vendor/env_logger-0.5.13/tests/regexp_filter.rs

#[macro_use] extern crate log;
extern crate env_logger;

use std::process;
use std::env;
use std::str;

fn main() {
    if env::var("LOG_REGEXP_TEST").ok() == Some(String::from("1")) {
        child_main();
    } else {
        parent_main()
    }
}

fn child_main() {
    env_logger::init();
    info!("XYZ Message");
}

fn run_child(rust_log: String) -> bool {
    let exe = env::current_exe().unwrap();
    let out = process::Command::new(exe)
        .env("LOG_REGEXP_TEST", "1")
        .env("RUST_LOG", rust_log)
        .output()
        .unwrap_or_else(|e| panic!("Unable to start child process: {}", e));
    str::from_utf8(out.stderr.as_ref()).unwrap().contains("XYZ Message")
}

fn assert_message_printed(rust_log: &str) {
    if !run_child(rust_log.to_string()) {
        panic!("RUST_LOG={} should allow the test log message", rust_log)
    }
}

fn assert_message_not_printed(rust_log: &str) {
    if run_child(rust_log.to_string()) {
        panic!("RUST_LOG={} should not allow the test log message", rust_log)
    }
}

fn parent_main() {
    // test normal log severity levels
    assert_message_printed("info");
    assert_message_not_printed("warn");

    // test of regular expression filters
    assert_message_printed("info/XYZ");
    assert_message_not_printed("info/XXX");
}