We love tests. Oh my, do we love tests. I love tests. We’ve got more tests.

I’ve added two more auto builders to our CI. The ‘auto’ builders are those that bors runs before merging and prevent Rust from breaking, and each represents a distinct configuration for Rust. Today we test Rust in 36 configurations every pull request, 31 of which are required to pass before the PR can land.

If you haven’t seen the wall of builders it is staggering.

These two new builders are called auto-linux-64-cargotest and auto-win-msvc-64-cargotest and they do something new.

They run a tool in the new build system called ‘cargotest’, which does one simple thing: downloads revisions of a few key crates, builds them and tests them. The crates it builds are chosen because they are prominent projects with broad dependencies. Today they are just two: Cargo and Iron. Between them are 76 transitive dependencies, the most battle-tested crates in the ecosystem, one of which is winapi.

bors gates on the cargotest builders, so it will be very hard to break any of these crates without some deep soul searching.

Tests!