Cargo Features

secp256k1-test has no features set by default.

[dependencies]
secp256k1-test = { version = "0.7.2", features = ["unstable", "dev"] }
unstable
dev = clippy

Features from optional dependencies

In crates that don't use the dep: syntax, optional dependencies automatically become Cargo features. These features may have been created by mistake, and this functionality may be removed in the future.

clippy dev?