Golang的模拟强制改变函数定义。

huangapple
go评论123阅读模式
英文:

Golang mock forces to change functions definition

问题

我有以下函数：

  1. func getPrice(date string) {
  2.   url := (fmt.Printf("http://endponint/%s", date))
  3. 	resp, err := http.Get(url)
  4. 	// 解析响应体并获取价格
  5. 	return price
  6. }

为了对这个函数进行单元测试，我被迫进行重构：

  1. func getPrice(client HTTPClient, date string) {
  2.   url := (fmt.Printf("http://endponint/%s", date))
  3. 	resp, err := client.Get(url)
  4. 	// 解析响应体并获取价格
  5. 	return price
  6. }

我的测试代码如下：

  1. type MockClient struct {
  2. 	Response *http.Response
  3. 	Err      error
  4. }
  6. func (m *MockClient) Get(url string) (*http.Response, error) {
  7. 	return m.Response, m.Err
  8. }
  10. mockResp := &http.Response{
  11. 	StatusCode: http.StatusOK,
  12. 	Body:       ioutil.NopCloser(strings.NewReader("mock response")),
  13. }
  15. client := &MockClient{
  16. 	Response: mockResp,
  17. 	Err:      nil,
  18. }
  20. data, err := getData(client, "http://example.com")

这是在Go语言中测试的唯一方法吗？没有办法模拟未注入函数的API吗？

英文:

I have the following function:

  1. func getPrice(date string) {
  2.   url := (fmt.Printf("http://endponint/%s", date))
  3. 	resp, err := http.Get(url)
  4. 	// Unmarshall body and get price
  5. 	return price
  6. }

In order to unit test this function I'm forced to refactor to:

  1. func getPrice(client HTTPClient, date string) {
  2.   url := (fmt.Printf("http://endponint/%s", date))
  3. 	resp, err := client.Get(url)
  4. 	// Unmarshall body and get price
  5. 	return price
  6. }

And my test looks like this:

  2. type MockClient struct {
  3. 	Response *http.Response
  4. 	Err      error
  5. }
  7. func (m *MockClient) Get(url string) (*http.Response, error) {
  8. 	return m.Response, m.Err
  9. }
  11. mockResp := &http.Response{
  12. 	StatusCode: http.StatusOK,
  13. 	Body:       ioutil.NopCloser(strings.NewReader("mock response")),
  14. }
  16. client := &MockClient{
  17. 	Response: mockResp,
  18. 	Err:      nil,
  19. }
  21. data, err := getData(client, "http://example.com")

Is this only way to test in Go, is there no way to mock an API which is not injected into function?

答案1

得分: 1

使用Go进行HTTP测试的惯用方法是使用http/httptest（示例）。

在你的情况下，你只需要使基本URL可注入：

  1. var APIEndpoint = "http://endpoint/"
  3. func getPrice(date string) (int, error) {
  4.   url := (fmt.Printf("%s/%s", APIEndpoint, date))
  5.   resp, err := http.Get(url)
  6.   // 反序列化响应体并获取价格
  7.   return price, nil
  8. }

然后在每个测试中：

  1. srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  2. 	// 将预期的响应写入writer
  3. }))
  4. defer srv.Close()
  5. APIEndpoint = srv.URL
  6. price, err := getPrice("1/1/2023")
  7. // 处理错误，检查返回值

稍微更好的设计是将你的API封装在一个客户端struct中，并将getPrice作为接收器方法：

  1. type PriceClient struct {
  2.     Endpoint string
  3. }
  5. func (pc *PriceClient) GetPrice(date string) (int, error) {
  6.   url := (fmt.Printf("%s/%s", pc.Endpoint, date))
  7.   resp, err := http.Get(url)
  8.   // 反序列化响应体并获取价格
  9.   return price, nil
  10. }
  1. srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  2. 	// 将预期的响应写入writer
  3. }))
  4. defer srv.Close()
  5. c := &PriceClient{Endpoint: srv.URL}
  6. price, err := c.GetPrice("1/1/2023")
  7. // 处理错误，检查返回值

以供参考，你还应该查看gomock，因为你将遇到的大多数其他模拟问题在语言中没有内置解决方案。

英文:

