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errors
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# 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

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Copyright (c) 2015, Dave Cheney <dave@cheney.net>
All rights reserved.
Modifications of the code made by by Friends of Go
Copyright (c) 2019, Friends of Go <contact@friendsofgo.tech>
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.

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# general
WORKDIR = $(PWD)
# coverage
COVERAGE_REPORT = coverage.txt
COVERAGE_PROFILE = profile.out
COVERAGE_MODE = atomic
coverage:
@cd $(WORKDIR); \
echo "" > $(COVERAGE_REPORT); \
for dir in `find . -name "*.go" | grep -o '.*/' | sort | uniq`; do \
go test -v -race $$dir -coverprofile=$(COVERAGE_PROFILE) -covermode=$(COVERAGE_MODE); \
if [ $$? != 0 ]; then \
exit 2; \
fi; \
if [ -f $(COVERAGE_PROFILE) ]; then \
cat $(COVERAGE_PROFILE) >> $(COVERAGE_REPORT); \
rm $(COVERAGE_PROFILE); \
fi; \
done; \

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[![FriendsOfGo](https://img.shields.io/badge/powered%20by-Friends%20of%20Go-73D7E2.svg)](https://friendsofgo.tech)
[![CircleCI](https://circleci.com/gh/friendsofgo/errors.svg?style=svg)](https://circleci.com/gh/friendsofgo/errors)
[![Build status](https://ci.appveyor.com/api/projects/status/phjkr6de4mnb19kq?svg=true)](https://ci.appveyor.com/project/aperezg/errors)
[![Version](https://img.shields.io/github/release/friendsofgo/errors.svg?style=flat-square)](https://github.com/friendsofgo/errors/releases/latest)
[![Go Report Card](https://goreportcard.com/badge/github.com/friendsofgo/errors)](https://goreportcard.com/report/github.com/friendsofgo/errors)
[![GoDoc](https://godoc.org/github.com/friendsofgo/errors?status.svg)](https://godoc.org/github.com/friendsofgo/errors)
# errors
This package is a fork from [github.com/pkg/errors](https://github.com/pkg/errors) package created by
[Dave Cheney](https://github.com/davecheney). The original package has no longer accepting proposals for new functionality.
With the new errors on [go 1.13](https://godoc.org/errors), the way to using the errors on Go has some
changes that can be applied into Dave Cheney library. We want to offer one way to migrate your code to new
errors, but with the minimum refactor, for that we've created this package.
This package provide the same interface that the original library have, but using new [go 1.13](https://godoc.org/errors)
errors, or in previous version [golang.org/x/xerrors](https://golang.org/x/xerrors) package.
## How to start using friendsofgo/errors
If you previously was using the package [github.com/pkg/errors](https://github.com/pkg/errors), you only need
change your imports for **github.com/friendsofgo/errors**, with this simple change now you're capable to use
[go 1.13](https://godoc.org/errors) in your code, and use the new methods `As` and `Is` if you want.
Furthermore the method `Wrap` `Wrapf become compatible with `Unwrap` interface of new [go 1.13](https://godoc.org/errors) errors.
## Adding context to an error
With the original package [go 1.13](https://godoc.org/errors) if you want add context, ergo wrap your error you need to create
a new error and using the new verb `"%w" like that:
```go
_, err := ioutil.ReadAll(r)
if err != nil {
return fmt.Errorf("read failed: %w", err)
}
```
Using our library you can do that forgetting to the new verb:
```go
_, err := ioutil.ReadAll(r)
if err != nil {
return errors.Wrap(err, "read failed")
}
```
## Retrieving the cause of an error
We want to keep the compatibility with the [github.com/pkg/errors](https://github.com/pkg/errors) package, for that
our package provides a `Cause` method, but this method is not longer needed, because we can use the new methods `Is` or `As`
that provides the official package.
So previously if you needed to check an error cause, your error must be implemented the `causer` inteface:
```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
}
```
But now you can do:
```go
var target *MyError
if errors.As(err, &target) {
// handle specifically
} else {
// unknown error
}
```
Or if you uses a sentinel error:
```go
var ErrMyError = errors.New("my sentinel error")
if errors.Is(err, ErrMyError) {
// handle specifically
} else {
// unknown error
}
```
## Disclaimer
This package was created to using with go 1.13 version however if you uses this package with a previous version, the methods
`As`, `Is`, `Wrap` and `Wrapf` will be using [golang.org/x/xerrors](https://golang.org/x/xerrors) package.
## Contributing
[Contributions](https://github.com/friendsofgo/errors/issues?q=is%3Aissue+is%3Aopen) are more than welcome, if you are interested please fork this repo and send your Pull Request.

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version: build-{build}.{branch}
clone_folder: C:\gopath\src\github.com\friendsofgo\errors
shallow_clone: true # for startup speed
environment:
GOPATH: C:\gopath
GO111MODULE: on
stack: go 1.13
platform:
- x64
# http://www.appveyor.com/docs/installed-software
install:
- go version
- go env
- set PATH=C:\msys64\mingw64\bin;%GOPATH%\bin;c:\go\bin;%PATH%
- go mod tidy
- 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

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// +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 interface{}
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 := "friendsofgo/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
})
}
}
func BenchmarkStackFormatting(b *testing.B) {
type run struct {
stack int
format string
}
runs := []run{
{10, "%s"},
{10, "%v"},
{10, "%+v"},
{30, "%s"},
{30, "%v"},
{30, "%+v"},
{60, "%s"},
{60, "%v"},
{60, "%+v"},
}
var stackStr string
for _, r := range runs {
name := fmt.Sprintf("%s-stack-%d", r.format, r.stack)
b.Run(name, func(b *testing.B) {
err := yesErrors(0, r.stack)
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
stackStr = fmt.Sprintf(r.format, err)
}
b.StopTimer()
})
}
for _, r := range runs {
name := fmt.Sprintf("%s-stacktrace-%d", r.format, r.stack)
b.Run(name, func(b *testing.B) {
err := yesErrors(0, r.stack)
st := err.(*fundamental).stack.StackTrace()
b.ReportAllocs()
b.ResetTimer()
for i := 0; i < b.N; i++ {
stackStr = fmt.Sprintf(r.format, st)
}
b.StopTimer()
})
}
GlobalE = stackStr
}

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package errors
// Original package created by Dave Cheney
// Copyright (c) 2015, Dave Cheney <dave@cheney.net>
//
// Modifications of the original package by Friends of Go
// Copyright (c) 2019, Friends of Go <contact@friendsofgo.tech>
//
// Package errors provides simple error handling primitives.
