Golang 单元测试中的问题：简单错误。

huangapple
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英文:

Golang Issue with Unit Testing for simple error

问题

我正在尝试测试一个内部存在错误的函数，名为ResponseJson。该函数不返回错误，但会发送一个响应的 JSON。以下是该函数的代码：

  1. func ResponseJson(w http.ResponseWriter, Code int, Message string) {
  2. 	jsonStatus := struct {
  3. 		Code    int    `json:"code"`
  4. 		Message string `json:"message"`
  5. 	}{
  6. 		Message: Message,
  7. 		Code:    Code,
  8. 	}
  10. 	bs, err := json.Marshal(jsonStatus)
  12. 	if err != nil {
  13. 		log.Println("Error in Marshal JSON in ResponseJson:", err)
  14. 		str := "Internal Server Error. Please contact the System Administrator."
  15. 		io.WriteString(w, str)
  16. 		return
  17. 	} else {
  18. 		io.WriteString(w, string(bs))
  19. 		return
  20. 	}
  22. }

以下是我的单元测试代码，它创建了一个模拟的 ResponseWriter，并且能够成功测试没有错误的情况下的写入响应 JSON。由于 ResponseJson() 函数没有返回错误类型，我该如何在 Test_ResponseJson 函数中测试它呢？

  1. func Test_ResponseJson(t *testing.T) {
  2. 	responseJsonTests := []struct {
  3. 		testName             string
  4. 		code                 int
  5. 		message              string
  6. 		expectedJsonResponse string
  7. 	}{
  8. 		{"Successful Login", http.StatusOK, "Successfully Logged In!", `{"code":200,"message":"Successfully Logged In!"}`},
  9. 		{"Existing username", http.StatusBadRequest, "Username already exists. Please try again.", `{"code":400,"message":"Username already exists. Please try again."}`},
  10. 	}
  12. 	for _, e := range responseJsonTests {
  13. 		// 创建一个模拟的 ResponseWriter
  14. 		w := httptest.NewRecorder()
  16. 		ResponseJson(w, e.code, e.message)
  18. 		// 将响应体读取为字符串
  19. 		body, _ := io.ReadAll(w.Result().Body)
  20. 		actual := string(body)
  22. 		expected := e.expectedJsonResponse
  23. 		if actual != expected {
  24. 			t.Errorf("%s: expected %s but got %s", e.testName, e.expectedJsonResponse, actual)
  25. 		}
  26. 	}
  27. }

此外，我创建了一个函数，用于生成 log.Println() 内置函数的实际日志输出。我知道 log.Println() 函数是一个内置函数，很不可能出错。然而，我想在我的单元测试中实现100%的覆盖率。请帮忙！谢谢 Golang 单元测试中的问题：简单错误。

  1. func GenerateLogOutput(message string, errorMessage string) string {
  2. 	// 创建一个新的 bytes.Buffer 来捕获日志输出
  3. 	var buf bytes.Buffer
  5. 	// 将日志输出重定向到一个不同的目标，设置为缓冲区
  6. 	// 默认情况下，日志消息会被写入标准错误流 os.Stderr
  7. 	log.SetOutput(&buf)
  9. 	// 生成一个错误
  10. 	err := errors.New(errorMessage)
  12. 	w := httptest.NewRecorder()
  14. 	// 调用函数
  15. 	InternalServerError(w, message, err)
  16. 	actualOutput := buf.String()
  18. 	return actualOutput
  19. }

以上是你要翻译的内容。

英文:

I am having trouble trying to test this function with an error inside. The following is my ResponseJson function which does not return an error but sends a response json.

  1. func ResponseJson(w http.ResponseWriter, Code int, Message string) {
  2. 	jsonStatus := struct {
  3. 		Code int `json:"code"`
  4. 		Message string `json:"message"`
  5. 	}{
  6. 		Message: Message,
  7. 		Code: Code,
  8. 	}
  10. 	bs, err := json.Marshal(jsonStatus);
  12. 	if err != nil {
  13. 		log.Println("Error in Marshal JSON in ResponseJson: ", err)
  14. 		str := "Internal Server Error. Please contact the System Administrator."
  15. 		io.WriteString(w, str);
  16. 		return 
  17. 	} else {
  18. 		io.WriteString(w, string(bs));
  19. 		return
  20. 	}
  21. 	
  22. }

The following is my unit testing code which creates a mock ResponseWriter and it is able to successfully test the writer response json for cases with no errors. Since I am not returning an error type in ResponseJson() function, how do I test it inside the Test_ResponseJson function as shown below?