The idiomatic way to do HTTP testing with Go is using http/httptest (examples)

In your case, all you would need to do is make the base URL injectable:

  1. var APIEndpoint = "http://endpoint/"
  3. func getPrice(date string) (int, error) {
  4.   url := (fmt.Printf("%s/%s", APIEndpoint, date))
  5.   resp, err := http.Get(url)
  6.   // Unmarshall body and get price
  7.   return price, nil
  8. }

And then in each test:

  1. srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  2. 	// Write the expected response to the writer
  3. }))
  4. defer srv.Close()
  5. APIEndpoint = srv.URL
  6. price, err := getPrice("1/1/2023")
  7. // Handle error, check return

A slightly better design would be to wrap your API in a client struct and make getPrice a receiver method:

  1. type PriceClient struct {
  2.     Endpoint string
  3. }
  5. func (pc *PriceClient) GetPrice(date string) (int, error) {
  6.   url := (fmt.Printf("%s/%s", pc.Endpoint, date))
  7.   resp, err := http.Get(url)
  8.   // Unmarshall body and get price
  9.   return price, nil
  10. }
  1. srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
  2. 	// Write the expected response to the writer
  3. }))
  4. defer srv.Close()
  5. c := &PriceClient{Endpoint: srv.URL}
  6. price, err := c.GetPrice("1/1/2023")
  7. // Handle error, check return

For future reference, you should also have a look at gomock, since most other mocking problems you'll encounter do not have solutions built-in to the language.

答案2

得分: 1

你可以这样模拟getPrice函数：

在你的包中定义一个变量getPrice，并将其设置为你的函数。

  1. package server
  3. var getPrice = getPriceFn
  5. func getPriceFn(date string) {
  6.   url := fmt.Printf("http://endponint/%s", date)
  7.   resp, err := http.Get(url)
  8.   // 解析响应体并获取价格
  9.   return price
  10. }

在你的测试文件中给getPrice变量赋予一个模拟函数。

  1. package server
  3. func mockGetPrice(date string) (int, error) {
  4.   return 1, nil
  5. }
  7. func testSomething(t *testing.T) {
  8.   getPrice = mockGetPrice
  9.   // 做一些操作
  10. }

如果你想模拟http.Get以便测试getPrice函数，你可以使用httpmock包。

  1. import "github.com/jarcoal/httpmock"
  3. func TestGetPrice(date string) {
  4.   httpmock.Activate()
  5.   defer httpmock.DeactivateAndReset()
  6.   url := fmt.Printf("http://endponint/%s", date)
  7.   httpmock.RegisterResponder("GET", url,
  8.     httpmock.NewStringResponder(200, "foo"))
  9.   getPrice(date)
  10.   // 进行断言
  11. }
英文:

you can mock getPrice like so:

in your package define a variable getPrice and set it to your function.

  1. package server
  3. var getPrice = getPriceFn
  5. func getPriceFn(date string) {
  6.   url := (fmt.Printf("http://endponint/%s", date))
  7.     resp, err := http.Get(url)
  8.     // Unmarshall body and get price
  9.     return price
  10. }

in your test file give the getPrice variable a mock function.

  1. package server
  3. func mockGetPrice(date string) (int, error) {
  4.     return 1,nil
  5. }
  7. func testSomething(t *testing.T) {
  8.     getPrice = mockGetPrice
  9.     // do stuff
  10. }

if you want to mock http.get so you can test getPrice, then you can use the httpmock package.

  1. import "github.com/jarcoal/httpmock"
  3. func TestGetPrice(date string) {
  4.   httpmock.Activate()
  5.   defer httpmock.DeactivateAndReset()
  6.   url := (fmt.Printf("http://endponint/%s", date))
  7.   httpmock.RegisterResponder("GET", url,
  8.     httpmock.NewStringResponder(200, "foo"))
  9.   getPrice(date)
  10.   // make assertions
  11. }
  13. </details>

huangapple
  • 本文由 发表于 2023年5月19日 21:53:32
  • 转载请务必保留本文链接：https://go.coder-hub.com/76289762.html
  • go
  • testing
  • unit-testing
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