//
// The traditional error handling idiom in Go is roughly akin to
//
// if err != nil {
// return err
// }
//
// which when 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,
// together with 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: annotating an error with a stack trace and with 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 that 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
// }
//
// Although the causer interface is not exported by this package, it is
// considered a part of its stable public interface.
//
// With the new standard package error we have two new ways to figure what is the cause of
// our error:
//
// var target *MyError
// if errors.As(err, &target) {
// // handle specifically
// } else {
// // unknown error
// }
//
// or even with sentinel errors:
//
// var ErrMyError = errors.New("my sentinel error")
// if errors.Is(err, ErrMyError) {
// // handle specifically
// } else {
// // unknown error
// }
//
// 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
// }
//
// The returned errors.StackTrace type 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\n", f, f)
// }
// }
//
// Although the stackTracer interface is not exported by this package, it is
// considered a part of its stable public interface.
//
// See the documentation for Frame.Format for more details.
import (
"errors"
"fmt"
"io"
"strings"
)
// 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
}
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) Unwrap() 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
}
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 called, 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(),
}
}
// Is reports whether any error in err's chain matches target.
//
// The chain consists of err itself followed by the sequence of errors obtained by
// repeatedly calling Unwrap.
//
// An error is considered to match a target if it is equal to that target or if
// it implements a method Is(error) bool such that Is(target) returns true.
func Is(err error, target error) bool {
return errors.Is(err, target)
}
// As finds the first error in err's chain that matches target, and if so, sets
// target to that error value and returns true.
//
// The chain consists of err itself followed by the sequence of errors obtained by
// repeatedly calling Unwrap.
//
// An error matches target if the error's concrete value is assignable to the value
// pointed to by target, or if the error has a method As(interface{}) bool such that
// As(target) returns true. In the latter case, the As method is responsible for
// setting target.
//
// As will panic if target is not a non-nil pointer to either a type that implements
// error, or to any interface type. As returns false if err is nil.
func As(err error, target interface{}) bool {
return errors.As(err, target)
}
// 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,
}
}
// WithMessagef annotates err with the format specifier.
// If err is nil, WithMessagef returns nil.
func WithMessagef(err error, format string, args ...interface{}) error {
if err == nil {
return nil
}
return &withMessage{
cause: err,
msg: fmt.Sprintf(format, args...),
}
}
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) Unwrap() 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
}
if s.Flag('-') {
fmt.Fprintf(s, "%-v ; ", 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 {
var c causer
if !As(err, &c) {
break
}
err = c.Cause()
}
return err
}
func FormatPanicDebugStack(msg string) string {
msg = strings.ReplaceAll(msg, "\n", " < ")
msg = strings.ReplaceAll(msg, ") <", ") at")
idx := strings.Index(msg, "panic.go:")
if idx != -1 {
msg = msg[idx:]
}
if len(msg) > 2000 {
msg = msg[:2000] + "..."
}
return msg
}

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package errors
import (
"errors"
stdlib_errors "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)
}
}
}
func TestWithMessagefNil(t *testing.T) {
got := WithMessagef(nil, "no error")
if got != nil {
t.Errorf("WithMessage(nil, \"no error\"): got %#v, expected nil", got)
}
}
func TestWithMessagef(t *testing.T) {
tests := []struct {
err error
message string
want string
}{
{io.EOF, "read error", "read error: EOF"},
{WithMessagef(io.EOF, "read error without format specifier"), "client error", "client error: read error without format specifier: EOF"},
{WithMessagef(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 := WithMessagef(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
}
}
}
func TestIs(t *testing.T) {
sentinelError := stdlib_errors.New("sentinel error")
wrap := Wrap(sentinelError, "wrap error")
if !Is(wrap, sentinelError) {
t.Errorf("Expected that '%v' error and the '%v' error should be of the same type", sentinelError, wrap)
}
}
func TestAs(t *testing.T) {
type myError struct {
error
}
err := &myError{stdlib_errors.New("error")}
wrap := Wrap(err, "wrap error")
var tt *myError
if !As(wrap, &tt) {
