It's used only as a dev dependency in 6 crates.

Depender (with downloads and own rev deps) RegexTest version
19.5M 65 regex-automata dev ^0.1.0
14.3M 10431 regex dev ^0.1.0
2.2M 449 regex-lite dev ^0.1.0
3.7K 1 regex-cursor dev ^0.1.0
110 2 kbnf-regex-automata dev ^0.1.0
100 supply-chain-trust-example-crate-000021 dev ^0.1.0