测试Go http.Request.FormFile？

Question

如何在尝试测试端点时设置Request.FormFile？

部分代码：

func (a *EP) Endpoint(w http.ResponseWriter, r *http.Request) {
    ...

    x, err := strconv.Atoi(r.FormValue("x"))
    if err != nil {
        a.ren.Text(w, http.StatusInternalServerError, err.Error())
        return
    }

    f, fh, err := r.FormFile("y")
    if err != nil {
        a.ren.Text(w, http.StatusInternalServerError, err.Error())
        return
    }
    defer f.Close()
    ...
}

如何使用httptest lib生成具有可以在FormFile中获取的值的post请求？

Answer 1

您不需要按照另一个答案的建议模拟完整的FormFile结构。mime/multipart包实现了一个允许您创建FormFile的写入器类型。来自the docs

CreateFormFile是CreatePart的便捷包装器。它使用提供的字段名和文件名创建一个新的表单数据标题。

func (w *Writer) CreateFormFile(fieldname, filename string) (io.Writer, error)

然后，您可以将此io.Writer传递给httptest.NewRequest，它接受一个读取器作为参数。

request := httptest.NewRequest("POST", "/", myReader)

为此，您可以将FormFile写入io.ReaderWriter缓冲区或使用io.Pipe。下面是一个使用管道的完整示例：

func TestUploadImage(t *testing.T) {
    //Set up a pipe to avoid buffering
    pr, pw := io.Pipe()
    //This writers is going to transform 
    //what we pass to it to multipart form data
    //and write it to our io.Pipe
    writer := multipart.NewWriter(pw)

    go func() {
        defer writer.Close()
        //we create the form data field 'fileupload'
        //wich returns another writer to write the actual file 
        part, err := writer.CreateFormFile("fileupload", "someimg.png")
        if err != nil {
            t.Error(err)
        }

        //https://yourbasic.org/golang/create-image/
        img := createImage()

        //Encode() takes an io.Writer.
        //We pass the multipart field
        //'fileupload' that we defined
        //earlier which, in turn, writes
        //to our io.Pipe
        err = png.Encode(part, img)
        if err != nil {
            t.Error(err)
        }
    }()

    //We read from the pipe which receives data
    //from the multipart writer, which, in turn,
    //receives data from png.Encode().
    //We have 3 chained writers !
    request := httptest.NewRequest("POST", "/", pr)
    request.Header.Add("Content-Type", writer.FormDataContentType())

    response := httptest.NewRecorder()
    handler := UploadFileHandler()
    handler.ServeHTTP(response, request)

    t.Log("It should respond with an HTTP status code of 200")
    if response.Code != 200 {
        t.Errorf("Expected %s, received %d", 200, response.Code)
    }
    t.Log("It should create a file named 'someimg.png' in uploads folder")
    if _, err := os.Stat("./uploads/someimg.png"); os.IsNotExist(err) {
        t.Error("Expected file ./uploads/someimg.png' to exist")
    }
}

此函数利用image包动态生成一个文件，利用您可以将io.Writer传递给png.Encode这一事实。同样地，你可以通过你的多部分写入器来生成CSV格式的字节(在包“NewWriter/csv”中的编码)，动态地生成一个文件，而不需要从你的文件系统中读取任何东西。

Answer 2

如果您查看了FormFile函数的实现，就会看到它读取了公开的MultipartForm字段。

https://golang.org/src/net/http/request.go?s=39022:39107#L1249

        // FormFile returns the first file for the provided form key.
  1258  // FormFile calls ParseMultipartForm and ParseForm if necessary.
  1259  func (r *Request) FormFile(key string) (multipart.File, *multipart.FileHeader, error) {
  1260      if r.MultipartForm == multipartByReader {
  1261          return nil, nil, errors.New("http: multipart handled by MultipartReader")
  1262      }
  1263      if r.MultipartForm == nil {
  1264          err := r.ParseMultipartForm(defaultMaxMemory)
  1265          if err != nil {
  1266              return nil, nil, err
  1267          }
  1268      }
  1269      if r.MultipartForm != nil && r.MultipartForm.File != nil {
  1270          if fhs := r.MultipartForm.File[key]; len(fhs) > 0 {
  1271              f, err := fhs[0].Open()
  1272              return f, fhs[0], err
  1273          }
  1274      }
  1275      return nil, nil, ErrMissingFile
  1276  }

在测试中，您应该能够创建multipart.Form的测试实例并将其分配给请求对象-- https://golang.org/pkg/mime/multipart/#Form

type Form struct {
        Value map[string][]string
        File  map[string][]*FileHeader
}

当然，这将要求您使用真正的文件路径，这从测试的角度来看并不是很好。要解决这个问题，可以定义一个接口来从请求对象中读取FormFile，并将模拟实现传递到EP结构中。

这里有一个很好的帖子，里面有几个关于如何做到这一点的例子：https://husobee.github.io/golang/testing/unit-test/2015/06/08/golang-unit-testing.html

Answer 3

我将这些答案和其他答案组合到一个没有管道或goroutines的Echo示例中：

func Test_submitFile(t *testing.T) {
    path := "testfile.txt"

    body := new(bytes.Buffer)
    writer := multipart.NewWriter(body)
    part, err := writer.CreateFormFile("object", path)
    assert.NoError(t, err)
    sample, err := os.Open(path)
    assert.NoError(t, err)

    _, err = io.Copy(part, sample)
    assert.NoError(t, err)
    assert.NoError(t, writer.Close())

    e := echo.New()
    req := httptest.NewRequest(http.MethodPost, "/", body)
    req.Header.Set(echo.HeaderContentType, writer.FormDataContentType()) 
    rec := httptest.NewRecorder()
    c := e.NewContext(req, rec)
    c.SetPath("/submit")
    if assert.NoError(t, submitFile(c)) {
        assert.Equal(t, 200, rec.Code)
        assert.Contains(t, rec.Body.String(), path)
        fi, err := os.Stat(expectedPath)
        if os.IsNotExist(err) {
            t.Fatal("Upload file does not exist", expectedPath)
        }
        assert.Equal(t, wantSize, fi.Size())
    }
}