Question

我已经在go中编写了http客户端包装程序，我需要对其进行彻底的测试。我正在使用包装器中的ioutil.ReadAll阅读响应正文。我在弄清楚如何在httptest的帮助下如何强制从响应正文读取失败时遇到了麻烦。

package req

func GetContent(url string) ([]byte, error) {
    response, err := httpClient.Get(url)
    // some header validation goes here
    body, err := ioutil.ReadAll(response.Body)
    defer response.Body.Close()

    if err != nil {
        errStr := fmt.Sprintf("Unable to read from body %s", err)
        return nil, errors.New(errStr)
    }

    return body, nil
}

我假设我可以像这样设置一个假服务器：

package req_test

func Test_GetContent_RequestBodyReadError(t *testing.T) {

    handler := func(w http.ResponseWriter, r *http.Request) {
        w.WriteHeader(http.StatusOK)
    }

    ts := httptest.NewServer(http.HandlerFunc(handler))
    defer ts.Close()

    _, err := GetContent(ts.URL)

    if err != nil {
        t.Log("Body read failed as expected.")
    } else {
        t.Fatalf("Method did not fail as expected")
    }

}

我假设我需要修改ResposeWriter。现在，有什么方法可以修改responseWriter，从而迫使包装器中的ioutil.ReadAll失败吗？

我意识到您似乎认为它是this post的副本，虽然您可能会这样认为，也可能是这样，但仅将其标记为副本并不能真正帮助我。在这种情况下，“重复”帖子中答案中提供的代码对我来说意义不大。

Answer 1

检查Response.Body的文档以了解何时从中读取可能会返回错误：

// Body represents the response body.
//
// The response body is streamed on demand as the Body field
// is read. If the network connection fails or the server
// terminates the response, Body.Read calls return an error.
//
// The http Client and Transport guarantee that Body is always
// non-nil, even on responses without a body or responses with
// a zero-length body. It is the caller's responsibility to
// close Body. The default HTTP client's Transport may not
// reuse HTTP/1.x "keep-alive" TCP connections if the Body is
// not read to completion and closed.
//
// The Body is automatically dechunked if the server replied
// with a "chunked" Transfer-Encoding.
Body io.ReadCloser

最简单的方法是从测试处理程序生成无效的HTTP响应。

该怎么做？有很多方法，一种简单的方法是“撒谎”内容的长度：

handler := func(w http.ResponseWriter, r *http.Request) {
    w.Header().Set("Content-Length", "1")
}

此处理程序告诉它具有1个字节的正文，但实际上它不发送任何字节。因此，在另一端（客户端）尝试从中读取1个字节时，显然不会成功，并且会导致以下错误：

Unable to read from body unexpected EOF

请参见相关问题，是否需要模拟从请求正文（而不是响应正文）中读取错误：How do I test an error on reading from a request body?

Answer 2

要扩展icza的出色答案，您也可以使用httptest.Server对象：

bodyErrorServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  w.Header().Set("Content-Length", "1")
}))

defer bodyErrorServer.Close()

然后，您可以像平常一样在测试中通过bodyErrorServer.URL，您将始终收到EOF错误：

package main

import (
    "bytes"
    "fmt"
    "io/ioutil"
    "net/http"
    "net/http/httptest"
    "testing"
    "time"
)

func getBodyFromURL(service string, clientTimeout int) (string, error) {

    var netClient = &http.Client{
        Timeout: time.Duration(clientTimeout) * time.Millisecond,
    }

    rsp, err := netClient.Get(service)
    if err != nil {
        return "", err
    }

    defer rsp.Body.Close()

    if rsp.StatusCode != 200 {
        return "", fmt.Errorf("HTTP request error. Response code: %d", rsp.StatusCode)
    }

    buf, err := ioutil.ReadAll(rsp.Body)
    if err != nil {
        return "", err
    }

    return string(bytes.TrimSpace(buf)), nil
}

func TestBodyError(t *testing.T) {

    bodyErrorServer := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
        w.Header().Set("Content-Length", "1")
    }))

    _, err := getBodyFromURL(bodyErrorServer.URL, 1000)

    if err.Error() != "unexpected EOF" {
        t.Error("GOT AN ERROR")
    } else if err == nil {
            t.Error("GOT NO ERROR, THATS WRONG!")
    } else {
        t.Log("Got an unexpected EOF as expected, horray!")
    }
}

此处的游乐场示例：https://play.golang.org/p/JzPmatibgZn

如何在读取响应正文时强加错误

2 个答案: