SimpleLog with cargo test - usage

help
1

I have some code with logging, and when running cargo test, I'd like to have the log messages hidden unless I do cargo test -- --nocapture. So I'd like to have a logger which does "println!" to standard output and nothing more or less - no buffering, no sending some stuff to stderr, etc. The default logger somehow escapes whatever mechanism cargo test uses to capture and hide output, so I get unwanted output for successful logs. How can I suppress that?

2 
struct TestLogger;
impl std::io::Write for TestLogger {
    fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
        print!("{}", std::str::from_utf8(buf).unwrap());
        Ok(buf.len())
    }

    fn flush(&mut self) -> std::io::Result<()> {
        Ok(())
    }
}

#[test]
fn test() {
    simplelog::WriteLogger::init(log::LevelFilter::Error, Default::default(), TestLogger)
        .expect("log initialization failed");
    log::error!("error");
}

$ cargo t -- --nocapture
running 1 test
test test ... 08:13:19 [ERROR] error
ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

$ cargo t
running 1 test
test test ... ok

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

or simply test-log — Rust testing library // Lib.rs which uses env_logger or tracing though.

3

test_log suggests

let _ = env_logger::builder().is_test(true).try_init();

which seems promising. Have to try that. I'm looking for a one-liner I can put in unit tests.