vendor pkg/errors

parent 91dc8169
# Compiled Object files, Static and Dynamic libs (Shared Objects)
*.o
*.a
*.so
# Folders
_obj
_test
# Architecture specific extensions/prefixes
*.[568vq]
[568vq].out
*.cgo1.go
*.cgo2.c
_cgo_defun.c
_cgo_gotypes.go
_cgo_export.*
_testmain.go
*.exe
*.test
*.prof
language: go
go_import_path: github.com/pkg/errors
go:
- 1.4.x
- 1.5.x
- 1.6.x
- 1.7.x
- 1.8.x
- tip
script:
- go test -v ./...
Copyright (c) 2015, Dave Cheney <dave@cheney.net>
All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
* Redistributions of source code must retain the above copyright notice, this
list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the above copyright notice,
this list of conditions and the following disclaimer in the documentation
and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
# errors [![Travis-CI](https://travis-ci.org/pkg/errors.svg)](https://travis-ci.org/pkg/errors) [![AppVeyor](https://ci.appveyor.com/api/projects/status/b98mptawhudj53ep/branch/master?svg=true)](https://ci.appveyor.com/project/davecheney/errors/branch/master) [![GoDoc](https://godoc.org/github.com/pkg/errors?status.svg)](http://godoc.org/github.com/pkg/errors) [![Report card](https://goreportcard.com/badge/github.com/pkg/errors)](https://goreportcard.com/report/github.com/pkg/errors)
Package errors provides simple error handling primitives.
`go get github.com/pkg/errors`
The traditional error handling idiom in Go is roughly akin to
```go
if err != nil {
return err
}
```
which applied recursively up the call stack results in error reports without context or debugging information. The errors package allows programmers to add context to the failure path in their code in a way that does not destroy the original value of the error.
## Adding context to an error
The errors.Wrap function returns a new error that adds context to the original error. For example
```go
_, err := ioutil.ReadAll(r)
if err != nil {
return errors.Wrap(err, "read failed")
}
```
## Retrieving the cause of an error
Using `errors.Wrap` constructs a stack of errors, adding context to the preceding error. Depending on the nature of the error it may be necessary to reverse the operation of errors.Wrap to retrieve the original error for inspection. Any error value which implements this interface can be inspected by `errors.Cause`.
```go
type causer interface {
Cause() error
}
```
`errors.Cause` will recursively retrieve the topmost error which does not implement `causer`, which is assumed to be the original cause. For example:
```go
switch err := errors.Cause(err).(type) {
case *MyError:
// handle specifically
default:
// unknown error
}
```
[Read the package documentation for more information](https://godoc.org/github.com/pkg/errors).
## Contributing
We welcome pull requests, bug fixes and issue reports. With that said, the bar for adding new symbols to this package is intentionally set high.
Before proposing a change, please discuss your change by raising an issue.
## Licence
BSD-2-Clause
version: build-{build}.{branch}
clone_folder: C:\gopath\src\github.com\pkg\errors
shallow_clone: true # for startup speed
environment:
GOPATH: C:\gopath
platform:
- x64
# http://www.appveyor.com/docs/installed-software
install:
# some helpful output for debugging builds
- go version
- go env
# pre-installed MinGW at C:\MinGW is 32bit only
# but MSYS2 at C:\msys64 has mingw64
- set PATH=C:\msys64\mingw64\bin;%PATH%
- gcc --version
- g++ --version
build_script:
- go install -v ./...
test_script:
- set PATH=C:\gopath\bin;%PATH%
- go test -v ./...
#artifacts:
# - path: '%GOPATH%\bin\*.exe'
deploy: off
// +build go1.7
package errors
import (
"fmt"
"testing"
stderrors "errors"
)
func noErrors(at, depth int) error {
if at >= depth {
return stderrors.New("no error")
}
return noErrors(at+1, depth)
}
func yesErrors(at, depth int) error {
if at >= depth {
return New("ye error")
}
return yesErrors(at+1, depth)
}
// GlobalE is an exported global to store the result of benchmark results,
// preventing the compiler from optimising the benchmark functions away.
var GlobalE error
func BenchmarkErrors(b *testing.B) {
type run struct {
stack int
std bool
}
runs := []run{
{10, false},
{10, true},
{100, false},
{100, true},
{1000, false},
{1000, true},
}
for _, r := range runs {
part := "pkg/errors"
if r.std {
part = "errors"
}
name := fmt.Sprintf("%s-stack-%d", part, r.stack)
b.Run(name, func(b *testing.B) {
var err error
f := yesErrors
if r.std {
f = noErrors
}
b.ReportAllocs()
for i := 0; i < b.N; i++ {
err = f(0, r.stack)
}
b.StopTimer()
GlobalE = err
})
}
}
// Package errors provides simple error handling primitives.