t.Errorf("Expected that '%v' error and the '%v' error should be of the same type", err, wrap)
}
}

205
example_test.go Normal file
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@ -0,0 +1,205 @@
package errors_test
import (
"fmt"
"git.bit5.ru/backend/errors"
)
func ExampleNew() {
err := errors.New("whoops")
fmt.Println(err)
// Output: whoops
}
func ExampleNew_printf() {
err := errors.New("whoops")
fmt.Printf("%+v", err)
// Example output:
// whoops
// github.com/friendsofgo/errors_test.ExampleNew_printf
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:17
// testing.runExample
// /home/dfc/go/src/testing/example.go:114
// testing.RunExamples
// /home/dfc/go/src/testing/example.go:38
// testing.(*M).Run
// /home/dfc/go/src/testing/testing.go:744
// main.main
// /github.com/friendsofgo/errors/_test/_testmain.go:106
// runtime.main
// /home/dfc/go/src/runtime/proc.go:183
// runtime.goexit
// /home/dfc/go/src/runtime/asm_amd64.s:2059
}
func ExampleWithMessage() {
cause := errors.New("whoops")
err := errors.WithMessage(cause, "oh noes")
fmt.Println(err)
// Output: oh noes: whoops
}
func ExampleWithStack() {
cause := errors.New("whoops")
err := errors.WithStack(cause)
fmt.Println(err)
// Output: whoops
}
func ExampleWithStack_printf() {
cause := errors.New("whoops")
err := errors.WithStack(cause)
fmt.Printf("%+v", err)
// Example Output:
// whoops
// github.com/friendsofgo/errors_test.ExampleWithStack_printf
// /home/fabstu/go/src/github.com/friendsofgo/errors/example_test.go:55
// testing.runExample
// /usr/lib/go/src/testing/example.go:114
// testing.RunExamples
// /usr/lib/go/src/testing/example.go:38
// testing.(*M).Run
// /usr/lib/go/src/testing/testing.go:744
// main.main
// github.com/friendsofgo/errors/_test/_testmain.go:106
// runtime.main
// /usr/lib/go/src/runtime/proc.go:183
// runtime.goexit
// /usr/lib/go/src/runtime/asm_amd64.s:2086
// github.com/friendsofgo/errors_test.ExampleWithStack_printf
// /home/fabstu/go/src/github.com/friendsofgo/errors/example_test.go:56
// testing.runExample
// /usr/lib/go/src/testing/example.go:114
// testing.RunExamples
// /usr/lib/go/src/testing/example.go:38
// testing.(*M).Run
// /usr/lib/go/src/testing/testing.go:744
// main.main
// github.com/friendsofgo/errors/_test/_testmain.go:106
// runtime.main
// /usr/lib/go/src/runtime/proc.go:183
// runtime.goexit
// /usr/lib/go/src/runtime/asm_amd64.s:2086
}
func ExampleWrap() {
cause := errors.New("whoops")
err := errors.Wrap(cause, "oh noes")
fmt.Println(err)
// Output: oh noes: whoops
}
func fn() error {
e1 := errors.New("error")
e2 := errors.Wrap(e1, "inner")
e3 := errors.Wrap(e2, "middle")
return errors.Wrap(e3, "outer")
}
func ExampleCause() {
err := fn()
fmt.Println(err)
fmt.Println(errors.Cause(err))
// Output: outer: middle: inner: error
// error
}
func ExampleWrap_extended() {
err := fn()
fmt.Printf("%+v\n", err)
// Example output:
// error
// github.com/friendsofgo/errors_test.fn
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:47
// github.com/friendsofgo/errors_test.ExampleCause_printf
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:63
// testing.runExample
// /home/dfc/go/src/testing/example.go:114
// testing.RunExamples
// /home/dfc/go/src/testing/example.go:38
// testing.(*M).Run
// /home/dfc/go/src/testing/testing.go:744
// main.main
// /github.com/friendsofgo/errors/_test/_testmain.go:104
// runtime.main
// /home/dfc/go/src/runtime/proc.go:183
// runtime.goexit
// /home/dfc/go/src/runtime/asm_amd64.s:2059
// github.com/friendsofgo/errors_test.fn
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:48: inner
// github.com/friendsofgo/errors_test.fn
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:49: middle
// github.com/friendsofgo/errors_test.fn
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:50: outer
}
func ExampleWrapf() {
cause := errors.New("whoops")
err := errors.Wrapf(cause, "oh noes #%d", 2)
fmt.Println(err)
// Output: oh noes #2: whoops
}
func ExampleErrorf_extended() {
err := errors.Errorf("whoops: %s", "foo")
fmt.Printf("%+v", err)
// Example output:
// whoops: foo
// github.com/friendsofgo/errors_test.ExampleErrorf
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:101
// testing.runExample
// /home/dfc/go/src/testing/example.go:114
// testing.RunExamples
// /home/dfc/go/src/testing/example.go:38
// testing.(*M).Run
// /home/dfc/go/src/testing/testing.go:744
// main.main
// /github.com/friendsofgo/errors/_test/_testmain.go:102
// runtime.main
// /home/dfc/go/src/runtime/proc.go:183
// runtime.goexit
// /home/dfc/go/src/runtime/asm_amd64.s:2059
}
func Example_stackTrace() {
type stackTracer interface {
StackTrace() errors.StackTrace
}
err, ok := errors.Cause(fn()).(stackTracer)
if !ok {
panic("oops, err does not implement stackTracer")
}
st := err.StackTrace()
fmt.Printf("%+v", st[0:2]) // top two frames
// Example output:
// github.com/friendsofgo/errors_test.fn
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:47
