feat(domain): ports, events, test helpers

crates/domain/src/events.rs

@@ -1 +1,28 @@
-// filled in Task 4
+use crate::value_objects::{UserId, ThoughtId, LikeId, BoostId};
+
+#[derive(Debug, Clone)]
+pub enum DomainEvent {
+    ThoughtCreated { thought_id: ThoughtId, user_id: UserId, in_reply_to_id: Option<ThoughtId> },
+    ThoughtDeleted { thought_id: ThoughtId, user_id: UserId },
+    ThoughtUpdated { thought_id: ThoughtId, user_id: UserId },
+    LikeAdded    { like_id: LikeId, user_id: UserId, thought_id: ThoughtId },
+    LikeRemoved  { user_id: UserId, thought_id: ThoughtId },
+    BoostAdded   { boost_id: BoostId, user_id: UserId, thought_id: ThoughtId },
+    BoostRemoved { user_id: UserId, thought_id: ThoughtId },
+    FollowRequested { follower_id: UserId, following_id: UserId },
+    FollowAccepted  { follower_id: UserId, following_id: UserId },
+    FollowRejected  { follower_id: UserId, following_id: UserId },
+    Unfollowed   { follower_id: UserId, following_id: UserId },
+    UserBlocked  { blocker_id: UserId, blocked_id: UserId },
+}
+
+pub struct EventEnvelope {
+    pub event: DomainEvent,
+    pub ack:  Box<dyn Fn() + Send + Sync>,
+    pub nack: Box<dyn Fn() + Send + Sync>,
+}
+impl std::fmt::Debug for EventEnvelope {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("EventEnvelope").field("event", &self.event).finish()
+    }
+}