feat(arr): probe methods for subtitle providers and engines

crates/arr-subs/tests/podnapisi.rs

@@ -282,3 +282,26 @@ async fn an_id_this_provider_never_issued_is_not_found() {
 
     assert!(matches!(error, Error::NotFound { .. }), "got {error:?}");
 }
+
+#[tokio::test]
+async fn a_probe_is_reachability_alone() {
+    let server = MockServer::start().await;
+    Mock::given(method("GET"))
+        .and(path("/subtitles/"))
+        .respond_with(ResponseTemplate::new(200))
+        .mount(&server)
+        .await;
+    provider(&server)
+        .probe()
+        .await
+        .expect("the anonymous provider is up when the site answers");
+
+    server.reset().await;
+    Mock::given(method("GET"))
+        .and(path("/subtitles/"))
+        .respond_with(ResponseTemplate::new(500))
+        .mount(&server)
+        .await;
+    let error = provider(&server).probe().await.expect_err("site down");
+    assert!(matches!(error, Error::Malformed { .. }), "got {error:?}");
+}