tests: rework the actually useful tests to live in the integration crate

crates/irtt-app/tests/support/in_tree_server.rs

@@ -0,0 +1,74 @@
+use std::{
+    net::{IpAddr, Ipv4Addr, SocketAddr},
+    sync::mpsc,
+    thread::{self, JoinHandle},
+    time::Duration,
+};
+
+use irtt_server::{Server, ServerConfig};
+use tokio::sync::oneshot;
+
+const STARTUP_TIMEOUT: Duration = Duration::from_secs(2);
+
+pub struct InTreeServer {
+    pub addr: SocketAddr,
+    shutdown: Option<oneshot::Sender<()>>,
+    done: Option<JoinHandle<Result<(), irtt_server::ServerRuntimeError>>>,
+}
+
+impl InTreeServer {
+    pub fn start(config: ServerConfig) -> Self {
+        let (startup_tx, startup_rx) = mpsc::sync_channel(1);
+        let (shutdown_tx, shutdown_rx) = oneshot::channel();
+        let done = thread::spawn(move || {
+            let runtime = tokio::runtime::Builder::new_current_thread()
+                .enable_all()
+                .build()
+                .expect("failed to build in-tree test server runtime");
+            runtime.block_on(async move {
+                let bind_addr = SocketAddr::new(IpAddr::V4(Ipv4Addr::LOCALHOST), 0);
+                let mut server = Server::bind(bind_addr, config).await?;
+                startup_tx
+                    .send(server.local_addr()?)
+                    .expect("test stopped waiting for in-tree server startup");
+                server
+                    .run(async {
+                        let _ = shutdown_rx.await;
+                    })
+                    .await
+            })
+        });
+
+        let addr = match startup_rx.recv_timeout(STARTUP_TIMEOUT) {
+            Ok(addr) => addr,
+            Err(error) => {
+                let _ = shutdown_tx.send(());
+                let result = done.join().expect("in-tree test server thread panicked");
+                panic!("in-tree test server failed before startup ({error}): {result:?}");
+            }
+        };
+
+        Self {
+            addr,
+            shutdown: Some(shutdown_tx),
+            done: Some(done),
+        }
+    }
+
+    fn stop_inner(&mut self) {
+        if let Some(shutdown) = self.shutdown.take() {
+            let _ = shutdown.send(());
+        }
+        if let Some(done) = self.done.take() {
+            done.join()
+                .expect("in-tree test server thread panicked")
+                .expect("in-tree test server stopped with an error");
+        }
+    }
+}
+
+impl Drop for InTreeServer {
+    fn drop(&mut self) {
+        self.stop_inner();
+    }
+}