The project has an interesting concept they call Unity where they have setup external projects using CUE as part of their regression test suite, meaning they’ll get early feedback from those tests when making releases if they have broken something that users rely on.

black

has something similar where PRs are ran against common codebases to see what kind of diff (if any) the new code would produce

ansible-lint

has some similar “eco” tests to test the ecosystem… But it’s really annoying, because adding new features (new lint checks) means that those eco repos will fail until they are updated to use the last lint rules. So, if we have something like this, don’t make it hard to update, or annoying to develop things with it. 🙂

If we’re listing similar tools, Rust has crater (https://rustc-dev-guide.rust-lang.org/tests/crater.html) to run a new compiler/stdlib against all crates published on crates.io. This is opt-in for individual PRs and also run before releases, I think

Oh, this is great--please list more projects using this concept, I wasn’t aware it was so widespread 🙂