[josephg]

I regularly write custom, small, “fuzzers” in my test suites - at least when I can. For example, recently I’ve implemented a btree for a project with some custom optimisations. My test suite includes a fuzzer which randomly mutates the btree and performs the same mutations on a slower reference data structure. After each change, I test that both structures contain the same data.

The test has shaken out about 10 obscure bugs in my code that my other unit tests failed to find. And that is about what I expected - it’s what I find more or less every time I do randomised testing on code that hasn’t experienced this before.

I really think this sort of testing should be taught and done almost everywhere. It’s wild how many bugs you find with randomly generated input. It is by far the most efficient unit testing you can do, measured by bugs found per line of testing code.

[fanf2]

Definitely, yes!

John Regehr has a nice tutorial, https://blog.regehr.org/archives/896