We use <a href="https://docs.rs/proptest/latest/proptest/" rel="nofollow">https://docs.rs/proptest/latest/proptest/</a> extensively at Remind. It very recently got a few new maintainers and does shrinking pretty well.<p>Our biggest use case has been testing our database materialization. We have a somewhat complicated hierarchical organization tree/forest within our database. In order to efficiently query those structures, we materialize the transitive closure of these relationships. TL;DR; we populate a row for each (org, ancestor) and maintain that via postgres triggers that fire whenever we mutate things.<p>The prop test that tests it all does three things. First, it establishes an arbitrary that captures all the possible shapes of organization trees. Second, we define the set of mutations (add a child, switch parents, delete a grandparent, etc.) that may occur. Third, we have code for reading/writing org trees to and from the DB.<p>The test then generates an org tree, syncs it to the db, performs 1 or more mutations on the tree and then compares what's in the database with the resulting tree.<p>Overall it's been pretty great. I highly recommend property tests, especially when modeling complex data in an external system.