
The operation returns a result or retained state that violates this contract: Return whether every left occurrence can be matched to a distinct equal right occurrence.
Multiset subset respects counts · case 04
The operation returns a result or retained state that violates this contract: Return whether every left occurrence can be matched to a distinct equal right occurrence.
Multiset subset respects counts · case 05
The operation returns a result or retained state that violates this contract: Return whether every left occurrence can be matched to a distinct equal right occurrence.
Sequence equality retains order · case 01
The operation returns a result or retained state that violates this contract: Return true only when both lists have the same values at the same positions.
Sequence equality retains order · case 02
The operation returns a result or retained state that violates this contract: Return true only when both lists have the same values at the same positions.
Sequence equality retains order · case 03
The operation returns a result or retained state that violates this contract: Return true only when both lists have the same values at the same positions.
Sequence equality retains order · case 04
The operation returns a result or retained state that violates this contract: Return true only when both lists have the same values at the same positions.
Sequence equality retains order · case 05
The operation returns a result or retained state that violates this contract: Return true only when both lists have the same values at the same positions.
Bag equality retains counts · case 01
The operation returns a result or retained state that violates this contract: Return true for equal occurrence counts regardless of positional order.
Bag equality retains counts · case 02
The operation returns a result or retained state that violates this contract: Return true for equal occurrence counts regardless of positional order.
Bag equality retains counts · case 03
The operation returns a result or retained state that violates this contract: Return true for equal occurrence counts regardless of positional order.
Bag equality retains counts · case 04
The operation returns a result or retained state that violates this contract: Return true for equal occurrence counts regardless of positional order.
Bag equality retains counts · case 05
The operation returns a result or retained state that violates this contract: Return true for equal occurrence counts regardless of positional order.
Set equality ignores counts · case 01
The operation returns a result or retained state that violates this contract: Return true for equal member sets regardless of counts and order.
Set equality ignores counts · case 02
The operation returns a result or retained state that violates this contract: Return true for equal member sets regardless of counts and order.
Set equality ignores counts · case 03
The operation returns a result or retained state that violates this contract: Return true for equal member sets regardless of counts and order.
Set equality ignores counts · case 04
The operation returns a result or retained state that violates this contract: Return true for equal member sets regardless of counts and order.
Set equality ignores counts · case 05
The operation returns a result or retained state that violates this contract: Return true for equal member sets regardless of counts and order.
List insert clamps negative index · case 01
The operation returns a result or retained state that violates this contract: Insert a value using Python positional insertion: negative offsets are relative to length and clamp at zero.
List insert clamps negative index · case 02
The operation returns a result or retained state that violates this contract: Insert a value using Python positional insertion: negative offsets are relative to length and clamp at zero.
List insert clamps negative index · case 03
The operation returns a result or retained state that violates this contract: Insert a value using Python positional insertion: negative offsets are relative to length and clamp at zero.
List insert clamps negative index · case 04
The operation returns a result or retained state that violates this contract: Insert a value using Python positional insertion: negative offsets are relative to length and clamp at zero.
List insert clamps negative index · case 05
The operation returns a result or retained state that violates this contract: Insert a value using Python positional insertion: negative offsets are relative to length and clamp at zero.
List remove first equal only · case 01
The operation returns a result or retained state that violates this contract: Remove the first equal value, leaving later equal occurrences intact; missing value is a no-op.
List remove first equal only · case 02
The operation returns a result or retained state that violates this contract: Remove the first equal value, leaving later equal occurrences intact; missing value is a no-op.
List remove first equal only · case 03
The operation returns a result or retained state that violates this contract: Remove the first equal value, leaving later equal occurrences intact; missing value is a no-op.
List remove first equal only · case 04
The operation returns a result or retained state that violates this contract: Remove the first equal value, leaving later equal occurrences intact; missing value is a no-op.
List remove first equal only · case 05
The operation returns a result or retained state that violates this contract: Remove the first equal value, leaving later equal occurrences intact; missing value is a no-op.
List replace one index · case 01
The operation returns a result or retained state that violates this contract: Replace exactly the selected valid positional item, not every equal item.
