Move ErrorCode logic to new errcode package
Make HTTP status codes match the ErrorCode by looking it up in the Descriptors Signed-off-by: Doug Davis <dug@us.ibm.com>
This commit is contained in:
Doug Davis
parent
5f553b3cfc
commit
f565d6abb7
16 changed files with 444 additions and 405 deletions
206
docs/api/errcode/errors.go
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206
docs/api/errcode/errors.go
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package errcode
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import (
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"fmt"
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"net/http"
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"strings"
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)
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// ErrorCode represents the error type. The errors are serialized via strings
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// and the integer format may change and should *never* be exported.
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type ErrorCode int
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// ErrorDescriptor provides relevant information about a given error code.
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type ErrorDescriptor struct {
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// Code is the error code that this descriptor describes.
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Code ErrorCode
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// Value provides a unique, string key, often captilized with
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// underscores, to identify the error code. This value is used as the
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// keyed value when serializing api errors.
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Value string
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// Message is a short, human readable decription of the error condition
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// included in API responses.
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Message string
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// Description provides a complete account of the errors purpose, suitable
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// for use in documentation.
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Description string
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// HTTPStatusCode provides the http status code that is associated with
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// this error condition.
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HTTPStatusCode int
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}
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var (
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errorCodeToDescriptors = map[ErrorCode]ErrorDescriptor{}
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idToDescriptors = map[string]ErrorDescriptor{}
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)
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const (
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// ErrorCodeUnknown is a catch-all for errors not defined below.
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ErrorCodeUnknown ErrorCode = 10000 + iota
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)
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var errorDescriptors = []ErrorDescriptor{
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{
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Code: ErrorCodeUnknown,
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Value: "UNKNOWN",
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Message: "unknown error",
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Description: `Generic error returned when the error does not have an
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API classification.`,
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HTTPStatusCode: http.StatusInternalServerError,
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},
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}
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// LoadErrors will register a new set of Errors into the system
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func LoadErrors(errs *[]ErrorDescriptor) {
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for _, descriptor := range *errs {
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if _, ok := idToDescriptors[descriptor.Value]; ok {
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panic(fmt.Sprintf("ErrorValue %s is already registered", descriptor.Value))
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}
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if _, ok := errorCodeToDescriptors[descriptor.Code]; ok {
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panic(fmt.Sprintf("ErrorCode %d is already registered", descriptor.Code))
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}
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errorCodeToDescriptors[descriptor.Code] = descriptor
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idToDescriptors[descriptor.Value] = descriptor
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}
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}
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// ParseErrorCode attempts to parse the error code string, returning
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// ErrorCodeUnknown if the error is not known.
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func ParseErrorCode(s string) ErrorCode {
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desc, ok := idToDescriptors[s]
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if !ok {
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return ErrorCodeUnknown
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}
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return desc.Code
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}
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// Descriptor returns the descriptor for the error code.
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func (ec ErrorCode) Descriptor() ErrorDescriptor {
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d, ok := errorCodeToDescriptors[ec]
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if !ok {
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return ErrorCodeUnknown.Descriptor()
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}
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return d
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}
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// String returns the canonical identifier for this error code.
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func (ec ErrorCode) String() string {
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return ec.Descriptor().Value
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}
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// Message returned the human-readable error message for this error code.
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func (ec ErrorCode) Message() string {
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return ec.Descriptor().Message
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}
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// MarshalText encodes the receiver into UTF-8-encoded text and returns the
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// result.
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func (ec ErrorCode) MarshalText() (text []byte, err error) {
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return []byte(ec.String()), nil
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}
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// UnmarshalText decodes the form generated by MarshalText.
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func (ec *ErrorCode) UnmarshalText(text []byte) error {
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desc, ok := idToDescriptors[string(text)]
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if !ok {
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desc = ErrorCodeUnknown.Descriptor()
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}
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*ec = desc.Code
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return nil
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}
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// Error provides a wrapper around ErrorCode with extra Details provided.
