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/users/update_profile_fields_test.rs

@@ -0,0 +1,77 @@
+use crate::support::TestContextBuilder;
+use std::sync::Arc;
+
+use domain::events::DomainEvent;
+use domain::models::ProfileField;
+use domain::testing::{InMemoryStore, NoopEventPublisher};
+use uuid::Uuid;
+
+use application::users::{
+    commands::UpdateProfileFieldsCommand, deps::UpdateProfileFieldsDeps, update_profile_fields,
+};
+
+#[tokio::test]
+async fn saves_profile_fields() {
+    let fields_repo = InMemoryStore::new();
+    let events = NoopEventPublisher::new();
+    let b = TestContextBuilder::new()
+        .with_profile_fields(Arc::clone(&fields_repo) as _)
+        .with_event_publisher(Arc::clone(&events) as _);
+    let deps = UpdateProfileFieldsDeps {
+        profile_fields: b.profile_fields_repo.clone(),
+        event_publisher: b.event_publisher.clone(),
+    };
+
+    update_profile_fields::execute(
+        &deps,
+        UpdateProfileFieldsCommand {
+            user_id: Uuid::nil(),
+            fields: vec![
+                ProfileField {
+                    name: "Website".into(),
+                    value: "https://example.com".into(),
+                },
+                ProfileField {
+                    name: "Location".into(),
+                    value: "Berlin".into(),
+                },
+            ],
+        },
+    )
+    .await
+    .unwrap();
+
+    let published = events.published();
+    assert!(
+        published
+            .iter()
+            .any(|e| matches!(e, DomainEvent::UserUpdated { .. }))
+    );
+}
+
+#[tokio::test]
+async fn rejects_more_than_four_fields() {
+    let b = TestContextBuilder::new();
+    let deps = UpdateProfileFieldsDeps {
+        profile_fields: b.profile_fields_repo.clone(),
+        event_publisher: b.event_publisher.clone(),
+    };
+
+    let fields: Vec<ProfileField> = (0..5)
+        .map(|i| ProfileField {
+            name: format!("field{i}"),
+            value: format!("val{i}"),
+        })
+        .collect();
+
+    let result = update_profile_fields::execute(
+        &deps,
+        UpdateProfileFieldsCommand {
+            user_id: Uuid::nil(),
+            fields,
+        },
+    )
+    .await;
+
+    assert!(result.is_err());
+}