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
Slippy map tile index from coordinates: column clamp · case 01
Points exactly on the antimeridian at +180 are placed in column 0 or beyond the grid.
Slippy map tile index from coordinates: column clamp · case 02
Points exactly on the antimeridian at +180 are placed in column 0 or beyond the grid.
Slippy map tile index from coordinates: column clamp · case 03
Points exactly on the antimeridian at +180 are placed in column 0 or beyond the grid.
Slippy map tile index from coordinates: column clamp · case 04
Points exactly on the antimeridian at +180 are placed in column 0 or beyond the grid.
Slippy map tile index from coordinates: column clamp · case 05
Points exactly on the antimeridian at +180 are placed in column 0 or beyond the grid.
Slippy map tile index from coordinates: row lower clamp · case 01
Latitudes beyond the mercator limit produce negative row numbers.
Slippy map tile index from coordinates: row lower clamp · case 02
Latitudes beyond the mercator limit produce negative row numbers.
Slippy map tile index from coordinates: row lower clamp · case 03
Latitudes beyond the mercator limit produce negative row numbers.
Slippy map tile index from coordinates: row lower clamp · case 04
Latitudes beyond the mercator limit produce negative row numbers.
Slippy map tile index from coordinates: row lower clamp · case 05
Latitudes beyond the mercator limit produce negative row numbers.
Slippy map tile index from coordinates: column rounding · case 01
Points in the eastern half of a tile are assigned to the next column.
Slippy map tile index from coordinates: column rounding · case 02
Points in the eastern half of a tile are assigned to the next column.
Slippy map tile index from coordinates: column rounding · case 03
Points in the eastern half of a tile are assigned to the next column.
Slippy map tile index from coordinates: column rounding · case 04
Points in the eastern half of a tile are assigned to the next column.
Slippy map tile index from coordinates: column rounding · case 05
Points in the eastern half of a tile are assigned to the next column.
Geographic bounds of a map tile: tms row flip · case 01
TMS tiles report bounds one tile further south than their neighbours report.
Geographic bounds of a map tile: tms row flip · case 02
TMS tiles report bounds one tile further south than their neighbours report.
Geographic bounds of a map tile: tms row flip · case 03
TMS tiles report bounds one tile further south than their neighbours report.
Geographic bounds of a map tile: tms row flip · case 04
TMS tiles report bounds one tile further south than their neighbours report.
Geographic bounds of a map tile: tms row flip · case 05
TMS tiles report bounds one tile further south than their neighbours report.
Geographic bounds of a map tile: north edge row · case 01
Tiles have zero height: north equals south.
Geographic bounds of a map tile: north edge row · case 02
Tiles have zero height: north equals south.
Geographic bounds of a map tile: north edge row · case 03
Tiles have zero height: north equals south.
Geographic bounds of a map tile: north edge row · case 04
Tiles have zero height: north equals south.
Geographic bounds of a map tile: north edge row · case 05
Tiles have zero height: north equals south.
Geographic bounds of a map tile: edge latitude factor · case 01
All tile edges crowd toward the north, the south half of the world disappears.
Geographic bounds of a map tile: edge latitude factor · case 02
All tile edges crowd toward the north, the south half of the world disappears.
Geographic bounds of a map tile: edge latitude factor · case 03
All tile edges crowd toward the north, the south half of the world disappears.
Geographic bounds of a map tile: edge latitude factor · case 04
All tile edges crowd toward the north, the south half of the world disappears.
Geographic bounds of a map tile: edge latitude factor · case 05
All tile edges crowd toward the north, the south half of the world disappears.
Geographic bounds of a map tile: east edge column · case 01
Tiles have zero width: west equals east.
Geographic bounds of a map tile: east edge column · case 02
Tiles have zero width: west equals east.
Geographic bounds of a map tile: east edge column · case 03
Tiles have zero width: west equals east.
Geographic bounds of a map tile: east edge column · case 04
Tiles have zero width: west equals east.
Geographic bounds of a map tile: east edge column · case 05
Tiles have zero width: west equals east.
