There's a lot of tests: https://github.com/rust-lang/rust/blob/f66fd2eed10de2acacd8af73c704bf4d140410bb/src/libcollections/str.rs#L870-L2356 https://github.com/

There's a lot of tests: https://github.com/rust-lang/rust/blob/f66fd2eed10de2acacd8af73c704bf4d140410bb/src/libcollections/str.rs#L870-L2356 https://github.com/rust-lang/rust/blob/f66fd2eed10de2acacd8a... Testing is something Rust is very big on, e.g. we run the test suite on many architectures/platforms each pull request and merge only if it passes on all: master is always green.