feat: adding test to make sure we can gracefully shutdown

Signed-off-by: kjuulh <contact@kjuulh.io>

crates/mad/tests/mod.rs

@@ -1,6 +1,9 @@
+use std::sync::Arc;
+
 use async_trait::async_trait;
 use notmad::{Component, Mad};
 use rand::Rng;
+use tokio::sync::Mutex;
 use tokio_util::sync::CancellationToken;
 use tracing_test::traced_test;
 
@@ -86,3 +89,51 @@ async fn test_can_run_components() -> anyhow::Result<()> {
 
     Ok(())
 }
+
+#[tokio::test]
+#[traced_test]
+async fn test_can_shutdown_gracefully() -> anyhow::Result<()> {
+    let check = Arc::new(Mutex::new(None));
+
+    Mad::builder()
+        .add_fn({
+            let check = check.clone();
+
+            move |cancel| {
+                let check = check.clone();
+
+                async move {
+                    let start = std::time::SystemTime::now();
+                    tracing::info!("waiting for cancel");
+                    cancel.cancelled().await;
+                    tracing::info!("submitting check");
+                    let mut check = check.lock().await;
+                    let elapsed = start.elapsed().expect("to be able to get elapsed");
+                    *check = Some(elapsed);
+                    tracing::info!("check submitted");
+
+                    Ok(())
+                }
+            }
+        })
+        .add_fn(|_| async move {
+            tracing::info!("starting sleep");
+            tokio::time::sleep(std::time::Duration::from_millis(100)).await;
+            tracing::info!("sleep ended");
+
+            Ok(())
+        })
+        .run()
+        .await?;
+
+    let check = check
+        .lock()
+        .await
+        .expect("to be able to get a duration from cancel");
+
+    // We default wait 100 ms for graceful shutdown, and we explicitly wait 100ms in the sleep routine
+    tracing::info!("check millis: {}", check.as_millis());
+    assert!(check.as_millis() < 250);
+
+    Ok(())
+}