1 files changed, 40 insertions, 0 deletions
diff --git a/internal/engine/lifecycle_test.go b/internal/engine/lifecycle_test.go
new file mode 100644
index 0000000..8cea97f
--- /dev/null
+++ b/internal/engine/lifecycle_test.go
@@ -0,0 +1,40 @@
+package engine
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestConcurrentTicksAreSerialized(t *testing.T) {
+	e := New()
+	count := 0
+	e.Subscribe(1, func() bool {
+		count++ // safe only when callbacks have a single owner
+		return true
+	})
+	var wg sync.WaitGroup
+	for i := 0; i < 8; i++ {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for j := 0; j < 100; j++ {
+				e.Tick()
+			}
+		}()
+	}
+	wg.Wait()
+	if count != 800 {
+		t.Fatalf("lost ticks: got %d, want 800", count)
+	}
+}
+
+func TestStopIsIdempotentAndRestartable(t *testing.T) {
+	e := New()
+	e.Stop()
+	defer e.Stop()
+	for i := 0; i < 100; i++ {
+		e.Start(60000)
+		e.Stop()
+		e.Stop()
+	}
+}