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

crates/arr-subs/tests/opensubtitles.rs

@@ -424,3 +424,42 @@ async fn an_id_this_provider_never_offered_is_not_found() {
         other => panic!("expected NotFound, got {other:?}"),
     }
 }
+
+#[tokio::test]
+async fn a_probe_passes_when_the_key_is_accepted_even_on_a_refused_request() {
+    let server = MockServer::start().await;
+    // An unparseable candidate id is rejected *after* authentication: any
+    // 4xx short of 401/403 is proof the key was accepted, and spends no
+    // search quota (#200).
+    Mock::given(method("GET"))
+        .and(path("/api/v1/subtitles"))
+        .respond_with(ResponseTemplate::new(400))
+        .mount(&server)
+        .await;
+
+    client(&server)
+        .probe()
+        .await
+        .expect("a refused request still proves the key");
+}
+
+#[tokio::test]
+async fn a_probe_reports_refused_credentials_and_outages() {
+    let server = MockServer::start().await;
+    Mock::given(method("GET"))
+        .and(path("/api/v1/subtitles"))
+        .respond_with(ResponseTemplate::new(401))
+        .mount(&server)
+        .await;
+    let err = client(&server).probe().await.expect_err("bad key");
+    assert!(matches!(err, Error::Unauthorized { .. }));
+
+    server.reset().await;
+    Mock::given(method("GET"))
+        .and(path("/api/v1/subtitles"))
+        .respond_with(ResponseTemplate::new(500))
+        .mount(&server)
+        .await;
+    let err = client(&server).probe().await.expect_err("outage");
+    assert!(matches!(err, Error::Malformed { .. }));
+}