//
// The traditional error handling idiom in Go is roughly akin to
//
// if err != nil {
// return err
// }
//
// which applied recursively up the call stack results in error reports
// without context or debugging information. The errors package allows
// programmers to add context to the failure path in their code in a way
// that does not destroy the original value of the error.
//
// Adding context to an error
//
// The errors.Wrap function returns a new error that adds context to the
// original error by recording a stack trace at the point Wrap is called,
// and the supplied message. For example
//
// _, err := ioutil.ReadAll(r)
// if err != nil {
// return errors.Wrap(err, "read failed")
// }
//
// If additional control is required the errors.WithStack and errors.WithMessage
// functions destructure errors.Wrap into its component operations of annotating
// an error with a stack trace and an a message, respectively.
//
// Retrieving the cause of an error
//
// Using errors.Wrap constructs a stack of errors, adding context to the
// preceding error. Depending on the nature of the error it may be necessary
// to reverse the operation of errors.Wrap to retrieve the original error
// for inspection. Any error value which implements this interface
//
// type causer interface {
// Cause() error
// }
//
// can be inspected by errors.Cause. errors.Cause will recursively retrieve
// the topmost error which does not implement causer, which is assumed to be
// the original cause. For example:
//
// switch err := errors.Cause(err).(type) {
// case *MyError:
// // handle specifically
// default:
// // unknown error
// }
//
// causer interface is not exported by this package, but is considered a part
// of stable public API.
//
// Formatted printing of errors
//
// All error values returned from this package implement fmt.Formatter and can
// be formatted by the fmt package. The following verbs are supported
//
// %s print the error. If the error has a Cause it will be
// printed recursively
// %v see %s
// %+v extended format. Each Frame of the error's StackTrace will
// be printed in detail.
//
// Retrieving the stack trace of an error or wrapper
//
// New, Errorf, Wrap, and Wrapf record a stack trace at the point they are
// invoked. This information can be retrieved with the following interface.
//
// type stackTracer interface {
// StackTrace() errors.StackTrace
// }
//
// Where errors.StackTrace is defined as
//
// type StackTrace []Frame
//
// The Frame type represents a call site in the stack trace. Frame supports
// the fmt.Formatter interface that can be used for printing information about
// the stack trace of this error. For example:
//
// if err, ok := err.(stackTracer); ok {
// for _, f := range err.StackTrace() {
// fmt.Printf("%+s:%d", f)
// }
// }
//
// stackTracer interface is not exported by this package, but is considered a part
// of stable public API.
//
// See the documentation for Frame.Format for more details.
package errors
import (
"fmt"
"io"
)
// New returns an error with the supplied message.
// New also records the stack trace at the point it was called.
func New(message string) error {
return &fundamental{
msg: message,
stack: callers(),
}
}
// Errorf formats according to a format specifier and returns the string
// as a value that satisfies error.
// Errorf also records the stack trace at the point it was called.
func Errorf(format string, args ...interface{}) error {
return &fundamental{
msg: fmt.Sprintf(format, args...),
stack: callers(),
}
}
// fundamental is an error that has a message and a stack, but no caller.
type fundamental struct {
msg string
*stack
}
func (f *fundamental) Error() string { return f.msg }
func (f *fundamental) Format(s fmt.State, verb rune) {
switch verb {
case 'v':
if s.Flag('+') {
io.WriteString(s, f.msg)
f.stack.Format(s, verb)
return
}
fallthrough
case 's':
io.WriteString(s, f.msg)
case 'q':
fmt.Fprintf(s, "%q", f.msg)
}
}
// WithStack annotates err with a stack trace at the point WithStack was called.
