去关闭死锁

Question

正在尝试在 Go 测试中模拟 http 响应。如果我用

运行下面的代码片段永远不会终止

go test example.com/auth/...

package auth_test
import (
    "testing"
    "net/http/httptest"
    "net/http"
)

func TestAuthorization(t *testing.T) {
    t.Log("Should return 401 when Gateway returns 401")
    {
        url := oneOffUrlWithResponseCode(http.StatusUnauthorized)
        request, _ := http.NewRequest("GET", url, nil)
        response, _ := http.DefaultClient.Do(request)

        if response.StatusCode != http.StatusUnauthorized {
            t.Fatalf("Response should be 401 (Unauthorized)")
        }
    }
}

func oneOffUrlWithResponseCode(responseCode int) string {
    var server *httptest.Server
    server = httptest.NewServer(http.HandlerFunc(func(response http.ResponseWriter, request *http.Request) {
        defer server.Close()
        response.WriteHeader(responseCode)
    }))
    return server.URL
}

但是，如果我注释掉这一行

defer server.Close()

一切正常。

理想情况下，我不想 "leak" *httptest.Server 在 oneOffUrlWithResponseCode 函数之外，显然在第一次请求后关闭它。

为什么它永远不会终止？我究竟做错了什么？什么是正确的做法？

Answer 1

程序没有因为死锁而终止（这与闭包无关）。您不能在处理程序内部调用 Close，因为在内部 Close 等待所有处理程序完成。

最简单的修复方法是 "leak" httptest.Server 在 oneOffUrlWithResponseCode 之外：

func TestAuthorization(t *testing.T) {
    ...
    server := oneOffUrlWithResponseCode(http.StatusUnauthorized)
    defer server.Close()
    request, _ := http.NewRequest("GET", server.URL, nil)
    ...
}

func oneOffUrlWithResponseCode(responseCode int) *httptest.Server {
    return httptest.NewServer(http.HandlerFunc(func(response http.ResponseWriter, request *http.Request) {
        response.WriteHeader(responseCode)
    }))
}

去关闭死锁

Go closure deadlock

closures

unit-testing

go