feat: favorite actors top-5 stat in profile trends

crates/domain/src/models/tests/stats.rs

@@ -0,0 +1,71 @@
+use super::*;
+
+fn appearance(person_id: u64, name: &str, billing: u32, movie: &str) -> ActorAppearance {
+    ActorAppearance {
+        tmdb_person_id: person_id,
+        name: name.to_string(),
+        profile_path: Some(format!("/profile_{person_id}.jpg")),
+        billing_order: billing,
+        movie_id: movie.to_string(),
+    }
+}
+
+#[test]
+fn empty_appearances_returns_empty() {
+    assert!(compute_top_actors(vec![]).is_empty());
+}
+
+#[test]
+fn lead_scores_higher_than_minor_with_same_movie_count() {
+    let appearances = vec![
+        appearance(1, "Lead Actor", 0, "movie_a"),
+        appearance(1, "Lead Actor", 1, "movie_b"),
+        appearance(2, "Minor Actor", 15, "movie_a"),
+        appearance(2, "Minor Actor", 12, "movie_b"),
+    ];
+    let result = compute_top_actors(appearances);
+    assert_eq!(result.len(), 2);
+    assert_eq!(result[0].name, "Lead Actor");
+    assert_eq!(result[0].movie_count, 2);
+    assert!(result[0].score > result[1].score);
+}
+
+#[test]
+fn same_movie_counted_once_per_actor() {
+    let appearances = vec![
+        appearance(1, "Actor A", 0, "movie_a"),
+        appearance(1, "Actor A", 0, "movie_a"),
+    ];
+    let result = compute_top_actors(appearances);
+    assert_eq!(result[0].movie_count, 1);
+}
+
+#[test]
+fn returns_at_most_five() {
+    let appearances: Vec<ActorAppearance> = (0..10)
+        .flat_map(|i| {
+            (0..=i)
+                .map(move |m| appearance(i as u64, &format!("Actor {i}"), 0, &format!("movie_{m}")))
+        })
+        .collect();
+    let result = compute_top_actors(appearances);
+    assert_eq!(result.len(), 5);
+}
+
+#[test]
+fn tier_weights_applied_correctly() {
+    let appearances = vec![
+        appearance(1, "Lead", 0, "m1"),
+        appearance(2, "Support", 5, "m1"),
+        appearance(2, "Support", 3, "m2"),
+        appearance(3, "Minor", 10, "m1"),
+    ];
+    let result = compute_top_actors(appearances);
+    assert_eq!(result[0].name, "Support");
+    assert!((result[0].score - 1.4).abs() < 0.001);
+    assert_eq!(result[0].movie_count, 2);
+    assert_eq!(result[1].name, "Lead");
+    assert!((result[1].score - 1.0).abs() < 0.001);
+    assert_eq!(result[2].name, "Minor");
+    assert!((result[2].score - 0.2).abs() < 0.001);
+}