diff --git a/actix-http/src/client/connection.rs b/actix-http/src/client/connection.rs
index c513310b9..0b2c6e1df 100644
--- a/actix-http/src/client/connection.rs
+++ b/actix-http/src/client/connection.rs
@@ -141,6 +141,11 @@ impl<T: AsyncRead + AsyncWrite + Unpin> IoConnection<T> {
     pub(crate) fn into_inner(self) -> (ConnectionType<T>, time::Instant) {
         (self.io.unwrap(), self.created)
     }
+
+    #[cfg(test)]
+    pub(crate) fn into_parts(self) -> (ConnectionType<T>, time::Instant, Acquired<T>) {
+        (self.io.unwrap(), self.created, self.pool.unwrap())
+    }
 }
 
 impl<T> Connection for IoConnection<T>
diff --git a/actix-http/src/client/pool.rs b/actix-http/src/client/pool.rs
index 01a7535e3..5e1451c6c 100644
--- a/actix-http/src/client/pool.rs
+++ b/actix-http/src/client/pool.rs
@@ -377,3 +377,187 @@ where
         let _permit = &mut self.permit;
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    use std::cell::Cell;
+    use std::io;
+
+    use http::Uri;
+
+    use crate::client::connection::IoConnection;
+
+    // A stream type always return pending on async read.
+    // mock a usable tcp stream that ready to be used as client
+    struct TestStream;
+
+    impl AsyncRead for TestStream {
+        fn poll_read(
+            self: Pin<&mut Self>,
+            _: &mut Context<'_>,
+            _: &mut ReadBuf<'_>,
+        ) -> Poll<io::Result<()>> {
+            Poll::Pending
+        }
+    }
+
+    impl AsyncWrite for TestStream {
+        fn poll_write(
+            self: Pin<&mut Self>,
+            _: &mut Context<'_>,
+            _: &[u8],
+        ) -> Poll<io::Result<usize>> {
+            unimplemented!()
+        }
+
+        fn poll_flush(
+            self: Pin<&mut Self>,
+            _: &mut Context<'_>,
+        ) -> Poll<io::Result<()>> {
+            unimplemented!()
+        }
+
+        fn poll_shutdown(
+            self: Pin<&mut Self>,
+            _: &mut Context<'_>,
+        ) -> Poll<io::Result<()>> {
+            unimplemented!()
+        }
+    }
+
+    struct TestPoolConnector {
+        generated: Rc<Cell<usize>>,
+    }
+
+    impl Service<Connect> for TestPoolConnector {
+        type Response = (TestStream, Protocol);
+        type Error = ConnectError;
+        type Future = LocalBoxFuture<'static, Result<Self::Response, Self::Error>>;
+
+        fn poll_ready(&self, _: &mut Context<'_>) -> Poll<Result<(), Self::Error>> {
+            unimplemented!("poll_ready is not used in test")
+        }
+
+        fn call(&self, _: Connect) -> Self::Future {
+            self.generated.set(self.generated.get() + 1);
+            Box::pin(async { Ok((TestStream, Protocol::Http1)) })
+        }
+    }
+
+    #[actix_rt::test]
+    async fn test_pool_limit() {
+        let connector = TestPoolConnector {
+            generated: Rc::new(Cell::new(0)),
+        };
+
+        let mut config = ConnectorConfig::default();
+        config.limit = 1;
+
+        let pool = super::ConnectionPool::new(connector, config);
+
+        let req = Connect {
+            uri: Uri::from_static("http://localhost"),
+            addr: None,
+        };
+
+        let conn = pool.call(req.clone()).await.unwrap();
+
+        let waiting = Rc::new(Cell::new(true));
+
+        let waiting_clone = waiting.clone();
+        actix_rt::spawn(async move {
+            actix_rt::time::sleep(Duration::from_millis(100)).await;
+            waiting_clone.set(false);
+            drop(conn);
+        });
+
+        assert!(waiting.get());
+
+        let now = Instant::now();
+        let conn = pool.call(req.clone()).await.unwrap();
+
+        drop(conn);
+        assert!(!waiting.get());
+        assert!(now.elapsed() >= Duration::from_millis(100));
+    }
+
+    #[actix_rt::test]
+    async fn test_pool_keep_alive() {
+        let generated = Rc::new(Cell::new(0));
+        let generated_clone = generated.clone();
+
+        let connector = TestPoolConnector { generated };
+
+        let mut config = ConnectorConfig::default();
+        config.conn_keep_alive = Duration::from_secs(1);
+
+        let pool = super::ConnectionPool::new(connector, config);
+
+        let req = Connect {
+            uri: Uri::from_static("http://localhost"),
+            addr: None,
+        };
+
+        let conn = pool.call(req.clone()).await.unwrap();
+        assert_eq!(1, generated_clone.get());
+        {
+            let (conn, created, mut acquired) = conn.into_parts();
+            acquired.release(IoConnection::new(conn, created, None));
+        }
+
+        let conn = pool.call(req.clone()).await.unwrap();
+        assert_eq!(1, generated_clone.get());
+        {
+            let (conn, created, mut acquired) = conn.into_parts();
+            acquired.release(IoConnection::new(conn, created, None));
+        }
+
+        actix_rt::time::sleep(Duration::from_millis(1500)).await;
+        actix_rt::task::yield_now().await;
+
+        let conn = pool.call(req.clone()).await.unwrap();
+        assert_eq!(2, generated_clone.get());
+        drop(conn);
+    }
+
+    #[actix_rt::test]
+    async fn test_pool_lifetime() {
+        let generated = Rc::new(Cell::new(0));
+        let generated_clone = generated.clone();
+
+        let connector = TestPoolConnector { generated };
+
+        let mut config = ConnectorConfig::default();
+        config.conn_lifetime = Duration::from_secs(1);
+
+        let pool = super::ConnectionPool::new(connector, config);
+
+        let req = Connect {
+            uri: Uri::from_static("http://localhost"),
+            addr: None,
+        };
+
+        let conn = pool.call(req.clone()).await.unwrap();
+        assert_eq!(1, generated_clone.get());
+        {
+            let (conn, created, mut acquired) = conn.into_parts();
+            acquired.release(IoConnection::new(conn, created, None));
+        }
+
+        let conn = pool.call(req.clone()).await.unwrap();
+        assert_eq!(1, generated_clone.get());
+        {
+            let (conn, created, mut acquired) = conn.into_parts();
+            acquired.release(IoConnection::new(conn, created, None));
+        }
+
+        actix_rt::time::sleep(Duration::from_millis(1500)).await;
+        actix_rt::task::yield_now().await;
+
+        let conn = pool.call(req.clone()).await.unwrap();
+        assert_eq!(2, generated_clone.get());
+        drop(conn);
+    }
+}