add ut for spinlock

spinlock_test.go

@@ -0,0 +1,37 @@
+package rollingwriter
+
+import (
+	"sync"
+	"testing"
+)
+
+func TestSpinLock(t *testing.T) {
+	var counter int
+	var wg sync.WaitGroup
+	spinLock := &Locker{}
+
+	startCh := make(chan struct{})
+
+	wg.Add(5000)
+	for i := 0; i < 5000; i++ {
+		go func() {
+			defer wg.Done()
+
+			// waitting start
+			<-startCh
+
+			for j := 0; j < 10000; j++ {
+				spinLock.Lock()
+				counter++
+				spinLock.Unlock()
+			}
+		}()
+	}
+
+	close(startCh)
+	wg.Wait()
+
+	if counter != 50000000 {
+		t.Errorf("Counter should be 50000000, but got %d", counter)
+	}
+}