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type Error struct {
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Code ErrorCode `json:"code"`
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Message string `json:"message,omitempty"`
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Detail interface{} `json:"detail,omitempty"`
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}
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// Error returns a human readable representation of the error.
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func (e Error) Error() string {
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return fmt.Sprintf("%s: %s",
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strings.ToLower(strings.Replace(e.Code.String(), "_", " ", -1)),
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e.Message)
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}
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// Errors provides the envelope for multiple errors and a few sugar methods
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// for use within the application.
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type Errors struct {
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Errors []Error `json:"errors,omitempty"`
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}
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// Push pushes an error on to the error stack, with the optional detail
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// argument. It is a programming error (ie panic) to push more than one
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// detail at a time.
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func (errs *Errors) Push(code ErrorCode, details ...interface{}) {
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if len(details) > 1 {
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panic("please specify zero or one detail items for this error")
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}
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var detail interface{}
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if len(details) > 0 {
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detail = details[0]
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}
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if err, ok := detail.(error); ok {
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detail = err.Error()
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}
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errs.PushErr(Error{
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Code: code,
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Message: code.Message(),
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Detail: detail,
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})
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}
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// PushErr pushes an error interface onto the error stack.
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func (errs *Errors) PushErr(err error) {
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switch err.(type) {
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case Error:
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errs.Errors = append(errs.Errors, err.(Error))
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default:
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errs.Errors = append(errs.Errors, Error{Message: err.Error()})
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}
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}
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func (errs *Errors) Error() string {
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switch errs.Len() {
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case 0:
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return "<nil>"
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case 1:
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return errs.Errors[0].Error()
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default:
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msg := "errors:\n"
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for _, err := range errs.Errors {
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msg += err.Error() + "\n"
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}
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return msg
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}
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}
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// Clear clears the errors.
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func (errs *Errors) Clear() {
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errs.Errors = nil
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}
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// Len returns the current number of errors.
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func (errs *Errors) Len() int {
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return len(errs.Errors)
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}
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// init loads the default errors that are part of the errcode package
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func init() {
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LoadErrors(&errorDescriptors)
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}
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167
docs/api/errcode/errors_test.go
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167
docs/api/errcode/errors_test.go
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@ -0,0 +1,167 @@
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package errcode
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import (
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"encoding/json"
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// "reflect"
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"testing"
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// "github.com/docker/distribution/digest"
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)
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// TestErrorCodes ensures that error code format, mappings and
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// marshaling/unmarshaling. round trips are stable.
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func TestErrorCodes(t *testing.T) {
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for _, desc := range errorDescriptors {
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if desc.Code.String() != desc.Value {
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t.Fatalf("error code string incorrect: %q != %q", desc.Code.String(), desc.Value)
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}
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if desc.Code.Message() != desc.Message {
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t.Fatalf("incorrect message for error code %v: %q != %q", desc.Code, desc.Code.Message(), desc.Message)
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}
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// Serialize the error code using the json library to ensure that we
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// get a string and it works round trip.
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p, err := json.Marshal(desc.Code)
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if err != nil {
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t.Fatalf("error marshaling error code %v: %v", desc.Code, err)
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}
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if len(p) <= 0 {
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t.Fatalf("expected content in marshaled before for error code %v", desc.Code)
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}
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// First, unmarshal to interface and ensure we have a string.
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var ecUnspecified interface{}
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if err := json.Unmarshal(p, &ecUnspecified); err != nil {
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t.Fatalf("error unmarshaling error code %v: %v", desc.Code, err)
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}
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if _, ok := ecUnspecified.(string); !ok {
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t.Fatalf("expected a string for error code %v on unmarshal got a %T", desc.Code, ecUnspecified)
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}
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// Now, unmarshal with the error code type and ensure they are equal
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var ecUnmarshaled ErrorCode
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if err := json.Unmarshal(p, &ecUnmarshaled); err != nil {
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t.Fatalf("error unmarshaling error code %v: %v", desc.Code, err)
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}
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if ecUnmarshaled != desc.Code {
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t.Fatalf("unexpected error code during error code marshal/unmarshal: %v != %v", ecUnmarshaled, desc.Code)
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}
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}
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}
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// TestErrorsManagement does a quick check of the Errors type to ensure that
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// members are properly pushed and marshaled.
