test: move application tests to tests/

test_support/test_helpers -> tests/support; watched_at unified w/ domain test_watched_at (2024-03-15).
Kept inline: users::diary_filter tests (feed_sort_to_direction_all_variants, paged_user_filter_builds_correctly) - pub(super) helpers in private module.
Dropped stale never-compiled users/tests/get_users.rs (old execute signature).

crates/application/tests/services/services_test.rs

@@ -0,0 +1,39 @@
+use crate::support::NoopReviewLogger;
+use application::services::Services;
+use domain::testing::{
+    FakeAuthService, FakeDocumentParser, FakeMetadataClient, FakePasswordHasher, FakePosterFetcher,
+    NoopEventPublisher, NoopObjectStorage, PanicDiaryExporter,
+};
+use std::sync::Arc;
+
+#[test]
+fn services_clone_shares_the_same_port_instances() {
+    let logger: Arc<dyn application::ports::ReviewLogger> = Arc::new(NoopReviewLogger);
+    let s = Services {
+        review_logger: Arc::clone(&logger),
+        person_enrichment: None,
+        auth: Arc::new(FakeAuthService),
+        password_hasher: Arc::new(FakePasswordHasher),
+        metadata: Arc::new(FakeMetadataClient),
+        poster_fetcher: Arc::new(FakePosterFetcher),
+        object_storage: Arc::new(NoopObjectStorage),
+        event_publisher: NoopEventPublisher::new(),
+        diary_exporter: Arc::new(PanicDiaryExporter),
+        document_parser: Arc::new(FakeDocumentParser),
+    };
+
+    let cloned = s.clone();
+
+    assert!(
+        Arc::ptr_eq(&s.review_logger, &cloned.review_logger),
+        "Clone must share port instances, not duplicate them"
+    );
+    assert!(
+        Arc::ptr_eq(&s.review_logger, &logger),
+        "the field must hold the Arc it was given"
+    );
+    assert!(
+        cloned.person_enrichment.is_none(),
+        "optional ports must survive Clone as None"
+    );
+}