package util

import (
	"fmt"
	"sync"
	"testing"
)

func cat(catCh, dogCh chan struct{}, wg *sync.WaitGroup) {
	defer wg.Done()
	for i := 0; i < 100; i++ {
		<-catCh
		fmt.Println("cat", i)
		dogCh <- struct{}{}
	}
}

func dog(dogCh, fishCh chan struct{}, wg *sync.WaitGroup) {
	defer wg.Done()
	for i := 0; i < 100; i++ {
		<-dogCh
		fmt.Println("dog", i)
		fishCh <- struct{}{}
	}
}

func fish(fishCh, catCh chan struct{}, wg *sync.WaitGroup) {
	defer wg.Done()
	for i := 0; i < 100; i++ {
		<-fishCh
		fmt.Println("fish", i)
		catCh <- struct{}{}
	}
}

func Test001(T *testing.T) {
	catCh := make(chan struct{}, 1)
	dogCh := make(chan struct{}, 1)
	fishCh := make(chan struct{}, 1)
	var wg sync.WaitGroup
	wg.Add(3)

	go cat(catCh, dogCh, &wg)
	go dog(dogCh, fishCh, &wg)
	go fish(fishCh, catCh, &wg)

	catCh <- struct{}{}
	wg.Wait()

}