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/*
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func TestErrorsManagement(t *testing.T) {
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var errs Errors
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errs.Push(ErrorCodeDigestInvalid)
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errs.Push(ErrorCodeBlobUnknown,
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map[string]digest.Digest{"digest": "sometestblobsumdoesntmatter"})
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p, err := json.Marshal(errs)
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if err != nil {
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t.Fatalf("error marashaling errors: %v", err)
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}
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expectedJSON := "{\"errors\":[{\"code\":\"DIGEST_INVALID\",\"message\":\"provided digest did not match uploaded content\"},{\"code\":\"BLOB_UNKNOWN\",\"message\":\"blob unknown to registry\",\"detail\":{\"digest\":\"sometestblobsumdoesntmatter\"}}]}"
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if string(p) != expectedJSON {
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t.Fatalf("unexpected json: %q != %q", string(p), expectedJSON)
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}
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errs.Clear()
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errs.Push(ErrorCodeUnknown)
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expectedJSON = "{\"errors\":[{\"code\":\"UNKNOWN\",\"message\":\"unknown error\"}]}"
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p, err = json.Marshal(errs)
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if err != nil {
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t.Fatalf("error marashaling errors: %v", err)
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}
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if string(p) != expectedJSON {
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t.Fatalf("unexpected json: %q != %q", string(p), expectedJSON)
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}
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}
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// TestMarshalUnmarshal ensures that api errors can round trip through json
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// without losing information.
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func TestMarshalUnmarshal(t *testing.T) {
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var errors Errors
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for _, testcase := range []struct {
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description string
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err Error
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}{
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{
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description: "unknown error",
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err: Error{
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Code: ErrorCodeUnknown,
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Message: ErrorCodeUnknown.Descriptor().Message,
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},
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},
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{
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description: "unknown manifest",
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err: Error{
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Code: ErrorCodeManifestUnknown,
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Message: ErrorCodeManifestUnknown.Descriptor().Message,
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},
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},
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{
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description: "unknown manifest",
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err: Error{
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Code: ErrorCodeBlobUnknown,
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Message: ErrorCodeBlobUnknown.Descriptor().Message,
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Detail: map[string]interface{}{"digest": "asdfqwerqwerqwerqwer"},
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},
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},
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} {
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fatalf := func(format string, args ...interface{}) {
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t.Fatalf(testcase.description+": "+format, args...)
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}
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unexpectedErr := func(err error) {
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fatalf("unexpected error: %v", err)
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}
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p, err := json.Marshal(testcase.err)
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if err != nil {
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unexpectedErr(err)
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}
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var unmarshaled Error
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if err := json.Unmarshal(p, &unmarshaled); err != nil {
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unexpectedErr(err)
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}
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if !reflect.DeepEqual(unmarshaled, testcase.err) {
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fatalf("errors not equal after round trip: %#v != %#v", unmarshaled, testcase.err)
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}
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// Roll everything up into an error response envelope.
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errors.PushErr(testcase.err)
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}
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p, err := json.Marshal(errors)
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if err != nil {
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t.Fatalf("unexpected error marshaling error envelope: %v", err)
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}
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var unmarshaled Errors
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if err := json.Unmarshal(p, &unmarshaled); err != nil {
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t.Fatalf("unexpected error unmarshaling error envelope: %v", err)
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}
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if !reflect.DeepEqual(unmarshaled, errors) {
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t.Fatalf("errors not equal after round trip: %#v != %#v", unmarshaled, errors)
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}
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}
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*/
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