// github.com/friendsofgo/errors_test.Example_stackTrace
// /home/dfc/src/github.com/friendsofgo/errors/example_test.go:127
}
func ExampleCause_printf() {
err := errors.Wrap(func() error {
return func() error {
return errors.Errorf("hello %s", fmt.Sprintf("world"))
}()
}(), "failed")
fmt.Printf("%v", err)
// Output: failed: hello world
}

560
format_test.go Normal file
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@ -0,0 +1,560 @@
package errors
//import (
// "errors"
// "fmt"
// "io"
// "regexp"
// "strings"
// "testing"
//)
//
//func TestFormatNew(t *testing.T) {
// tests := []struct {
// error
// format string
// want string
// }{{
// New("error"),
// "%s",
// "error",
// }, {
// New("error"),
// "%v",
// "error",
// }, {
// New("error"),
// "%+v",
// "error\n" +
// "game/errors.TestFormatNew\n" +
// "\t.+game/errors/errors/format_test.go:26",
// }, {
// New("error"),
// "%q",
// `"error"`,
// }}
//
// for i, tt := range tests {
// testFormatRegexp(t, i, tt.error, tt.format, tt.want)
// }
//}
//
//func TestFormatErrorf(t *testing.T) {
// tests := []struct {
// error
// format string
// want string
// }{{
// Errorf("%s", "error"),
// "%s",
// "error",
// }, {
// Errorf("%s", "error"),
// "%v",
// "error",
// }, {
// Errorf("%s", "error"),
// "%+v",
// "error\n" +
// "game/errors.TestFormatErrorf\n" +
// "\t.+game/errors/errors/format_test.go:56",
// }}
//
// for i, tt := range tests {
// testFormatRegexp(t, i, tt.error, tt.format, tt.want)
// }
//}
//
//func TestFormatWrap(t *testing.T) {
// tests := []struct {
// error
// format string
// want string
// }{{
// Wrap(New("error"), "error2"),
// "%s",
// "error2: error",
// }, {
// Wrap(New("error"), "error2"),
// "%v",
// "error2: error",
// }, {
// Wrap(New("error"), "error2"),
// "%+v",
// "error\n" +
// "game/errors.TestFormatWrap\n" +
// "\t.+game/errors/errors/format_test.go:82",
// }, {
// Wrap(io.EOF, "error"),
// "%s",
// "error: EOF",
// }, {
// Wrap(io.EOF, "error"),
// "%v",
// "error: EOF",
// }, {
// Wrap(io.EOF, "error"),
// "%+v",
// "EOF\n" +
// "error\n" +
// "game/errors.TestFormatWrap\n" +
// "\t.+game/errors/errors/format_test.go:96",
// }, {
// Wrap(Wrap(io.EOF, "error1"), "error2"),
// "%+v",
// "EOF\n" +
// "error1\n" +
// "game/errors.TestFormatWrap\n" +
// "\t.+game/errors/errors/format_test.go:103\n",
// }, {
// Wrap(New("error with space"), "context"),
// "%q",
// `"context: error with space"`,
// }}
//
// for i, tt := range tests {
// testFormatRegexp(t, i, tt.error, tt.format, tt.want)
// }
//}
//
//func TestFormatWrapf(t *testing.T) {
// tests := []struct {
// error
// format string
// want string
// }{{
// Wrapf(io.EOF, "error%d", 2),
// "%s",
// "error2: EOF",
// }, {
// Wrapf(io.EOF, "error%d", 2),
// "%v",
// "error2: EOF",
// }, {
// Wrapf(io.EOF, "error%d", 2),
// "%+v",
// "EOF\n" +
// "error2\n" +
// "game/errors.TestFormatWrapf\n" +
// "\t.+game/errors/errors/format_test.go:134",
// }, {
// Wrapf(New("error"), "error%d", 2),
// "%s",
// "error2: error",
// }, {
// Wrapf(New("error"), "error%d", 2),
// "%v",
// "error2: error",
// }, {
// Wrapf(New("error"), "error%d", 2),
// "%+v",
// "error\n" +
// "game/errors.TestFormatWrapf\n" +
// "\t.+game/errors/errors/format_test.go:149",
// }}
//
// for i, tt := range tests {
// testFormatRegexp(t, i, tt.error, tt.format, tt.want)
// }
//}
//
//func TestFormatWithStack(t *testing.T) {
// tests := []struct {
// error
// format string
// want []string
// }{{
// WithStack(io.EOF),
// "%s",
// []string{"EOF"},
// }, {
// WithStack(io.EOF),
// "%v",
// []string{"EOF"},
// }, {
// WithStack(io.EOF),
// "%+v",
// []string{"EOF",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:175"},
// }, {
// WithStack(New("error")),
// "%s",
// []string{"error"},
// }, {
// WithStack(New("error")),
// "%v",
// []string{"error"},
// }, {
// WithStack(New("error")),
// "%+v",
// []string{"error",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:189",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:189"},
// }, {
// WithStack(WithStack(io.EOF)),
// "%+v",
// []string{"EOF",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:197",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:197"},
// }, {
// WithStack(WithStack(Wrapf(io.EOF, "message"))),
// "%+v",
// []string{"EOF",
// "message",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:205",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:205",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:205"},
// }, {
// WithStack(Errorf("error%d", 1)),
// "%+v",
// []string{"error1",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:216",
// "game/errors.TestFormatWithStack\n" +
// "\t.+game/errors/errors/format_test.go:216"},
// }}
//
// for i, tt := range tests {
// testFormatCompleteCompare(t, i, tt.error, tt.format, tt.want, true)
// }
//}
//
//func TestFormatWithMessage(t *testing.T) {
// tests := []struct {
// error
// format string
// want []string
