refactor(workspace): enforce layered crate boundaries

crates/aether-testing/testkit/src/server.rs

@@ -0,0 +1,64 @@
+use std::fmt;
+use std::net::SocketAddr;
+
+use axum::Router;
+
+pub struct SpawnedServer {
+    base_url: String,
+    port: u16,
+    handle: tokio::task::JoinHandle<()>,
+}
+
+impl SpawnedServer {
+    pub async fn start(app: Router) -> Result<Self, std::io::Error> {
+        let port = reserve_local_port()?;
+        Self::start_on_port(port, app).await
+    }
+
+    pub async fn start_on_port(port: u16, app: Router) -> Result<Self, std::io::Error> {
+        let listener = tokio::net::TcpListener::bind(("127.0.0.1", port)).await?;
+        let addr = listener.local_addr()?;
+        let handle = tokio::spawn(async move {
+            axum::serve(
+                listener,
+                app.into_make_service_with_connect_info::<SocketAddr>(),
+            )
+            .await
+            .expect("spawned server should run");
+        });
+        Ok(Self {
+            base_url: format!("http://{addr}"),
+            port: addr.port(),
+            handle,
+        })
+    }
+
+    pub fn base_url(&self) -> &str {
+        &self.base_url
+    }
+
+    pub fn port(&self) -> u16 {
+        self.port
+    }
+}
+
+impl fmt::Debug for SpawnedServer {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("SpawnedServer")
+            .field("base_url", &self.base_url)
+            .finish_non_exhaustive()
+    }
+}
+
+impl Drop for SpawnedServer {
+    fn drop(&mut self) {
+        self.handle.abort();
+    }
+}
+
+pub fn reserve_local_port() -> Result<u16, std::io::Error> {
+    let listener = std::net::TcpListener::bind("127.0.0.1:0")?;
+    let port = listener.local_addr()?.port();
+    drop(listener);
+    Ok(port)
+}