fix: pass correct log-source for stderr

There was a mistake in `WaitFor::message_on_stderr`. Covered with simple test now.

testcontainers/src/core/logs.rs

@@ -135,7 +135,7 @@ impl fmt::Debug for WaitingStreamWrapper {
 mod tests {
     use super::*;
 
-    #[tokio::test(flavor = "multi_thread")]
+    #[tokio::test]
     async fn given_logs_when_line_contains_message_should_find_it() {
         let _ = pretty_env_logger::try_init();
         let log_stream = || {

testcontainers/src/core/wait/mod.rs

@@ -49,7 +49,7 @@ impl WaitFor {
 
     /// Wait for the message to appear on the container's stderr.
     pub fn message_on_stderr(message: impl AsRef<[u8]>) -> WaitFor {
-        Self::log(LogWaitStrategy::new(LogSource::StdOut, message))
+        Self::log(LogWaitStrategy::new(LogSource::StdErr, message))
     }
 
     /// Wait for the message to appear on the container's stdout.

testcontainers/tests/async_runner.rs

@@ -101,6 +101,7 @@ async fn async_run_exec() -> anyhow::Result<()> {
     let _ = pretty_env_logger::try_init();
 
     let image = GenericImage::new("simple_web_server", "latest")
+        .with_wait_for(WaitFor::message_on_stderr("server will be listening to"))
         .with_wait_for(WaitFor::log(
             LogWaitStrategy::stdout("server is ready").with_times(2),
         ))

testimages/src/bin/simple_web_server.rs

@@ -12,6 +12,7 @@ async fn main() {
     // run it
     let addr = SocketAddr::from(([0, 0, 0, 0], 80));
     let listener = tokio::net::TcpListener::bind(addr).await.unwrap();
+    eprintln!("server will be listening to the port 80");
     println!("server is ready");
     println!("server is ready"); // duplicate line to test `times` parameter of `WaitFor::Log`
     axum::serve(listener, app.into_make_service())