Geographic bounds of a map tile: longitude span · case 01
Western tile edges drift east of the matching eastern edge of the neighbour tile.
Geographic bounds of a map tile: longitude span · case 02
Western tile edges drift east of the matching eastern edge of the neighbour tile.
Geographic bounds of a map tile: longitude span · case 03
Western tile edges drift east of the matching eastern edge of the neighbour tile.
Geographic bounds of a map tile: longitude span · case 04
Western tile edges drift east of the matching eastern edge of the neighbour tile.
Geographic bounds of a map tile: longitude span · case 05
Western tile edges drift east of the matching eastern edge of the neighbour tile.
Bing-style quadkey encoding of a tile: digit significance order · case 01
Quadkeys of neighbouring tiles no longer share their parent prefix.
Bing-style quadkey encoding of a tile: digit significance order · case 02
Quadkeys of neighbouring tiles no longer share their parent prefix.
Bing-style quadkey encoding of a tile: digit significance order · case 03
Quadkeys of neighbouring tiles no longer share their parent prefix.
Bing-style quadkey encoding of a tile: digit significance order · case 04
Quadkeys of neighbouring tiles no longer share their parent prefix.
Bing-style quadkey encoding of a tile: digit significance order · case 05
Quadkeys of neighbouring tiles no longer share their parent prefix.
Bing-style quadkey encoding of a tile: bit mask position · case 01
Keys read the wrong bit and tiles in odd columns get even-column keys.
Bing-style quadkey encoding of a tile: bit mask position · case 02
Keys read the wrong bit and tiles in odd columns get even-column keys.
Bing-style quadkey encoding of a tile: bit mask position · case 03
Keys read the wrong bit and tiles in odd columns get even-column keys.
Bing-style quadkey encoding of a tile: bit mask position · case 04
Keys read the wrong bit and tiles in odd columns get even-column keys.
Bing-style quadkey encoding of a tile: bit mask position · case 05
Keys read the wrong bit and tiles in odd columns get even-column keys.
Bing-style quadkey encoding of a tile: column digit weight · case 01
East and south quadrants are confused in generated keys.
Bing-style quadkey encoding of a tile: column digit weight · case 02
East and south quadrants are confused in generated keys.
Bing-style quadkey encoding of a tile: column digit weight · case 03
East and south quadrants are confused in generated keys.
Bing-style quadkey encoding of a tile: column digit weight · case 04
East and south quadrants are confused in generated keys.
Bing-style quadkey encoding of a tile: column digit weight · case 05
East and south quadrants are confused in generated keys.
Bing-style quadkey encoding of a tile: zoom zero key · case 01
The world tile at zoom 0 gets a one-character key that collides with a zoom-1 tile.
Bing-style quadkey encoding of a tile: zoom zero key · case 02
The world tile at zoom 0 gets a one-character key that collides with a zoom-1 tile.
Bing-style quadkey encoding of a tile: zoom zero key · case 03
The world tile at zoom 0 gets a one-character key that collides with a zoom-1 tile.
Bing-style quadkey encoding of a tile: zoom zero key · case 04
The world tile at zoom 0 gets a one-character key that collides with a zoom-1 tile.
Bing-style quadkey encoding of a tile: zoom zero key · case 05
The world tile at zoom 0 gets a one-character key that collides with a zoom-1 tile.
Bing-style quadkey encoding of a tile: range upper bound · case 01
Tiles one past the grid edge get keys instead of being rejected.
Bing-style quadkey encoding of a tile: range upper bound · case 02
Tiles one past the grid edge get keys instead of being rejected.
Bing-style quadkey encoding of a tile: range upper bound · case 03
Tiles one past the grid edge get keys instead of being rejected.
Bing-style quadkey encoding of a tile: range upper bound · case 04
Tiles one past the grid edge get keys instead of being rejected.
Bing-style quadkey encoding of a tile: range upper bound · case 05
Tiles one past the grid edge get keys instead of being rejected.
Web mercator ground resolution and scale denominator: latitude cosine unit · case 01
Resolution oscillates and even turns negative across latitudes.
Web mercator ground resolution and scale denominator: latitude cosine unit · case 02
Resolution oscillates and even turns negative across latitudes.