// }{{
// WithMessage(New("error"), "error2"),
// "%s",
// []string{"error2: error"},
// }, {
// WithMessage(New("error"), "error2"),
// "%v",
// []string{"error2: error"},
// }, {
// WithMessage(New("error"), "error2"),
// "%+v",
// []string{
// "error",
// "game/errors.TestFormatWithMessage\n" +
// "\t.+game/errors/errors/format_test.go:244",
// "error2"},
// }, {
// WithMessage(io.EOF, "addition1"),
// "%s",
// []string{"addition1: EOF"},
// }, {
// WithMessage(io.EOF, "addition1"),
// "%v",
// []string{"addition1: EOF"},
// }, {
// WithMessage(io.EOF, "addition1"),
// "%+v",
// []string{"EOF", "addition1"},
// }, {
// WithMessage(WithMessage(io.EOF, "addition1"), "addition2"),
// "%v",
// []string{"addition2: addition1: EOF"},
// }, {
// WithMessage(WithMessage(io.EOF, "addition1"), "addition2"),
// "%+v",
// []string{"EOF", "addition1", "addition2"},
// }, {
// Wrap(WithMessage(io.EOF, "error1"), "error2"),
// "%+v",
// []string{"EOF", "error1", "error2",
// "game/errors.TestFormatWithMessage\n" +
// "\t.+game/errors/errors/format_test.go:272"},
// }, {
// WithMessage(Errorf("error%d", 1), "error2"),
// "%+v",
// []string{"error1",
// "game/errors.TestFormatWithMessage\n" +
// "\t.+game/errors/errors/format_test.go:278",
// "error2"},
// }, {
// WithMessage(WithStack(io.EOF), "error"),
// "%+v",
// []string{
// "EOF",
// "game/errors.TestFormatWithMessage\n" +
// "\t.+game/errors/errors/format_test.go:285",
// "error"},
// }, {
// WithMessage(Wrap(WithStack(io.EOF), "inside-error"), "outside-error"),
// "%+v",
// []string{
// "EOF",
// "game/errors.TestFormatWithMessage\n" +
// "\t.+game/errors/errors/format_test.go:293",
// "inside-error",
// "game/errors.TestFormatWithMessage\n" +
// "\t.+game/errors/errors/format_test.go:293",
// "outside-error"},
// }}
//
// for i, tt := range tests {
// testFormatCompleteCompare(t, i, tt.error, tt.format, tt.want, true)
// }
//}
//
//func TestFormatGeneric(t *testing.T) {
// starts := []struct {
// err error
// want []string
// }{
// {New("new-error"), []string{
// "new-error",
// "game/errors.TestFormatGeneric\n" +
// "\t.+game/errors/errors/format_test.go:315"},
// }, {Errorf("errorf-error"), []string{
// "errorf-error",
// "game/errors.TestFormatGeneric\n" +
// "\t.+game/errors/errors/format_test.go:319"},
// }, {errors.New("errors-new-error"), []string{
// "errors-new-error"},
// },
// }
//
// wrappers := []wrapper{
// {
// func(err error) error { return WithMessage(err, "with-message") },
// []string{"with-message"},
// }, {
// func(err error) error { return WithStack(err) },
// []string{
// "game/errors.(func·002|TestFormatGeneric.func2)\n\t" +
// ".+game/errors/errors/format_test.go:333",
// },
// }, {
// func(err error) error { return Wrap(err, "wrap-error") },
// []string{
// "wrap-error",
// "game/errors.(func·003|TestFormatGeneric.func3)\n\t" +
// ".+game/errors/errors/format_test.go:339",
// },
// }, {
// func(err error) error { return Wrapf(err, "wrapf-error%d", 1) },
// []string{
// "wrapf-error1",
// "game/errors.(func·004|TestFormatGeneric.func4)\n\t" +
// ".+game/errors/errors/format_test.go:346",
// },
// },
// }
//
// for s := range starts {
// err := starts[s].err
// want := starts[s].want
// testFormatCompleteCompare(t, s, err, "%+v", want, false)
// testGenericRecursive(t, err, want, wrappers, 3)
// }
//}
//
//func wrappedNew(message string) error { // This function will be mid-stack inlined in go 1.12+
// return New(message)
//}
//
//func TestFormatWrappedNew(t *testing.T) {
// tests := []struct {
// error
// format string
// want string
// }{{
// wrappedNew("error"),
// "%+v",
// "error\n" +
// "game/errors.wrappedNew\n" +
// "\t.+game/errors/errors/format_test.go:364\n" +
// "game/errors.TestFormatWrappedNew\n" +
// "\t.+game/errors/errors/format_test.go:373",
// }}
//
// for i, tt := range tests {
// testFormatRegexp(t, i, tt.error, tt.format, tt.want)
// }
//}
//
//func testFormatRegexp(t *testing.T, n int, arg interface{}, format, want string) {
// t.Helper()
// got := fmt.Sprintf(format, arg)
// gotLines := strings.SplitN(got, "\n", -1)
// wantLines := strings.SplitN(want, "\n", -1)
//
// if len(wantLines) > len(gotLines) {
// t.Errorf("test %d: wantLines(%d) > gotLines(%d):\n got: %q\nwant: %q", n+1, len(wantLines), len(gotLines), got, want)
// return
// }
//
// for i, w := range wantLines {
// match, err := regexp.MatchString(w, gotLines[i])
// if err != nil {
// t.Fatal(err)
// }
// if !match {
// t.Errorf("test %d: line %d: fmt.Sprintf(%q, err):\n got: %q\nwant: %q", n+1, i+1, format, got, want)
// }
// }
//}
//
//var stackLineR = regexp.MustCompile(`\.`)
//
//// parseBlocks parses input into a slice, where:
//// - incase entry contains a newline, its a stacktrace
//// - incase entry contains no newline, its a solo line.
////
//// Detecting stack boundaries only works incase the WithStack-calls are
//// to be found on the same line, thats why it is optionally here.