// If err is nil, WithStack returns nil.
func WithStack(err error) error {
if err == nil {
return nil
}
return &withStack{
err,
callers(),
}
}
type withStack struct {
error
*stack
}
func (w *withStack) Cause() error { return w.error }
func (w *withStack) Format(s fmt.State, verb rune) {
switch verb {
case 'v':
if s.Flag('+') {
fmt.Fprintf(s, "%+v", w.Cause())
w.stack.Format(s, verb)
return
}
fallthrough
case 's':
io.WriteString(s, w.Error())
case 'q':
fmt.Fprintf(s, "%q", w.Error())
}
}
// Wrap returns an error annotating err with a stack trace
// at the point Wrap is called, and the supplied message.
// If err is nil, Wrap returns nil.
func Wrap(err error, message string) error {
if err == nil {
return nil
}
err = &withMessage{
cause: err,
msg: message,
}
return &withStack{
err,
callers(),
}
}
// Wrapf returns an error annotating err with a stack trace
// at the point Wrapf is call, and the format specifier.
// If err is nil, Wrapf returns nil.
func Wrapf(err error, format string, args ...interface{}) error {
if err == nil {
return nil
}
err = &withMessage{
cause: err,
msg: fmt.Sprintf(format, args...),
}
return &withStack{
err,
callers(),
}
}
// WithMessage annotates err with a new message.
// If err is nil, WithMessage returns nil.
func WithMessage(err error, message string) error {
if err == nil {
return nil
}
return &withMessage{
cause: err,
msg: message,
}
}
type withMessage struct {
cause error
msg string
}
func (w *withMessage) Error() string { return w.msg + ": " + w.cause.Error() }
func (w *withMessage) Cause() error { return w.cause }
func (w *withMessage) Format(s fmt.State, verb rune) {
switch verb {
case 'v':
if s.Flag('+') {
fmt.Fprintf(s, "%+v\n", w.Cause())
io.WriteString(s, w.msg)
return
}
fallthrough
case 's', 'q':
io.WriteString(s, w.Error())
}
}
// Cause returns the underlying cause of the error, if possible.
// An error value has a cause if it implements the following
// interface:
//
// type causer interface {
// Cause() error
// }
//
// If the error does not implement Cause, the original error will
// be returned. If the error is nil, nil will be returned without further
// investigation.
func Cause(err error) error {
type causer interface {
Cause() error
}
for err != nil {
cause, ok := err.(causer)
if !ok {
break
}
err = cause.Cause()
}
return err
}
package errors
import (
"errors"
"fmt"
"io"
"reflect"
"testing"
)
func TestNew(t *testing.T) {
tests := []struct {
err string
want error
}{
{"", fmt.Errorf("")},
{"foo", fmt.Errorf("foo")},
{"foo", New("foo")},
{"string with format specifiers: %v", errors.New("string with format specifiers: %v")},
}
for _, tt := range tests {
got := New(tt.err)
if got.Error() != tt.want.Error() {
t.Errorf("New.Error(): got: %q, want %q", got, tt.want)
}
}
}
func TestWrapNil(t *testing.T) {
got := Wrap(nil, "no error")
if got != nil {
t.Errorf("Wrap(nil, \"no error\"): got %#v, expected nil", got)
}
}
func TestWrap(t *testing.T) {
tests := []struct {
err error
message string
want string
}{
{io.EOF, "read error", "read error: EOF"},
{Wrap(io.EOF, "read error"), "client error", "client error: read error: EOF"},
}
for _, tt := range tests {
got := Wrap(tt.err, tt.message).Error()
if got != tt.want {
t.Errorf("Wrap(%v, %q): got: %v, want %v", tt.err, tt.message, got, tt.want)
}
}
}
type nilError struct{}
func (nilError) Error() string { return "nil error" }
func TestCause(t *testing.T) {
x := New("error")
tests := []struct {
err error
want error
}{{
// nil error is nil
err: nil,
want: nil,
}, {
// explicit nil error is nil
