I've noticed that the hash_map and hash_set strategies can be quite severe footguns. Iteration order of HashMaps and HashSets is non-deterministic. Hence, composing more strategies on top of a hash_map with .prop_flat_map will most likely yield non-deterministic behaviour and completely break the idea of reproducing a failing test case based on its seed.
I've spent many hours debugging my tests (proptest-state-machine specifically) until I finally got to the bottom of this.
I am not sure if deprecation is the right call but I think it should be called out or warned about somewhere.
I've noticed that the
hash_mapandhash_setstrategies can be quite severe footguns. Iteration order ofHashMaps andHashSets is non-deterministic. Hence, composing more strategies on top of ahash_mapwith.prop_flat_mapwill most likely yield non-deterministic behaviour and completely break the idea of reproducing a failing test case based on its seed.I've spent many hours debugging my tests (
proptest-state-machinespecifically) until I finally got to the bottom of this.I am not sure if deprecation is the right call but I think it should be called out or warned about somewhere.