Added some tests at least for the broadcast buffering.

src/event_manager.rs

@@ -6,7 +6,7 @@ use tokio::{
     net::{UnixListener, UnixStream},
     sync::{RwLock, broadcast},
 };
-use tracing::error;
+use tracing::{error, info};
 
 use crate::event::Event;
 
@@ -51,7 +51,8 @@ impl EventManager {
 
         loop {
             match listener.accept().await {
-                Ok((stream, _)) => {
+                Ok((stream, _addr)) => {
+                    info!("New broadcast subscriber");
                     // Spawn a new stream for the plugin.  The loop
                     // runs recursively from there.
                     let broadcaster = Arc::clone(&self);
@@ -87,3 +88,188 @@ impl EventManager {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use rstest::rstest;
+
+    #[tokio::test]
+    async fn test_new_event_manager_has_empty_buffer() {
+        let manager = EventManager::new().unwrap();
+        let events = manager.events.read().await;
+        assert_eq!(events.len(), 0);
+    }
+
+    #[tokio::test]
+    async fn test_broadcast_adds_event_to_buffer() {
+        let manager = EventManager::new().unwrap();
+        let event = Event::new("test message");
+
+        manager.broadcast(&event).await.unwrap();
+
+        let events = manager.events.read().await;
+        assert_eq!(events.len(), 1);
+        assert!(events[0].contains("test message"));
+        assert!(events[0].ends_with('\n'));
+    }
+
+    #[tokio::test]
+    async fn test_broadcast_serializes_event_as_json() {
+        let manager = EventManager::new().unwrap();
+        let event = Event::new("hello world");
+
+        manager.broadcast(&event).await.unwrap();
+
+        let events = manager.events.read().await;
+        let stored = &events[0];
+
+        // Should be valid JSON
+        let parsed: serde_json::Value = serde_json::from_str(stored.trim()).unwrap();
+        assert_eq!(parsed["message"], "hello world");
+    }
+
+    #[rstest]
+    #[case(1)]
+    #[case(10)]
+    #[case(100)]
+    #[case(999)]
+    #[tokio::test]
+    async fn test_buffer_holds_events_below_max(#[case] count: usize) {
+        let manager = EventManager::new().unwrap();
+
+        for i in 0..count {
+            let event = Event::new(format!("event {}", i));
+            manager.broadcast(&event).await.unwrap();
+        }
+
+        let events = manager.events.read().await;
+        assert_eq!(events.len(), count);
+    }
+
+    #[tokio::test]
+    async fn test_buffer_at_exactly_max_capacity() {
+        let manager = EventManager::new().unwrap();
+
+        // Fill to exactly EVENT_BUF_MAX (1000)
+        for i in 0..EVENT_BUF_MAX {
+            let event = Event::new(format!("event {}", i));
+            manager.broadcast(&event).await.unwrap();
+        }
+
+        let events = manager.events.read().await;
+        assert_eq!(events.len(), EVENT_BUF_MAX);
+        assert!(events[0].contains("event 0"));
+        assert!(events[EVENT_BUF_MAX - 1].contains("event 999"));
+    }
+
+    #[rstest]
+    #[case(1)]
+    #[case(10)]
+    #[case(100)]
+    #[case(500)]
+    #[tokio::test]
+    async fn test_buffer_overflow_evicts_oldest_fifo(#[case] overflow: usize) {
+        let manager = EventManager::new().unwrap();
+        let total = EVENT_BUF_MAX + overflow;
+
+        // Broadcast more events than buffer can hold
+        for i in 0..total {
+            let event = Event::new(format!("event {}", i));
+            manager.broadcast(&event).await.unwrap();
+        }
+
+        let events = manager.events.read().await;
+
+        // Buffer should still be at max capacity
+        assert_eq!(events.len(), EVENT_BUF_MAX);
+
+        // Oldest events (0 through overflow-1) should be evicted
+        // Buffer should contain events [overflow..total)
+        let first_event = &events[0];
+        let last_event = &events[EVENT_BUF_MAX - 1];
+
+        assert!(first_event.contains(&format!("event {}", overflow)));
+        assert!(last_event.contains(&format!("event {}", total - 1)));
+
+        // Verify the evicted events are NOT in the buffer
+        let buffer_string = events.iter().cloned().collect::<String>();
+        assert!(!buffer_string.contains(r#""message":"event 0""#));
+    }
+
+    #[tokio::test]
+    async fn test_multiple_broadcasts_maintain_order() {
+        let manager = EventManager::new().unwrap();
+        let messages = vec!["first", "second", "third", "fourth", "fifth"];
+
+        for msg in &messages {
+            let event = Event::new(*msg);
+            manager.broadcast(&event).await.unwrap();
+        }
+
+        let events = manager.events.read().await;
+        assert_eq!(events.len(), messages.len());
+
+        for (i, expected) in messages.iter().enumerate() {
+            assert!(events[i].contains(expected));
+        }
+    }
+
+    #[tokio::test]
+    async fn test_buffer_wraparound_maintains_newest_events() {
+        let manager = EventManager::new().unwrap();
+
+        // Fill buffer completely
+        for i in 0..EVENT_BUF_MAX {
+            let event = Event::new(format!("old {}", i));
+            manager.broadcast(&event).await.unwrap();
+        }
+
+        // Add 5 more events
+        for i in 0..5 {
+            let event = Event::new(format!("new {}", i));
+            manager.broadcast(&event).await.unwrap();
+        }
+
+        let events = manager.events.read().await;
+        assert_eq!(events.len(), EVENT_BUF_MAX);
+
+        // First 5 old events should be gone
+        let buffer_string = events.iter().cloned().collect::<String>();
+        assert!(!buffer_string.contains(r#""message":"old 0""#));
+        assert!(!buffer_string.contains(r#""message":"old 4""#));
+
+        // But old 5 should still be there (now at the front)
+        assert!(events[0].contains("old 5"));
+
+        // New events should be at the end
+        assert!(events[EVENT_BUF_MAX - 5].contains("new 0"));
+        assert!(events[EVENT_BUF_MAX - 1].contains("new 4"));
+    }
+
+    #[tokio::test]
+    async fn test_concurrent_broadcasts_all_stored() {
+        let manager = Arc::new(EventManager::new().unwrap());
+        let mut handles = vec![];
+
+        // Spawn 10 concurrent tasks, each broadcasting 10 events
+        for task_id in 0..10 {
+            let manager_clone = Arc::clone(&manager);
+            let handle = tokio::spawn(async move {
+                for i in 0..10 {
+                    let event = Event::new(format!("task {} event {}", task_id, i));
+                    manager_clone.broadcast(&event).await.unwrap();
+                }
+            });
+            handles.push(handle);
+        }
+
+        // Wait for all tasks to complete
+        for handle in handles {
+            handle.await.unwrap();
+        }
+
+        let events = manager.events.read().await;
+        assert_eq!(events.len(), 100);
+    }
+}