我有一個(gè)模塊，它依賴(lài)于通過(guò)調(diào)用外部服務(wù)來(lái)填充緩存，如下所示：func (provider *Cache) GetItem(productId string, skuId string, itemType string) (*Item, error) {    // First, create the key we'll use to uniquely identify the item    key := fmt.Sprintf("%s:%s", productId, skuId)    // Now, attempt to get the concurrency control associated with the item key    // If we couldn't find it then create one and add it to the map    var once *sync.Once    if entry, ok := provider.lockMap.Load(key); ok {        once = entry.(*sync.Once)    } else {        once = &sync.Once{}        provider.lockMap.Store(key, once)    }    // Now, use the concurrency control to attempt to request the item    // but only once. Channel any errors that occur    cErr := make(chan error, 1)    once.Do(func() {        // We didn't find the item in the cache so we'll have to get it from the partner-center        item, err := provider.client.GetItem(productId, skuId)        if err != nil {            cErr <- err            return        }        // Add the item to the cache        provider.cache.Store(key, &item)    })    // Attempt to read an error from the channel; if we get one then return it    // Otherwise, pull the item out of the cache. We have to use the select here because this is    // the only way to attempt to read from a channel without it blocking    var sku interface{}    select {    case err, ok := <-cErr:        if ok {            return nil, err        }    default:        item, _ = provider.cache.Load(key)    }    // Now, pull out a reference to the item and return it    return item.(*Item), nil}這種方法按我的預(yù)期工作。我的問(wèn)題是測(cè)試；專(zhuān)門(mén)測(cè)試以確保該GetItem方法僅針對(duì)給定的鍵值調(diào)用一次。我的測(cè)試代碼如下：var _ = Describe("Item Tests", func() {    It("GetItem - Not cached, two concurrent requests - Client called once", func() {        // setup cache    })})我遇到的問(wèn)題是，有時(shí)這個(gè)測(cè)試會(huì)失敗，因?yàn)檎?qǐng)求計(jì)數(shù)是 2，而在注釋行中預(yù)期它是 1。此故障不一致，我不太確定如何調(diào)試此問(wèn)題。任何幫助將不勝感激。