Interface EnvLookup

atomic-cli/src/commands/update.rs:128–130

Environment lookup, injected so tests don't have to mutate the real process environment.

/// Environment lookup, injected so tests don't have to mutate the real
/// process environment.
pub trait EnvLookup {
    fn var(&self, key: &str) -> Option<String>;
}

/// Production implementation backed by `std::env`.
pub struct StdEnv;