Add idle test

edb/server/conn_pool/src/pool.rs

@@ -232,6 +232,10 @@ impl<C: Connector> Pool<C> {
         self.blocks.summary()
     }
 
+    pub fn idle(&self) -> bool {
+        self.blocks.is_empty()
+    }
+
     pub async fn shutdown(self: Rc<Self>) {
         _ = tokio::task::spawn_local(async {
             let mut pool = self;
@@ -278,6 +282,27 @@ mod tests {
             .await
     }
 
+    #[test(tokio::test(flavor = "current_thread", start_paused = true))]
+    async fn test_pool_eventually_idles() -> Result<()> {
+        let future = async {
+            let config = PoolConfig::suggested_default_for(10);
+
+            let pool = Pool::new(config, BasicConnector::no_delay());
+            let conn = pool.acquire("1").await?;
+            tokio::time::sleep(Duration::from_millis(10)).await;
+            drop(conn);
+
+            while !pool.idle() {
+                tokio::time::sleep(Duration::from_millis(10)).await;
+                pool.run_once();
+            }
+
+            pool.shutdown().await;
+            Ok(())
+        };
+        tokio::time::timeout(Duration::from_secs(60), LocalSet::new().run_until(future)).await?
+    }
+
     #[test(tokio::test(flavor = "current_thread", start_paused = true))]
     #[rstest]
     #[case::one(1)]