add test

cron_test.go

@@ -1,7 +1,19 @@
 package startimer
 
-import "testing"
+import (
+	"fmt"
+	"testing"
+	"time"
+)
 
 func TestParseCron(t *testing.T) {
-	parseCron("0 */4 *  *  *   *")
+	r, err := NewTimerWithSecCron("0 */4 *  *  *   *")
+	if err != nil {
+		t.Fatal(err)
+	}
+	base := time.Now()
+	for i := 0; i < 20; i++ {
+		base = r.NextTimerAfterDate(base)
+		fmt.Println(base)
+	}
 }