Function compose_child_env 

pub fn compose_child_env(pairs: &[(&str, &str)]) -> Vec<(String, String)>

Compose user-provided (key, value) pairs into the SIMCTL_CHILD_* envp that xcrun simctl launch strips and delivers to the launched app. Idempotent: a key that already starts with SIMCTL_CHILD_ is passed through unchanged.

Example

use smix_simctl::compose_child_env;
let composed = compose_child_env(&[("SMIX_PERF_RECEIVER_URL", "http://h:9999")]);
assert_eq!(
    composed,
    vec![(
        "SIMCTL_CHILD_SMIX_PERF_RECEIVER_URL".to_string(),
        "http://h:9999".to_string(),
    )]
);