Get a basic first test working, and lots of changes to supporting code to facilitate this

backend/telemetry_core/tests/basic_tests.rs

@@ -0,0 +1,27 @@
+use test_utils::{feed_message_de::FeedMessage, server::Server};
+// use serde_json::json;
+
+#[tokio::test]
+async fn can_ping_feed() {
+
+    let server = Server::start_default()
+        .await
+        .expect("server could start");
+
+    // Connect to the feed:
+    let (mut feed_tx, mut feed_rx) = server.get_core().connect().await.unwrap();
+
+    // Expect a version response of 31:
+    let feed_messages = feed_rx.recv_feed_messages().await.unwrap();
+    assert_eq!(feed_messages, vec![FeedMessage::Version(31)], "expecting version");
+
+    // Ping it:
+    feed_tx.send_command("ping", "hello!").await.unwrap();
+
+    // Expect a pong response:
+    let feed_messages = feed_rx.recv_feed_messages().await.unwrap();
+    assert_eq!(feed_messages, vec![FeedMessage::Pong { msg: "hello!".to_owned() }], "expecting pong");
+
+    // Tidy up:
+    server.shutdown().await;
+}