Try to abstract the main part.

code/test/main_test.go

@@ -26,6 +26,9 @@ func TestCron(t *testing.T) {
 	err := c.AddFunc(spec, func() {
 		i++
 		log.Println("cron running:", i)
+		if i == 2 {
+			panic("intent to panic.")
+		}
 	})
 	util.PanicError(err)