test(postgres): add list_mutual integration tests

crates/adapters/postgres/src/follow/tests.rs

@@ -56,3 +56,86 @@ async fn get_accepted_following_ids(pool: sqlx::PgPool) {
     let ids = repo.get_accepted_following_ids(&alice.id).await.unwrap();
     assert_eq!(ids, vec![bob.id]);
 }
+
+#[sqlx::test(migrations = "./migrations")]
+async fn list_mutual_returns_only_mutual_accepted_follows(pool: sqlx::PgPool) {
+    let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+    let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+    let carol = seed_user(&pool, "carol", "carol@ex.com").await;
+    let repo = PgFollowRepository::new(pool);
+    let page = domain::models::feed::PageParams {
+        page: 1,
+        per_page: 20,
+    };
+
+    // alice → bob (accepted), bob → alice (accepted) = friends
+    repo.save(&Follow {
+        follower_id: alice.id.clone(),
+        following_id: bob.id.clone(),
+        state: FollowState::Accepted,
+        ap_id: None,
+        created_at: Utc::now(),
+    })
+    .await
+    .unwrap();
+    repo.save(&Follow {
+        follower_id: bob.id.clone(),
+        following_id: alice.id.clone(),
+        state: FollowState::Accepted,
+        ap_id: None,
+        created_at: Utc::now(),
+    })
+    .await
+    .unwrap();
+
+    // alice → carol (accepted), carol does NOT follow back = not a friend
+    repo.save(&Follow {
+        follower_id: alice.id.clone(),
+        following_id: carol.id.clone(),
+        state: FollowState::Accepted,
+        ap_id: None,
+        created_at: Utc::now(),
+    })
+    .await
+    .unwrap();
+
+    let result = repo.list_mutual(&alice.id, &page).await.unwrap();
+    assert_eq!(result.total, 1);
+    assert_eq!(result.items.len(), 1);
+    assert_eq!(result.items[0].id, bob.id);
+}
+
+#[sqlx::test(migrations = "./migrations")]
+async fn list_mutual_excludes_pending_follows(pool: sqlx::PgPool) {
+    let alice = seed_user(&pool, "alice", "alice@ex.com").await;
+    let bob = seed_user(&pool, "bob", "bob@ex.com").await;
+    let repo = PgFollowRepository::new(pool);
+    let page = domain::models::feed::PageParams {
+        page: 1,
+        per_page: 20,
+    };
+
+    // alice → bob (accepted), bob → alice (PENDING) = NOT a friend
+    repo.save(&Follow {
+        follower_id: alice.id.clone(),
+        following_id: bob.id.clone(),
+        state: FollowState::Accepted,
+        ap_id: None,
+        created_at: Utc::now(),
+    })
+    .await
+    .unwrap();
+    repo.save(&Follow {
+        follower_id: bob.id.clone(),
+        following_id: alice.id.clone(),
+        state: FollowState::Pending,
+        ap_id: None,
+        created_at: Utc::now(),
+    })
+    .await
+    .unwrap();
+
+    let result = repo.list_mutual(&alice.id, &page).await.unwrap();
+    assert_eq!(result.total, 0);
+    assert!(result.items.is_empty());
+}