add MarshalJSON func for lib errs (#11614)

Customize the json output with message with err.Error(). Otherwise, the wrappged message will be lost
in the final errors object.

Signed-off-by: wang yan <wangyan@vmware.com>

src/lib/errors/errors.go

@@ -51,6 +51,17 @@ func (e *Error) StackTrace() string {
 	return e.Stack.frames().format()
 }
 
+// MarshalJSON ...
+func (e *Error) MarshalJSON() ([]byte, error) {
+	return json.Marshal(&struct {
+		Code    string `json:"code"`
+		Message string `json:"message"`
+	}{
+		Code:    e.Code,
+		Message: e.Error(),
+	})
+}
+
 // WithMessage ...
 func (e *Error) WithMessage(format string, v ...interface{}) *Error {
 	e.Message = fmt.Sprintf(format, v...)
@@ -86,7 +97,7 @@ func (errs Errors) Error() string {
 	for _, e := range errs {
 		err, ok := e.(*Error)
 		if !ok {
-			err = UnknownError(e).WithMessage(e.Error())
+			err = UnknownError(e)
 		}
 		if err.Code == "" {
 			err.Code = GeneralCode

src/lib/errors/errors_test.go

@@ -252,6 +252,28 @@ func (suite *ErrorTestSuite) TestCauseStd() {
 	suite.Equal(root, Cause(cause3))
 }
 
+func (suite *ErrorTestSuite) TestMarshalJSON() {
+	stdErr := errors.New("stdErr")
+	err := Wrap(stdErr, "root").WithCode(ConflictCode)
+	err2 := Wrap(err, "append message").WithCode(ConflictCode)
+
+	out, marErr := err2.MarshalJSON()
+	suite.Nil(marErr)
+	suite.Equal(`{"code":"CONFLICT","message":"append message: root: stdErr"}`, string(out))
+}
+
+func (suite *ErrorTestSuite) TestErrors() {
+	stdErr := errors.New("stdErr")
+	suite.Equal(`{"errors":[{"code":"UNKNOWN","message":"unknown: stdErr"}]}`, NewErrs(stdErr).Error())
+
+	err := Wrap(stdErr, "root").WithCode(ConflictCode)
+	err2 := Wrap(err, "append message").WithCode(ConflictCode)
+	suite.Equal(`{"errors":[{"code":"CONFLICT","message":"append message: root: stdErr"}]}`, NewErrs(err2).Error())
+
+	err = New(nil).WithCode(GeneralCode).WithMessage("internal server error")
+	suite.Equal(`{"errors":[{"code":"UNKNOWN","message":"internal server error"}]}`, NewErrs(err).Error())
+}
+
 func TestErrorTestSuite(t *testing.T) {
 	suite.Run(t, &ErrorTestSuite{})
 }

src/server/error/error_test.go

@@ -78,7 +78,7 @@ func TestAPIError(t *testing.T) {
 	e := pkg_errors.New("customized error")
 	statusCode, payload, stacktrace = apiError(e)
 	assert.Equal(t, http.StatusInternalServerError, statusCode)
-	assert.Equal(t, `{"errors":[{"code":"UNKNOWN","message":"customized error"}]}`, payload)
+	assert.Equal(t, `{"errors":[{"code":"UNKNOWN","message":"unknown: customized error"}]}`, payload)
 	assert.Contains(t, stacktrace, ``)
 
 }