err: (error)(nil),
want: nil,
}, {
// typed nil is nil
err: (*nilError)(nil),
want: (*nilError)(nil),
}, {
// uncaused error is unaffected
err: io.EOF,
want: io.EOF,
}, {
// caused error returns cause
err: Wrap(io.EOF, "ignored"),
want: io.EOF,
}, {
err: x, // return from errors.New
want: x,
}, {
WithMessage(nil, "whoops"),
nil,
}, {
WithMessage(io.EOF, "whoops"),
io.EOF,
}, {
WithStack(nil),
nil,
}, {
WithStack(io.EOF),
io.EOF,
}}
for i, tt := range tests {
got := Cause(tt.err)
if !reflect.DeepEqual(got, tt.want) {
t.Errorf("test %d: got %#v, want %#v", i+1, got, tt.want)
}
}
}
func TestWrapfNil(t *testing.T) {
got := Wrapf(nil, "no error")
if got != nil {
t.Errorf("Wrapf(nil, \"no error\"): got %#v, expected nil", got)
}
}
func TestWrapf(t *testing.T) {
tests := []struct {
err error
message string
want string
}{
{io.EOF, "read error", "read error: EOF"},
{Wrapf(io.EOF, "read error without format specifiers"), "client error", "client error: read error without format specifiers: EOF"},
{Wrapf(io.EOF, "read error with %d format specifier", 1), "client error", "client error: read error with 1 format specifier: EOF"},
}
for _, tt := range tests {
got := Wrapf(tt.err, tt.message).Error()
if got != tt.want {
t.Errorf("Wrapf(%v, %q): got: %v, want %v", tt.err, tt.message, got, tt.want)
}
}
}
func TestErrorf(t *testing.T) {
tests := []struct {
err error
want string
}{
{Errorf("read error without format specifiers"), "read error without format specifiers"},
{Errorf("read error with %d format specifier", 1), "read error with 1 format specifier"},
}
for _, tt := range tests {
got := tt.err.Error()
if got != tt.want {
t.Errorf("Errorf(%v): got: %q, want %q", tt.err, got, tt.want)
}
}
}
func TestWithStackNil(t *testing.T) {
got := WithStack(nil)
if got != nil {
t.Errorf("WithStack(nil): got %#v, expected nil", got)
}
}
func TestWithStack(t *testing.T) {
tests := []struct {
err error
want string
}{
{io.EOF, "EOF"},
{WithStack(io.EOF), "EOF"},
}
for _, tt := range tests {
got := WithStack(tt.err).Error()
if got != tt.want {
t.Errorf("WithStack(%v): got: %v, want %v", tt.err, got, tt.want)
}
}
}
func TestWithMessageNil(t *testing.T) {
got := WithMessage(nil, "no error")
if got != nil {
t.Errorf("WithMessage(nil, \"no error\"): got %#v, expected nil", got)
}
}
func TestWithMessage(t *testing.T) {
tests := []struct {
err error
message string
want string
}{
{io.EOF, "read error", "read error: EOF"},
{WithMessage(io.EOF, "read error"), "client error", "client error: read error: EOF"},
}
for _, tt := range tests {
got := WithMessage(tt.err, tt.message).Error()
if got != tt.want {
t.Errorf("WithMessage(%v, %q): got: %q, want %q", tt.err, tt.message, got, tt.want)
}
}
}
// errors.New, etc values are not expected to be compared by value
// but the change in errors#27 made them incomparable. Assert that
// various kinds of errors have a functional equality operator, even
// if the result of that equality is always false.
func TestErrorEquality(t *testing.T) {
vals := []error{
nil,
io.EOF,
errors.New("EOF"),
New("EOF"),
Errorf("EOF"),
Wrap(io.EOF, "EOF"),
Wrapf(io.EOF, "EOF%d", 2),
WithMessage(nil, "whoops"),
WithMessage(io.EOF, "whoops"),
WithStack(io.EOF),
WithStack(nil),
}
for i := range vals {
for j := range vals {
_ = vals[i] == vals[j] // mustn't panic
}
}
}
package errors_test
import (
"fmt"
"github.com/pkg/errors"
)
func ExampleNew() {
err := errors.New("whoops")
fmt.Println(err)
// Output: whoops
}
func ExampleNew_printf() {
err := errors.New("whoops")
fmt.Printf("%+v", err)