manual_clamp: add more tests, address style nit

Author: Xaeroxe

Cargo.toml

@@ -45,7 +45,6 @@ rustc-workspace-hack = "1.0"
 clap = { version = "3.1", features = ["derive"] }
 clippy_utils = { path = "clippy_utils" }
 derive-new = "0.5"
-rand = "0.8"
 if_chain = "1.0"
 itertools = "0.10.1"
 quote = "1.0"