我正试图为配置github.com/Shopify/sarama的Logger的功能选项编写一个单元测试。在使用Kafka运行Docker容器之后，
docker run -p 2181:2181 -p 9092:9092 -e ADVERTISED_HOST=127.0.0.1 -e NUM_PARTITIONS=10 johnnypark/kafka-zookeeper
我正在尝试运行这个程序：
package main
import (
"bufio"
"bytes"
"io/ioutil"
"log"
"github.com/Shopify/sarama"
)
func main() {
var b bytes.Buffer
out := bufio.NewWriter(&b)
sarama.Logger = log.New(out, "[Sarama] ", log.LstdFlags)
if _, err := sarama.NewClient([]string{"localhost:9092"}, sarama.NewConfig()); err != nil {
log.Fatalln("NewClient:", err)
}
output, err := ioutil.ReadAll(&b)
if err != nil {
log.Fatalln("ReadAll:", err)
}
log.Printf("output: %s", output)
}
我希望看到一些产出。但是，打印输出为空：
> go run main.go
2020/09/25 16:44:58 output:
相反，如果我将输出设置为os.Stderr，
package main
import (
"log"
"os"
"github.com/Shopify/sarama"
)
func main() {
sarama.Logger = log.New(os.Stderr, "[Sarama] ", log.LstdFlags)
if _, err := sarama.NewClient([]string{"localhost:9092"}, sarama.NewConfig()); err != nil {
log.Fatalln("NewClient:", err)
}
}
我看到打印到终端的预期输出：
> go run main.go
[Sarama] 2020/09/25 16:46:04 Initializing new client
[Sarama] 2020/09/25 16:46:04 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
[Sarama] 2020/09/25 16:46:04 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
[Sarama] 2020/09/25 16:46:04 client/metadata fetching metadata for all topics from broker localhost:9092
[Sarama] 2020/09/25 16:46:04 Connected to broker at localhost:9092 (unregistered)
[Sarama] 2020/09/25 16:46:04 client/brokers registered new broker #0 at 127.0.0.1:9092
[Sarama] 2020/09/25 16:46:04 Successfully initialized new client
*bytes.Buffer似乎没有被ioutil.ReadAll()"刷新"？如何修复前面的示例，使output不为空？
原来我只需要调用
out.Flush()
在CCD_ 7之前。现在输出如预期：
> go run main.go
2020/09/25 16:58:26 output: [Sarama] 2020/09/25 16:58:26 Initializing new client
[Sarama] 2020/09/25 16:58:26 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
[Sarama] 2020/09/25 16:58:26 ClientID is the default of 'sarama', you should consider setting it to something application-specific.
[Sarama] 2020/09/25 16:58:26 client/metadata fetching metadata for all topics from broker localhost:9092
[Sarama] 2020/09/25 16:58:26 Connected to broker at localhost:9092 (unregistered)
[Sarama] 2020/09/25 16:58:26 client/brokers registered new broker #0 at 127.0.0.1:9092
[Sarama] 2020/09/25 16:58:26 Successfully initialized new client