List replace one index · case 02
The operation returns a result or retained state that violates this contract: Replace exactly the selected valid positional item, not every equal item.
List replace one index · case 03
The operation returns a result or retained state that violates this contract: Replace exactly the selected valid positional item, not every equal item.
List replace one index · case 04
The operation returns a result or retained state that violates this contract: Replace exactly the selected valid positional item, not every equal item.
List replace one index · case 05
The operation returns a result or retained state that violates this contract: Replace exactly the selected valid positional item, not every equal item.
List splice replaces range · case 01
The operation returns a result or retained state that violates this contract: Replace the half-open positional slice with all supplied elements, allowing length changes.
List splice replaces range · case 02
The operation returns a result or retained state that violates this contract: Replace the half-open positional slice with all supplied elements, allowing length changes.
List splice replaces range · case 03
The operation returns a result or retained state that violates this contract: Replace the half-open positional slice with all supplied elements, allowing length changes.
List splice replaces range · case 04
The operation returns a result or retained state that violates this contract: Replace the half-open positional slice with all supplied elements, allowing length changes.
List splice replaces range · case 05
The operation returns a result or retained state that violates this contract: Replace the half-open positional slice with all supplied elements, allowing length changes.
List pop returns value and remainder · case 01
The operation returns a result or retained state that violates this contract: Pop a valid index and return [removed value, remaining list].
List pop returns value and remainder · case 02
The operation returns a result or retained state that violates this contract: Pop a valid index and return [removed value, remaining list].
List pop returns value and remainder · case 03
The operation returns a result or retained state that violates this contract: Pop a valid index and return [removed value, remaining list].
List pop returns value and remainder · case 04
The operation returns a result or retained state that violates this contract: Pop a valid index and return [removed value, remaining list].
List pop returns value and remainder · case 05
The operation returns a result or retained state that violates this contract: Pop a valid index and return [removed value, remaining list].
Extended slice assignment stride · case 01
The operation returns a result or retained state that violates this contract: Replace values at the selected positive stride positions; replacement length matches selected length.
Extended slice assignment stride · case 02
The operation returns a result or retained state that violates this contract: Replace values at the selected positive stride positions; replacement length matches selected length.
Extended slice assignment stride · case 03
The operation returns a result or retained state that violates this contract: Replace values at the selected positive stride positions; replacement length matches selected length.
Extended slice assignment stride · case 04
The operation returns a result or retained state that violates this contract: Replace values at the selected positive stride positions; replacement length matches selected length.
Extended slice assignment stride · case 05
The operation returns a result or retained state that violates this contract: Replace values at the selected positive stride positions; replacement length matches selected length.
Slice deletion does not shift followup indices · case 01
The operation returns a result or retained state that violates this contract: Delete all original positions selected by a positive stride in one operation.
Slice deletion does not shift followup indices · case 02
The operation returns a result or retained state that violates this contract: Delete all original positions selected by a positive stride in one operation.
Slice deletion does not shift followup indices · case 03
The operation returns a result or retained state that violates this contract: Delete all original positions selected by a positive stride in one operation.
Slice deletion does not shift followup indices · case 04
The operation returns a result or retained state that violates this contract: Delete all original positions selected by a positive stride in one operation.
Slice deletion does not shift followup indices · case 05
The operation returns a result or retained state that violates this contract: Delete all original positions selected by a positive stride in one operation.
List append keeps nested value · case 01
The operation returns a result or retained state that violates this contract: Append the provided value as one item, even if it is a list.
List append keeps nested value · case 02
The operation returns a result or retained state that violates this contract: Append the provided value as one item, even if it is a list.
List append keeps nested value · case 03
The operation returns a result or retained state that violates this contract: Append the provided value as one item, even if it is a list.
List append keeps nested value · case 04
The operation returns a result or retained state that violates this contract: Append the provided value as one item, even if it is a list.
List append keeps nested value · case 05
The operation returns a result or retained state that violates this contract: Append the provided value as one item, even if it is a list.
List extend expands one level · case 01
The operation returns a result or retained state that violates this contract: Extend by the iterable elements, without recursively flattening nested elements.
List extend expands one level · case 02
The operation returns a result or retained state that violates this contract: Extend by the iterable elements, without recursively flattening nested elements.