////
//// Example use:
////
//// for _, e := range blocks {
//// if strings.ContainsAny(e, "\n") {
//// // Match as stack
//// } else {
//// // Match as line
//// }
//// }
////
//func parseBlocks(input string, detectStackboundaries bool) ([]string, error) {
// var blocks []string
//
// stack := ""
// wasStack := false
// lines := map[string]bool{} // already found lines
//
// for _, l := range strings.Split(input, "\n") {
// isStackLine := stackLineR.MatchString(l)
//
// switch {
// case !isStackLine && wasStack:
// blocks = append(blocks, stack, l)
// stack = ""
// lines = map[string]bool{}
// case isStackLine:
// if wasStack {
// // Detecting two stacks after another, possible cause lines match in
// // our tests due to WithStack(WithStack(io.EOF)) on same line.
// if detectStackboundaries {
// if lines[l] {
// if len(stack) == 0 {
// return nil, errors.New("len of block must not be zero here")
// }
//
// blocks = append(blocks, stack)
// stack = l
// lines = map[string]bool{l: true}
// continue
// }
// }
//
// stack = stack + "\n" + l
// } else {
// stack = l
// }
// lines[l] = true
// case !isStackLine && !wasStack:
// blocks = append(blocks, l)
// default:
// return nil, errors.New("must not happen")
// }
//
// wasStack = isStackLine
// }
//
// // Use up stack
// if stack != "" {
// blocks = append(blocks, stack)
// }
// return blocks, nil
//}
//
//func testFormatCompleteCompare(t *testing.T, n int, arg interface{}, format string, want []string, detectStackBoundaries bool) {
// gotStr := fmt.Sprintf(format, arg)
//
// got, err := parseBlocks(gotStr, detectStackBoundaries)
// if err != nil {
// t.Fatal(err)
// }
//
// if len(got) != len(want) {
// t.Fatalf("test %d: fmt.Sprintf(%s, err) -> wrong number of blocks: got(%d) want(%d)\n got: %s\nwant: %s\ngotStr: %q",
// n+1, format, len(got), len(want), prettyBlocks(got), prettyBlocks(want), gotStr)
// }
//
// for i := range got {
// if strings.ContainsAny(want[i], "\n") {
// // Match as stack
// match, err := regexp.MatchString(want[i], got[i])
// if err != nil {
// t.Fatal(err)
// }
// if !match {
// t.Fatalf("test %d: block %d: fmt.Sprintf(%q, err):\ngot:\n%q\nwant:\n%q\nall-got:\n%s\nall-want:\n%s\n",
// n+1, i+1, format, got[i], want[i], prettyBlocks(got), prettyBlocks(want))
// }
// } else {
// // Match as message
// if got[i] != want[i] {
// t.Fatalf("test %d: fmt.Sprintf(%s, err) at block %d got != want:\n got: %q\nwant: %q", n+1, format, i+1, got[i], want[i])
// }
// }
// }
//}
//
//type wrapper struct {
// wrap func(err error) error
// want []string
//}
//
//func prettyBlocks(blocks []string) string {
// var out []string
//
// for _, b := range blocks {
// out = append(out, fmt.Sprintf("%v", b))
// }
//
// return " " + strings.Join(out, "\n ")
//}
//
//func testGenericRecursive(t *testing.T, beforeErr error, beforeWant []string, list []wrapper, maxDepth int) {
// if len(beforeWant) == 0 {
// panic("beforeWant must not be empty")
// }
// for _, w := range list {
// if len(w.want) == 0 {
// panic("want must not be empty")
// }
//
// err := w.wrap(beforeErr)
//
// // Copy required cause append(beforeWant, ..) modified beforeWant subtly.
// beforeCopy := make([]string, len(beforeWant))
// copy(beforeCopy, beforeWant)
//
// beforeWant := beforeCopy
// last := len(beforeWant) - 1
// var want []string
//
// // Merge two stacks behind each other.
// if strings.ContainsAny(beforeWant[last], "\n") && strings.ContainsAny(w.want[0], "\n") {
// want = append(beforeWant[:last], append([]string{beforeWant[last] + "((?s).*)" + w.want[0]}, w.want[1:]...)...)
// } else {
// want = append(beforeWant, w.want...)
// }
//
// testFormatCompleteCompare(t, maxDepth, err, "%+v", want, false)
// if maxDepth > 0 {
// testGenericRecursive(t, err, want, list, maxDepth-1)
// }
// }
//}

3
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module git.bit5.ru/backend/errors
go 1.13

51
json_test.go Normal file
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package errors
import (
"encoding/json"
"regexp"
"testing"
)
func TestFrameMarshalText(t *testing.T) {
var tests = []struct {
Frame
want string
}{{
initpc,
`^game/errors\.init(\.ializers)? .+/game/errors/stack_test.go:\d+$`,
}, {
0,
`^unknown$`,
}}
for i, tt := range tests {
got, err := tt.Frame.MarshalText()
if err != nil {
t.Fatal(err)
}
if !regexp.MustCompile(tt.want).Match(got) {
t.Errorf("test %d: MarshalJSON:\n got %q\n want %q", i+1, string(got), tt.want)
}
}
}
func TestFrameMarshalJSON(t *testing.T) {
var tests = []struct {
Frame
want string
}{{
initpc,
`^"game/errors\.init(\.ializers)? .+/game/errors/stack_test.go:\d+"$`,
}, {
0,
`^"unknown"$`,
}}
for i, tt := range tests {
got, err := json.Marshal(tt.Frame)
if err != nil {
t.Fatal(err)
}
if !regexp.MustCompile(tt.want).Match(got) {
t.Errorf("test %d: MarshalJSON:\n got %q\n want %q", i+1, string(got), tt.want)
}
}
}

198
stack.go Normal file
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package errors
import (
"fmt"
"io"
"path"
"runtime"
"strconv"
"strings"
)
// Frame represents a program counter inside a stack frame.
