如何在读取响应正文时强加错误 [英] How to force error on reading response body
问题描述
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.
I've written http client wrapper in go and I need to test it thoroughly. I'm reading the response body with ioutil.ReadAll within the wrapper. I'm having a bit of trouble figuring out how I can force a read from the response body to fail with the help of httptest.
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:
I'm assuming I can set up a fake server as such:
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?
I'm assuming I need to modify the ResposeWriter. Now, is there any way for me to modify the responseWriter and thereby force the ioutil.ReadAll in the wrapper to fail?
I realize that you seem to think it's a duplicate of this post and while you may believe so or it might be, just marking it as a duplicate doesn't really help me. The code provided in the answers in the "duplicate" post makes very little sense to me in this context.
推荐答案
检查 Response.Body 以查看何时从中读取可能会返回错误:
Check the documentation of Response.Body to see when reading from it might return an error:
// 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.
The easiest way is to generate an invalid HTTP response from the test handler.
该怎么做?有很多方法，一种简单的方法是撒谎"内容的长度:
How to do that? There are many ways, a simple one is to "lie" about the content length:
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:
This handler tells it has 1 byte body, but actually it sends none. So at the other end (the client) when attempting to read 1 byte from it, obviously that won't succeed, and will result in the following error:
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)读取错误:
See related question if you would need to simulate error reading from a request body (not from a response body): How do I test an error on reading from a request body?
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