lib.rs also needs a cfg(test) on the module declaration

Looks like that already exists in lib.rs actually: https://github.com/unicode-rs/unicode-normalization/blob/master/src/lib.rs#L70

Maybe that makes setting it on the constant redundant and the Cargo.toml change is the only one here that does anything?

Yep, I think the issue in #28 is that the test files are included in the crate, not that they're getting compiled. The extant cfg(test) in lib.rs ensures they're not compiled. Revert to just the Cargo.toml change?

Rebased to drop the cfg commit