List extend expands one level · case 03
The operation returns a result or retained state that violates this contract: Extend by the iterable elements, without recursively flattening nested elements.
List extend expands one level · case 04
The operation returns a result or retained state that violates this contract: Extend by the iterable elements, without recursively flattening nested elements.
List extend expands one level · case 05
The operation returns a result or retained state that violates this contract: Extend by the iterable elements, without recursively flattening nested elements.
List clear preserves alias reference · case 01
The operation returns a result or retained state that violates this contract: Clear the list in place so an existing alias observes an empty list; return [target,alias].
List clear preserves alias reference · case 02
The operation returns a result or retained state that violates this contract: Clear the list in place so an existing alias observes an empty list; return [target,alias].
List clear preserves alias reference · case 03
The operation returns a result or retained state that violates this contract: Clear the list in place so an existing alias observes an empty list; return [target,alias].
List clear preserves alias reference · case 04
The operation returns a result or retained state that violates this contract: Clear the list in place so an existing alias observes an empty list; return [target,alias].
List clear preserves alias reference · case 05
The operation returns a result or retained state that violates this contract: Clear the list in place so an existing alias observes an empty list; return [target,alias].
Map get preserves falsy value · case 01
The operation returns a result or retained state that violates this contract: Look up a key and use the fallback only when absent; falsy present values are retained.
Map get preserves falsy value · case 02
The operation returns a result or retained state that violates this contract: Look up a key and use the fallback only when absent; falsy present values are retained.
Map get preserves falsy value · case 03
The operation returns a result or retained state that violates this contract: Look up a key and use the fallback only when absent; falsy present values are retained.
Map get preserves falsy value · case 04
The operation returns a result or retained state that violates this contract: Look up a key and use the fallback only when absent; falsy present values are retained.
Map get preserves falsy value · case 05
The operation returns a result or retained state that violates this contract: Look up a key and use the fallback only when absent; falsy present values are retained.
Map setdefault keeps existing none · case 01
The operation returns a result or retained state that violates this contract: Insert the default only for an absent key; return [selected value,map].
Map setdefault keeps existing none · case 02
The operation returns a result or retained state that violates this contract: Insert the default only for an absent key; return [selected value,map].
Map setdefault keeps existing none · case 03
The operation returns a result or retained state that violates this contract: Insert the default only for an absent key; return [selected value,map].
Map setdefault keeps existing none · case 04
The operation returns a result or retained state that violates this contract: Insert the default only for an absent key; return [selected value,map].
Map setdefault keeps existing none · case 05
The operation returns a result or retained state that violates this contract: Insert the default only for an absent key; return [selected value,map].
Map pop preserves present default value · case 01
The operation returns a result or retained state that violates this contract: Pop a key if present and return [value,remaining map], using fallback only when absent.
Map pop preserves present default value · case 02
The operation returns a result or retained state that violates this contract: Pop a key if present and return [value,remaining map], using fallback only when absent.
Map pop preserves present default value · case 03
The operation returns a result or retained state that violates this contract: Pop a key if present and return [value,remaining map], using fallback only when absent.
Map pop preserves present default value · case 04
The operation returns a result or retained state that violates this contract: Pop a key if present and return [value,remaining map], using fallback only when absent.
Map pop preserves present default value · case 05
The operation returns a result or retained state that violates this contract: Pop a key if present and return [value,remaining map], using fallback only when absent.
Map update right precedence · case 01
The operation returns a result or retained state that violates this contract: Update existing keys from the right map while retaining left insertion positions and appending new right keys.
Map update right precedence · case 02
The operation returns a result or retained state that violates this contract: Update existing keys from the right map while retaining left insertion positions and appending new right keys.
Map update right precedence · case 03
The operation returns a result or retained state that violates this contract: Update existing keys from the right map while retaining left insertion positions and appending new right keys.
Map update right precedence · case 04
The operation returns a result or retained state that violates this contract: Update existing keys from the right map while retaining left insertion positions and appending new right keys.
Map update right precedence · case 05
The operation returns a result or retained state that violates this contract: Update existing keys from the right map while retaining left insertion positions and appending new right keys.
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 ↗