tests: hide log messages from output in successful tests — radicle-ci-broker

This was unexpectedly difficult to figure out, but I got there.

Signed-off-by: Lars Wirzenius liw@liw.fi

 use std::sync::Once;
 use std::{
     fmt,
     io::Write,
     path::Path,
     sync::{Arc, Mutex},
     time::Duration,

     }
 }
 // A custom type for log output. We need this to hide log messages
 // from output in successful tests. Cargo will hide standard output
 // and error by default, which is what we want, but it seems this only
 // applies to output via the `print!` family of macros. If we open a
 // new handle for stdout or stderr, output via that handle is not
 // captured by Cargo.
 //
 // Instead, we have our own log writer type that writes to stderr in
 // production mode, and uses `print!` in tests.
 #[derive(Default)]
 struct LogWriter {}
 #[cfg(test)]
 impl Write for LogWriter {
     fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
         let s = String::from_utf8_lossy(buf);
         print!("{s}");
         Ok(buf.len())
     }
     fn flush(&mut self) -> std::io::Result<()> {
         Ok(())
     }
 }
 #[cfg(not(test))]
 impl Write for LogWriter {
     fn write(&mut self, buf: &[u8]) -> std::io::Result<usize> {
         let mut stderr = std::io::stderr();
         stderr.write_all(buf)?;
         stderr.flush()?;
         Ok(buf.len())
     }
     fn flush(&mut self) -> std::io::Result<()> {
         Ok(())
     }
 }
 pub struct Logger {
     minimum_log_level: Arc<Mutex<slog::Level>>,

 }
 pub fn open() -> Logger {
     let underlying_logger = slog_json::Json::new(std::io::stderr())
     let underlying_logger = slog_json::Json::new(LogWriter::default())
         .add_default_keys()
         .set_flush(true)
         .set_newlines(true)