diff --git a/server/src/connection.rs b/server/src/connection.rs
index dd70056..715ae88 100644
--- a/server/src/connection.rs
+++ b/server/src/connection.rs
@@ -167,3 +167,52 @@ async fn cleanup_player(
 
     println!("Cleaned up player {}", player_id);
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use uuid::Uuid;
+
+    #[tokio::test]
+    async fn test_send_message_to_nonexistent_player() {
+        let connections = new_connection_map();
+        let player_id = Uuid::new_v4();
+
+        let result = send_message_to_player(&connections, player_id, "test message").await;
+        assert!(result.is_ok(), "Should handle missing player gracefully");
+    }
+
+    #[tokio::test]
+    async fn test_broadcast_to_empty_connections() {
+        let connections = new_connection_map();
+
+        broadcast_to_all(&connections, "test broadcast").await;
+
+        let conn_map = connections.lock().await;
+        assert!(conn_map.is_empty(), "Connections should still be empty");
+    }
+
+    #[tokio::test]
+    async fn test_connection_cleanup() {
+        let connections = new_connection_map();
+        let matches = new_match_map();
+        let waiting_queue = new_waiting_queue();
+
+        let player_id = Uuid::new_v4();
+
+        {
+            waiting_queue.lock().await.push_back(player_id);
+            assert_eq!(waiting_queue.lock().await.len(), 1);
+        }
+
+        cleanup_player(player_id, &connections, &matches, &waiting_queue).await;
+
+        {
+            let queue = waiting_queue.lock().await;
+            assert!(
+                !queue.contains(&player_id),
+                "Player should be removed from waiting queue"
+            );
+        }
+    }
+}
diff --git a/server/src/events.rs b/server/src/events.rs
index 0d836b5..8cc43a4 100644
--- a/server/src/events.rs
+++ b/server/src/events.rs
@@ -75,3 +75,52 @@ impl Default for EventSystem {
         Self::new()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use uuid::Uuid;
+
+    #[tokio::test]
+    async fn test_event_system_send_and_receive() {
+        let event_system = EventSystem::new();
+        let player_id = Uuid::new_v4();
+
+        let join_event = ClientEvent::Join {
+            username: "test_user".to_string(),
+        };
+
+        let send_result = event_system.send_event(player_id, join_event).await;
+        assert!(send_result.is_ok(), "Should send event successfully");
+
+        let received = event_system.next_event().await;
+        assert!(received.is_some(), "Should receive sent event");
+
+        let (received_id, received_event) = received.unwrap();
+        assert_eq!(received_id, player_id, "Should receive correct player ID");
+
+        match received_event {
+            ClientEvent::Join { username } => {
+                assert_eq!(username, "test_user", "Should receive correct username");
+            }
+            _ => panic!("Should receive Join event"),
+        }
+    }
+
+    #[tokio::test]
+    async fn test_event_system_clone() {
+        let event_system1 = EventSystem::new();
+        let event_system2 = event_system1.clone();
+
+        let player_id = Uuid::new_v4();
+        let event = ClientEvent::FindMatch;
+
+        event_system1.send_event(player_id, event).await.unwrap();
+
+        let received = event_system2.next_event().await;
+        assert!(
+            received.is_some(),
+            "Cloned event system should receive events"
+        );
+    }
+}
diff --git a/server/src/main.rs b/server/src/main.rs
index ecc9b6f..0d35baf 100644
--- a/server/src/main.rs
+++ b/server/src/main.rs
@@ -1,7 +1,6 @@
 mod connection;
 mod events;
 mod matchmaking;
-
 use tokio::net::TcpListener;
 
 #[tokio::main]
diff --git a/server/src/matchmaking.rs b/server/src/matchmaking.rs
index c2995ba..4f4cc27 100644
--- a/server/src/matchmaking.rs
+++ b/server/src/matchmaking.rs
@@ -110,3 +110,93 @@ impl MatchmakingSystem {
         println!("Match created: {} (white) vs {} (black)", white, black);
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::events::EventSystem;
+    use uuid::Uuid;
+
+    use crate::connection::new_connection_map;
+    use crate::connection::new_match_map;
+    use crate::connection::new_waiting_queue;
+
+    #[tokio::test]
+    async fn test_matchmaking_creates_matches() {
+        let connections = new_connection_map();
+        let matches = new_match_map();
+        let waiting_queue = new_waiting_queue();
+        let event_system = EventSystem::new();
+
+        let matchmaking = MatchmakingSystem::new(
+            connections.clone(),
+            matches.clone(),
+            waiting_queue.clone(),
+            event_system.clone(),
+        );
+
+        let player1 = Uuid::new_v4();
+        let player2 = Uuid::new_v4();
+
+        {
+            waiting_queue.lock().await.push_back(player1);
+            waiting_queue.lock().await.push_back(player2);
+        }
+
+        matchmaking.try_create_match().await;
+
+        {
+            let matches_map = matches.lock().await;
+            assert_eq!(matches_map.len(), 1, "Should create one match");
+
+            let game_match = matches_map.values().next().unwrap();
+            assert!(game_match.player_white == player1 || game_match.player_white == player2);
+            assert!(game_match.player_black == player1 || game_match.player_black == player2);
+            assert_ne!(
+                game_match.player_white, game_match.player_black,
+                "Players should be different"
+            );
+        }
+
+        {
+            let queue = waiting_queue.lock().await;
+            assert!(
+                queue.is_empty(),
+                "Waiting queue should be empty after matchmaking"
+            );
+        }
+    }
+
+    #[tokio::test]
+    async fn test_matchmaking_with_odd_players() {
+        let connections = new_connection_map();
+        let matches = new_match_map();
+        let waiting_queue = new_waiting_queue();
+        let event_system = EventSystem::new();
+
+        let matchmaking = MatchmakingSystem::new(
+            connections.clone(),
+            matches.clone(),
+            waiting_queue.clone(),
+            event_system.clone(),
+        );
+
+        let player1 = Uuid::new_v4();
+        {
+            waiting_queue.lock().await.push_back(player1);
+        }
+
+        matchmaking.try_create_match().await;
+
+        {
+            let matches_map = matches.lock().await;
+            assert!(
+                matches_map.is_empty(),
+                "Should not create match with only one player"
+            );
+
+            let queue = waiting_queue.lock().await;
+            assert_eq!(queue.len(), 1, "Should keep single player in queue");
+        }
+    }
+}