测试在 Golang 函数中无法到达的执行路径。

huangapple
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英文:

test unreachable execution path within golang function

问题

我正在为下面的链码编写单元测试，以覆盖所有的执行路径。但是我没有找到一种方法来触发 JSON.Marshal 失败的情况。

我该如何传递一个能够通过 json.Unmarshal，但无法通过 json.Marshal 的值？

  1. func (c *MyContract) CreateAsset(ctx contractapi.TransactionContextInterface, values string) (bool, error) {
  2. 	
  3. 	doctype := "myAsset"
  4. 	txData := []byte(values)
  5. 	docData := new(DocData)
  6. 	docData.DataType = doctype
  8. 	// validate json input & map to struct
  9. 	err := json.Unmarshal(txData, &docData)
  10. 	if err != nil {
  11. 		return false, fmt.Errorf("failed docData unmarshalling: %s", err.Error())
  12. 	}
  14. 	docKey, _ := createKey(ctx, doctype, []string{docData.Key1, docData.Key2})
  16. 	exists, err := c.DocExists(ctx, docKey)
  17. 	if err != nil {
  18. 		return false, fmt.Errorf("could not read from world state %s", err)
  19. 	} else if exists {
  20. 		return false, fmt.Errorf("asset already exists")
  21. 	}
  23. 	txBytes, err := json.Marshal(docData)
  24. 	if err != nil {
  25. 		return false, fmt.Errorf("failed docData bytes marshalling: %s", err.Error())
  26. 	}
  28. 	return true, ctx.GetStub().PutState(docKey, txBytes)
  29. }

这是我当前的测试代码：

  1. func TestCreateAsset(t *testing.T) {
  2. 	var err error
  3. 	ctx, _ := setupStub()
  4. 	c := new(MyContract)
  7. 	_, err = c.CreateAsset(ctx, "{")
  8. 	assert.EqualError(t, err, "failed unmarshalling: unexpected end of JSON input", "testing malformed json")
  10. 	_, err = c.CreateAsset(ctx, "{\"key1\":\"mis\",\"key2\":\"sing\"}")
  11. 	assert.EqualError(t, err, "could not read from world state some failure")
  13. 	_, err = c.CreateAsset(ctx, "{\"key1\":\"001\",\"key2\":\"002\"}")
  14. 	assert.EqualError(t, err, "asset already exists")
  16. }
英文:

I'm writing unit-tests to cover all execution paths in the fabric chaincode below. But I don't see a way to reach the JSON.Marshall failing path.

How can I pass a value that passes to json.Unmarshal but it fails to json.Marshal?

  1. func (c *MyContract) CreateAsset(ctx contractapi.TransactionContextInterface, values string) (bool, error) {
  2. 	
  3. 	doctype := "myAsset"
  4. 	txData := []byte(values)
  5. 	docData := new(DocData)
  6. 	docData.DataType = doctype
  8. 	// validate json input & map to struct
  9. 	err := json.Unmarshal(txData, &docData)
  10. 	if err != nil {
  11. 		return false, fmt.Errorf("failed docData unmarshalling: %s", err.Error())
  12. 	}
  14. 	docKey, _ := createKey(ctx, doctype, []string{docData.Key1, docData.Key2})
  16. 	exists, err := c.DocExists(ctx, docKey)
  17. 	if err != nil {
  18. 		return false, fmt.Errorf("could not read from world state %s", err)
  19. 	} else if exists {
  20. 		return false, fmt.Errorf("asset already exists")
  21. 	}
  23. 	txBytes, err := json.Marshal(docData)
  24. 	if err != nil {
  25. 		return false, fmt.Errorf("failed docData bytes marshalling: %s", err.Error())
  26. 	}
  28. 	return true, ctx.GetStub().PutState(docKey, txBytes)
  29. }

This is my current test:

  1. func TestCreateAsset(t *testing.T) {
  2. 	var err error
  3. 	ctx, _ := setupStub()
  4. 	c := new(MyContract)
  7. 	_, err = c.CreateAsset(ctx, "{")
  8. 	assert.EqualError(t, err, "failed unmarshalling: unexpected end of JSON input", "testing malformed json")
  10. 	_, err = c.CreateAsset(ctx, "{\"key1\":\"mis\",\"key2\":\"sing\"}")
  11. 	assert.EqualError(t, err, "could not read from world state some failure")
  13. 	_, err = c.CreateAsset(ctx, "{\"key1\":\"001\",\"key2\":\"002\"}")
  14. 	assert.EqualError(t, err, "asset already exists")
  16. }

答案1

得分: 4

json.Marshal函数在无法对数据中的某个值进行编组时会失败。唯一引发失败的方法是在测试期间引入一个用于测试的字段，并在测试期间插入一个错误的值：

  1. type DocData struct {
  2.     ...
  3.     Test       interface{} `json:"test,omitempty"`
  4. }
  6. ...
  8. var induceFailure interface{}
  10. ...
  12. docData.Test = induceFailure
  13. txBytes, err := json.Marshal(docData)
  14. if err != nil {
  15.     return false, fmt.Errorf("failed docData bytes marshalling: %s", err.Error())
  16. }
  18. ...
  20. func TestMarshlFail(t *testing.T) {
  21.     induceFailure = make(chan struct{})
  22.     defer func() {
  23.        induceFailure = nil
  24.     }()
  25.     ...

可能不值得费力在那行代码上进行测试覆盖。

与问题无关，这里有一些改进你的代码的建议。

  • 包装错误而不是将错误转换为字符串：
  1. return nil, fmt.Errorf("failed docData unmarshalling: %w", err)
  • 因为docData是一个指针，在解组时不需要取值的地址。
  1. err := json.Unmarshal(txData, docData)
英文:

The json.Marshal function fails when a value in the data cannot be marshaled. The only way to induce a failure is to introduce a field for testing and slip in a bad value during a test:

  1. type DocData struct {
  2. 	…
  3. 	Test       interface{} `json:"test,omitempty"`
  4. }
  6. …
  8. var induceFailure interface{}
  10. …
  12. docData.Test = induceFailure
  13. txBytes, err := json.Marshal(docData)
  14. if err != nil {
  15.     return false, fmt.Errorf("failed docData bytes marshalling: %s", err.Error())
  16. }
  18. …
  20. func TestMarshlFail(t *testing.T) {
  21.     induceFailure = make(chan struct{})
  22.     defer func() {
  23.        induceFailure= nil
  24.     }()
  25.     …

It's probably not worth the hassle to get the test coverage on that line of code.

Unrelated to the question at hand, here are some improvements for your code.

  • Wrap errors instead of converting the errors to strings:

    1. return nil, fmt.Errorf("failed docData unmarshalling: %w", err)

  • Because docData is a pointer, there's no need to take the address of the value when unmarshaling.

    1. err := json.Unmarshal(txData, docData)

huangapple
  • 本文由 发表于 2021年11月5日 23:14:55
  • 转载请务必保留本文链接：https://go.coder-hub.com/69855468.html
  • go
  • hyperledger-chaincode
  • hyperledger-fabric
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