// For historical reasons if Frame is interpreted as a uintptr
// its value represents the program counter + 1.
type Frame uintptr
// pc returns the program counter for this frame;
// multiple frames may have the same PC value.
func (f Frame) pc() uintptr { return uintptr(f) - 1 }
// file returns the full path to the file that contains the
// function for this Frame's pc.
func (f Frame) file() string {
fn := runtime.FuncForPC(f.pc())
if fn == nil {
return "unknown"
}
file, _ := fn.FileLine(f.pc())
return file
}
// line returns the line number of source code of the
// function for this Frame's pc.
func (f Frame) line() int {
fn := runtime.FuncForPC(f.pc())
if fn == nil {
return 0
}
_, line := fn.FileLine(f.pc())
return line
}
// name returns the name of this function, if known.
func (f Frame) name() string {
fn := runtime.FuncForPC(f.pc())
if fn == nil {
return "unknown"
}
return fn.Name()
}
// Format formats the frame according to the fmt.Formatter interface.
//
// %s source file
// %d source line
// %n function name
// %v equivalent to %s:%d
//
// Format accepts flags that alter the printing of some verbs, as follows:
//
// %+s function name and path of source file relative to the compile time
// GOPATH separated by \n\t (<funcname>\n\t<path>)
// %+v equivalent to %+s:%d
func (f Frame) Format(s fmt.State, verb rune) {
switch verb {
case 's':
switch {
case s.Flag('-'):
io.WriteString(s, path.Ext(f.name()))
io.WriteString(s, " ")
dir, file := path.Split(f.file())
io.WriteString(s, path.Join(path.Base(path.Dir(dir)), path.Base(dir), file))
case s.Flag('+'):
io.WriteString(s, f.name())
io.WriteString(s, "\n\t")
io.WriteString(s, f.file())
default:
io.WriteString(s, path.Base(f.file()))
}
case 'd':
io.WriteString(s, strconv.Itoa(f.line()))
case 'n':
io.WriteString(s, funcname(f.name()))
case 'v':
if s.Flag('-') {
io.WriteString(s, "[")
}
f.Format(s, 's')
io.WriteString(s, ":")
f.Format(s, 'd')
if s.Flag('-') {
io.WriteString(s, "]")
}
}
}
// MarshalText formats a stacktrace Frame as a text string. The output is the
// same as that of fmt.Sprintf("%+v", f), but without newlines or tabs.
func (f Frame) MarshalText() ([]byte, error) {
name := f.name()
if name == "unknown" {
return []byte(name), nil
}
return []byte(fmt.Sprintf("%s %s:%d", name, f.file(), f.line())), nil
}
// StackTrace is stack of Frames from innermost (newest) to outermost (oldest).
type StackTrace []Frame
// Format formats the stack of Frames according to the fmt.Formatter interface.
//
// %s lists source files for each Frame in the stack
// %v lists the source file and line number for each Frame in the stack
//
// Format accepts flags that alter the printing of some verbs, as follows:
//
// %+v Prints filename, function, and line number for each Frame in the stack.
func (st StackTrace) Format(s fmt.State, verb rune) {
switch verb {
case 'v':
switch {
case s.Flag('+'):
for _, f := range st {
io.WriteString(s, "\n")
f.Format(s, verb)
}
case s.Flag('-'):
for _, f := range st {
io.WriteString(s, " ")
f.Format(s, verb)
}
case s.Flag('#'):
fmt.Fprintf(s, "%#v", []Frame(st))
default:
st.formatSlice(s, verb)
}
case 's':
st.formatSlice(s, verb)
}
}
// formatSlice will format this StackTrace into the given buffer as a slice of
// Frame, only valid when called with '%s' or '%v'.
func (st StackTrace) formatSlice(s fmt.State, verb rune) {
io.WriteString(s, "[")
for i, f := range st {
if i > 0 {
io.WriteString(s, " ")
}
f.Format(s, verb)
}
io.WriteString(s, "]")
}
// stack represents a stack of program counters.
type stack []uintptr
func (s *stack) Format(st fmt.State, verb rune) {
switch verb {
case 'v':
switch {
case st.Flag('+'):
for _, pc := range *s {
f := Frame(pc)
fmt.Fprintf(st, "\n%+v", f)
}
case st.Flag('-'):
for _, pc := range *s {
f := Frame(pc)
fmt.Fprintf(st, " < %-v", f)
}
}
}
}
func (s *stack) StackTrace() StackTrace {
f := make([]Frame, len(*s))
for i := 0; i < len(f); i++ {
f[i] = Frame((*s)[i])
}
return f
}
func callers() *stack {
const depth = 7
var pcs [depth]uintptr
n := runtime.Callers(3, pcs[:])
var st stack = pcs[0:n]
return &st
}
// funcname removes the path prefix component of a function's name reported by func.Name().
func funcname(name string) string {
i := strings.LastIndex(name, "/")
name = name[i+1:]
i = strings.Index(name, ".")
return name[i+1:]
}

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stack_test.go Normal file
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package errors
import (
// "fmt"
"runtime"
// "testing"
)
var initpc = caller()
//type X struct{}
//
//// val returns a Frame pointing to itself.
//func (x X) val() Frame {
// return caller()
//}
//
//// ptr returns a Frame pointing to itself.
