diff --git a/backend/shared/domain/events/event_test.go b/backend/shared/domain/events/event_test.go
index 553a9af..0d3ffc4 100644
--- a/backend/shared/domain/events/event_test.go
+++ b/backend/shared/domain/events/event_test.go
@@ -3,6 +3,7 @@ package events
 // Tests for event base fields and event type string behavior.
 
 import (
+	"context"
 	"testing"
 	"time"
 
@@ -26,3 +27,39 @@ func TestNewBaseEvent(t *testing.T) {
 func TestEventType_String(t *testing.T) {
 	require.Equal(t, "game_session.started", GameSessionStarted.String())
 }
+
+// TestEventType_NonEmpty ensures all event type constants are non-empty strings.
+func TestEventType_NonEmpty(t *testing.T) {
+	types := []EventType{
+		GameSessionStarted,
+		GameSessionEnded,
+		GameSessionTimedOut,
+		AnswerSubmitted,
+		HintRequested,
+		QuestionAnswered,
+		UserRegistered,
+		UserEmailVerified,
+		UserDeleted,
+		QuestionCreated,
+		QuestionUpdated,
+		QuestionDeleted,
+		ScoreUpdated,
+		LeaderboardRefreshed,
+	}
+
+	for _, eventType := range types {
+		require.NotEmpty(t, eventType.String())
+	}
+}
+
+type dummyEventBus struct{}
+
+func (d *dummyEventBus) Publish(_ context.Context, _ Event) error {
+	return nil
+}
+
+func (d *dummyEventBus) Subscribe(_ EventHandler) error {
+	return nil
+}
+
+var _ EventBus = (*dummyEventBus)(nil)