Web mercator ground resolution and scale denominator: latitude cosine unit · case 03
Resolution oscillates and even turns negative across latitudes.
Web mercator ground resolution and scale denominator: latitude cosine unit · case 04
Resolution oscillates and even turns negative across latitudes.
Web mercator ground resolution and scale denominator: latitude cosine unit · case 05
Resolution oscillates and even turns negative across latitudes.
Web mercator ground resolution and scale denominator: tile size scaling · case 01
512-pixel tile pyramids report four times the true metres per pixel.
Web mercator ground resolution and scale denominator: tile size scaling · case 02
512-pixel tile pyramids report four times the true metres per pixel.
Web mercator ground resolution and scale denominator: tile size scaling · case 03
512-pixel tile pyramids report four times the true metres per pixel.
Web mercator ground resolution and scale denominator: tile size scaling · case 04
512-pixel tile pyramids report four times the true metres per pixel.
Web mercator ground resolution and scale denominator: tile size scaling · case 05
512-pixel tile pyramids report four times the true metres per pixel.
Web mercator ground resolution and scale denominator: zoom exponent · case 01
Every zoom level reports half the correct resolution.
Web mercator ground resolution and scale denominator: zoom exponent · case 02
Every zoom level reports half the correct resolution.
Web mercator ground resolution and scale denominator: zoom exponent · case 03
Every zoom level reports half the correct resolution.
Web mercator ground resolution and scale denominator: zoom exponent · case 04
Every zoom level reports half the correct resolution.
Web mercator ground resolution and scale denominator: zoom exponent · case 05
Every zoom level reports half the correct resolution.
Web mercator ground resolution and scale denominator: inch conversion · case 01
Scale denominators are ten times too small.
Web mercator ground resolution and scale denominator: inch conversion · case 02
Scale denominators are ten times too small.
Web mercator ground resolution and scale denominator: inch conversion · case 03
Scale denominators are ten times too small.
Web mercator ground resolution and scale denominator: inch conversion · case 04
Scale denominators are ten times too small.
Web mercator ground resolution and scale denominator: inch conversion · case 05
Scale denominators are ten times too small.
Web mercator ground resolution and scale denominator: rounding stage · case 01
Scale denominators at high zoom levels are off by several hundred.
Web mercator ground resolution and scale denominator: rounding stage · case 02
Scale denominators at high zoom levels are off by several hundred.
Web mercator ground resolution and scale denominator: rounding stage · case 03
Scale denominators at high zoom levels are off by several hundred.
Web mercator ground resolution and scale denominator: rounding stage · case 04
Scale denominators at high zoom levels are off by several hundred.
Web mercator ground resolution and scale denominator: rounding stage · case 05
Scale denominators at high zoom levels are off by several hundred.
UTM zone and latitude band lookup: antimeridian zone cap · case 01
Points exactly on +180 get a non-existent zone 61.
UTM zone and latitude band lookup: antimeridian zone cap · case 02
Points exactly on +180 get a non-existent zone 61.
UTM zone and latitude band lookup: antimeridian zone cap · case 03
Points exactly on +180 get a non-existent zone 61.
UTM zone and latitude band lookup: antimeridian zone cap · case 04
Points exactly on +180 get a non-existent zone 61.
UTM zone and latitude band lookup: antimeridian zone cap · case 05
Points exactly on +180 get a non-existent zone 61.
UTM zone and latitude band lookup: norway exception west edge · case 01
Points on the 3 degree meridian in southern Norway stay in zone 31.
UTM zone and latitude band lookup: norway exception west edge · case 02
Points on the 3 degree meridian in southern Norway stay in zone 31.
UTM zone and latitude band lookup: norway exception west edge · case 03
Points on the 3 degree meridian in southern Norway stay in zone 31.
UTM zone and latitude band lookup: norway exception west edge · case 04
Points on the 3 degree meridian in southern Norway stay in zone 31.
UTM zone and latitude band lookup: norway exception west edge · case 05
Points on the 3 degree meridian in southern Norway stay in zone 31.
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 ↗