//func (x *X) ptr() Frame {
// return caller()
//}
//
//func TestFrameFormat(t *testing.T) {
// var tests = []struct {
// Frame
// format string
// want string
// }{{
// initpc,
// "%s",
// "stack_test.go",
// }, {
// initpc,
// "%+s",
// "game/errors/errors.init\n" +
// "\t.+game/errors/errors/stack_test.go",
// }, {
// 0,
// "%s",
// "unknown",
// }, {
// 0,
// "%+s",
// "unknown",
// }, {
// initpc,
// "%d",
// "9",
// }, {
// 0,
// "%d",
// "0",
// }, {
// initpc,
// "%n",
// "init",
// }, {
// func() Frame {
// var x X
// return x.ptr()
// }(),
// "%n",
// `\(\*X\).ptr`,
// }, {
// func() Frame {
// var x X
// return x.val()
// }(),
// "%n",
// "X.val",
// }, {
// 0,
// "%n",
// "",
// }, {
// initpc,
// "%v",
// "stack_test.go:9",
// }, {
// initpc,
// "%+v",
// "game/errors/errors.init\n" +
// "\t.+game/errors/errors/stack_test.go:9",
// }, {
// 0,
// "%v",
// "unknown:0",
// }}
//
// for i, tt := range tests {
// testFormatRegexp(t, i, tt.Frame, tt.format, tt.want)
// }
//}
//
//func TestFuncname(t *testing.T) {
// tests := []struct {
// name, want string
// }{
// {"", ""},
// {"runtime.main", "main"},
// {"game/errors/errors.funcname", "funcname"},
// {"funcname", "funcname"},
// {"io.copyBuffer", "copyBuffer"},
// {"main.(*R).Write", "(*R).Write"},
// }
//
// for _, tt := range tests {
// got := funcname(tt.name)
// want := tt.want
// if got != want {
// t.Errorf("funcname(%q): want: %q, got %q", tt.name, want, got)
// }
// }
//}
//
//func TestStackTrace(t *testing.T) {
// tests := []struct {
// err error
// want []string
// }{{
// New("ooh"), []string{
// "game/errors/errors.TestStackTrace\n" +
// "\t.+game/errors/errors/stack_test.go:121",
// },
// }, {
// Wrap(New("ooh"), "ahh"), []string{
// "game/errors/errors.TestStackTrace\n" +
// "\t.+game/errors/errors/stack_test.go:126", // this is the stack of Wrap, not New
// },
// }, {
// Cause(Wrap(New("ooh"), "ahh")), []string{
// "game/errors/errors.TestStackTrace\n" +
// "\t.+game/errors/errors/stack_test.go:131", // this is the stack of New
// },
// }, {
// func() error { return New("ooh") }(), []string{
// `game/errors/errors.TestStackTrace.func1` +
// "\n\t.+game/errors/errors/stack_test.go:136", // this is the stack of New
// "game/errors/errors.TestStackTrace\n" +
// "\t.+game/errors/errors/stack_test.go:136", // this is the stack of New's caller
// },
// }, {
// Cause(func() error {
// return func() error {
// return Errorf("hello %s", fmt.Sprintf("world"))
// }()
// }()), []string{
// `game/errors/errors.TestStackTrace.func2.1` +
// "\n\t.+game/errors/errors/stack_test.go:145", // this is the stack of Errorf
// `game/errors/errors.TestStackTrace.func2` +
// "\n\t.+game/errors/errors/stack_test.go:146", // this is the stack of Errorf's caller
// "game/errors/errors.TestStackTrace\n" +
// "\t.+game/errors/errors/stack_test.go:147", // this is the stack of Errorf's caller's caller
// },
// }}
// for i, tt := range tests {
// x, ok := tt.err.(interface {
// StackTrace() StackTrace
// })
// if !ok {
// t.Errorf("expected %#v to implement StackTrace() StackTrace", tt.err)
// continue
// }
// st := x.StackTrace()
// for j, want := range tt.want {
// testFormatRegexp(t, i, st[j], "%+v", want)
// }
// }
//}
//
//func stackTrace() StackTrace {
// const depth = 8
// var pcs [depth]uintptr
// n := runtime.Callers(1, pcs[:])
// var st stack = pcs[0:n]
// return st.StackTrace()
//}
//
//func TestStackTraceFormat(t *testing.T) {
// tests := []struct {
// StackTrace
// format string
// want string
// }{{
// nil,
// "%s",
// `\[\]`,
// }, {
// nil,
// "%v",
// `\[\]`,
// }, {
// nil,
// "%+v",
// "",
// }, {
// nil,
// "%#v",
// `\[\]errors.Frame\(nil\)`,
// }, {
// make(StackTrace, 0),
// "%s",
// `\[\]`,
// }, {
// make(StackTrace, 0),
// "%v",
// `\[\]`,
// }, {
// make(StackTrace, 0),
// "%+v",
// "",
// }, {
// make(StackTrace, 0),
// "%#v",
// `\[\]errors.Frame{}`,
// }, {
// stackTrace()[:2],
// "%s",
// `\[stack_test.go stack_test.go\]`,
// }, {
// stackTrace()[:2],
// "%v",
// `\[stack_test.go:174 stack_test.go:221\]`,
// }, {
// stackTrace()[:2],
// "%+v",
// "\n" +
// "game/errors/errors.stackTrace\n" +
// "\t.+game/errors/errors/stack_test.go:174\n" +
// "game/errors/errors.TestStackTraceFormat\n" +
// "\t.+game/errors/errors/stack_test.go:225",
// }, {
// stackTrace()[:2],
// "%#v",
// `\[\]errors.Frame{stack_test.go:174, stack_test.go:233}`,
// }}
//
// for i, tt := range tests {
// testFormatRegexp(t, i, tt.StackTrace, tt.format, tt.want)
// }
//}
//
// a version of runtime.Caller that returns a Frame, not a uintptr.
func caller() Frame {
var pcs [3]uintptr
n := runtime.Callers(2, pcs[:])
frames := runtime.CallersFrames(pcs[:n])
frame, _ := frames.Next()
return Frame(frame.PC)
}