  1. func Test_ResponseJson(t *testing.T) {
  2. 	responseJsonTests := []struct {
  3. 		testName string
  4. 		code int
  5. 		message string
  6. 		expectedJsonResponse string
  7. 	} {
  8. 		{"Successful Login", http.StatusOK, "Successfully Logged In!", `{"code":200,"message":"Successfully Logged In!"}`},
  9. 		{"Existing username", http.StatusBadRequest, "Username already exists. Please try again.", `{"code":400,"message":"Username already exists. Please try again."}`},
  10. 	}
  12. 	for _, e := range responseJsonTests {
  13. 		// Creating a mock ResponseWriter
  14. 		w := httptest.NewRecorder()
  16. 		ResponseJson(w, e.code, e.message)
  18. 		// Read the response body as a string
  19. 		body, _ := io.ReadAll(w.Result().Body)
  20. 		actual := string(body)
  22. 		expected := e.expectedJsonResponse
  23. 		if actual != expected {
  24. 			t.Errorf("%s: expected %s but got %s", e.testName, e.expectedJsonResponse, actual)
  25. 		}
  26. 	}
  27. }

Also, I have created a function which generates an actual log output for log.Println() built-in function. I am aware that the log.Println() function is a built-in function and it is highly unlikely to fail. However, I want to achieve 100% coverage in my unit testing. Please help! Thank you Golang 单元测试中的问题：简单错误。

  1. func GenerateLogOutput(message string, errorMessage string) string {
  2. 	// Create a new bytes.Buffer to capture the log output
  3. 	var buf bytes.Buffer
  5. 	// Redirect log output to a different destination set as a buffer
  6. 	// By default, log message are written to the standard error stream os.Stderr
  7. 	log.SetOutput(&buf)
  9. 	// Generate an error
  10. 	err := errors.New(errorMessage)
  12. 	w := httptest.NewRecorder()
  14. 	// Calling the function
  15. 	InternalServerError(w, message, err)
  16. 	actualOutput := buf.String()
  18. 	return actualOutput
  19. }

答案1

得分: 1

简单来说，我们可以编写一个针对ResponseJson函数的测试用例，如下所示。

  1. func Test_ResponseJson(t *testing.T) {
  2. 	tests := []struct {
  3. 		Code        int
  4. 		Message     string
  5. 		ExpectedStr string
  6. 	}{
  7. 		{
  8. 			Code:        1,
  9. 			Message:     "sample message",
  10. 			ExpectedStr: `{"code":1,"message":"sample message"}`,
  11. 		},
  12. 	}
  13. 	for _, test := range tests {
  14. 		w := httptest.NewRecorder()
  16. 		ResponseJson(w, test.Code, test.Message)
  18. 		res := w.Result()
  19. 		data, err := ioutil.ReadAll(res.Body)
  20. 		res.Body.Close()
  22. 		actualStr := string(data)
  24. 		assert.Nil(t, err, "Invalid test data")
  25. 		assert.Equal(t, actualStr, test.ExpectedStr)
  26. 	}
  27. }

我们无法从bs, err := json.Marshal(jsonStatus)中获得错误。json.Marshal函数可以返回两种类型的错误。

  1. UnsupportedTypeError（例如：通道、复杂和函数值）
  2. UnsupportedValueError（例如：循环数据结构）

我们无法解析值以生成上述任何一种错误。我们正在解析具有支持的值和支持的类型的结构体。因此，我们无法编写具有100%覆盖率的测试。

英文:

Simply, We can write a test case for the ResponseJson function as below.

  1.  func Test_ResponseJson(t *testing.T) {
  2. 	tests := []struct {
  3. 		Code        int
  4. 		Message     string
  5. 		ExpectedStr string
  6. 	}{
  7. 		{
  8. 			Code:        1,
  9. 			Message:     "sample message",
  10. 			ExpectedStr: "{\"code\":1,\"message\":\"sample message\"}",
  11. 		},
  12. 	}
  13. 	for _, test := range tests {
  14. 		w := httptest.NewRecorder()
  16. 		ResponseJson(w, test.Code, test.Message)
  18. 		res := w.Result()
  19. 		data, err := ioutil.ReadAll(res.Body)
  20. 		res.Body.Close()
  22. 		actualStr := string(data)
  24. 		assert.Nil(t, err, "Invalid test data")
  25. 		assert.Equal(t, actualStr, test.ExpectedStr)
  26. 	}
  27. }

We cannot get an error from bs, err := json.Marshal(jsonStatus). The json.Marshal function can return two types of errors.

  1. UnsupportedTypeError (ex: channel, complex, and function values)
  2. UnsupportedValueError (ex: cyclic data structures)

We cannot parse values to generate either one of the above errors. We are parsing a struct with supported values and supported types. Therefore, we cannot write tests with 100% coverage.

huangapple
  • 本文由 发表于 2023年3月12日 10:02:01
  • 转载请务必保留本文链接：https://go.coder-hub.com/75710686.html
  • go
  • unit-testing
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