feat: add XError to support more contextual error handling

xerror/stack.go

@@ -16,7 +16,26 @@ import (
 type Stack struct {
 	Func string `json:"func"`
 	File string `json:"file"`
-	Line string `json:"line"`
+	Line int    `json:"line"`
+}
+
+// Stacks returns stack trace array generated by pkg/errors
+func (e *XError) Stacks() []*Stack {
+	resp := make([]*Stack, len(*e.stack))
+	for i, st := range *e.stack {
+		f := frame(st)
+		resp[i] = &Stack{
+			Func: f.name(),
+			File: f.file(),
+			Line: f.line(),
+		}
+	}
+	return resp
+}
+
+// StackTrace returns stack trace which is compatible with pkg/errors
+func (e *XError) StackTrace() StackTrace {
+	return e.stack.StackTrace()
 }
 
 // ---------------------------------------

xerror/xerror.go

@@ -4,10 +4,202 @@
 // Package xerror implements helpers for errors
 package xerror
 
-// Unwrap if err is nil then it returns a valid value
+import (
+	"errors"
+	"fmt"
+	"io"
+	"strings"
+
+	"github.com/duke-git/lancet/v2/random"
+)
+
+// XError is to handle error related information.
+type XError struct {
+	id      string
+	message string
+	stack   *stack
+	cause   error
+	values  map[string]any
+}
+
+// New creates a new XError with message
+func New(format string, args ...any) *XError {
+	err := newXError()
+	err.message = fmt.Sprintf(format, args...)
+	return err
+}
+
+// Wrap creates a new XError and add message.
+func Wrap(cause error, message ...any) *XError {
+	err := newXError()
+
+	if len(message) > 0 {
+		var newMsgs []string
+		for _, m := range message {
+			newMsgs = append(newMsgs, fmt.Sprintf("%v", m))
+		}
+		err.message = strings.Join(newMsgs, " ")
+	}
+
+	err.cause = cause
+
+	return err
+}
+
+// Unwrap returns unwrapped XError from err by errors.As. If no XError, returns nil
+func Unwrap(err error) *XError {
+	var e *XError
+	if errors.As(err, &e) {
+		return e
+	}
+	return nil
+}
+
+func newXError() *XError {
+	id, err := random.UUIdV4()
+	if err != nil {
+		return nil
+	}
+
+	return &XError{
+		id:     id,
+		stack:  callers(),
+		values: make(map[string]any),
+	}
+}
+
+func (e *XError) copy(dest *XError) {
+	dest.message = e.message
+	dest.id = e.id
+	dest.cause = e.cause
+
+	for k, v := range e.values {
+		dest.values[k] = v
+	}
+}
+
+// Error implements standard error interface.
+func (e *XError) Error() string {
+	msg := e.message
+	cause := e.cause
+
+	if cause == nil {
+		return msg
+	}
+
+	msg = fmt.Sprintf("%s: %v", msg, cause.Error())
+
+	return msg
+}
+
+// Format returns:
+// - %v, %s, %q: formatted message
+// - %+v: formatted message with stack trace
+func (e *XError) Format(s fmt.State, verb rune) {
+	switch verb {
+	case 'v':
+		if s.Flag('+') {
+			_, _ = io.WriteString(s, e.Error())
+			e.stack.Format(s, verb)
+			return
+		}
+		fallthrough
+	case 's':
+		_, _ = io.WriteString(s, e.Error())
+	case 'q':
+		fmt.Fprintf(s, "%q", e.Error())
+	}
+}
+
+// Wrap creates a new XError and copy message and id to new one.
+func (e *XError) Wrap(cause error) *XError {
+	err := newXError()
+	e.copy(err)
+	err.cause = cause
+	return err
+}
+
+// Unwrap compatible with github.com/pkg/errors
+func (e *XError) Unwrap() error {
+	return e.cause
+}
+
+// With adds key and value related to the error object
+func (e *XError) With(key string, value any) *XError {
+	e.values[key] = value
+	return e
+}
+
+// Is checks if target error is XError and Error.id of two errors are matched.
+func (e *XError) Is(target error) bool {
+	var err *XError
+
+	if errors.As(target, &err) {
+		if e.id != "" && e.id == err.id {
+			return true
+		}
+	}
+
+	return e == target
+}
+
+// Id sets id to check equality in XError.Is
+func (e *XError) Id(id string) *XError {
+	e.id = id
+	return e
+}
+
+// Values returns map of key and value that is set by With. All wrapped xerror.XError key and values will be merged.
+// Key and values of wrapped error is overwritten by upper xerror.XError.
+func (e *XError) Values() map[string]any {
+	var values map[string]any
+
+	if cause := e.Unwrap(); cause != nil {
+		if err, ok := cause.(*XError); ok {
+			values = err.Values()
+		}
+	}
+
+	if values == nil {
+		values = make(map[string]any)
+	}
+
+	for key, value := range e.values {
+		values[key] = value
+	}
+
+	return values
+}
+
+type errInfo struct {
+	Message    string         `json:"message"`
+	Id         string         `json:"id"`
+	StackTrace []*Stack       `json:"stacktrace"`
+	Cause      error          `json:"cause"`
+	Values     map[string]any `json:"values"`
+}
+
+// Info returns information of xerror, which can be printed.
+func (e *XError) Info() *errInfo {
+	errInfo := &errInfo{
+		Message:    e.message,
+		Id:         e.id,
+		StackTrace: e.Stacks(),
+		Cause:      e.cause,
+		Values:     make(map[string]any),
+	}
+
+	for k, v := range e.values {
+		errInfo.Values[k] = v
+	}
+
+	return errInfo
+}
+
+// TryUnwrap if err is nil then it returns a valid value
 // If err is not nil, Unwrap panics with err.
 // Play: https://go.dev/play/p/w84d7Mb3Afk
-func Unwrap[T any](val T, err error) T {
+func TryUnwrap[T any](val T, err error) T {
 	if err != nil {
 		panic(err)
 	}

xerror/xerror_example_test.go

@@ -6,8 +6,8 @@ import (
 	"strconv"
 )
 
-func ExampleUnwrap() {
-	result1 := Unwrap(strconv.Atoi("42"))
+func ExampleTryUnwrap() {
+	result1 := TryUnwrap(strconv.Atoi("42"))
 	fmt.Println(result1)
 
 	_, err := strconv.Atoi("4o2")
@@ -17,7 +17,7 @@ func ExampleUnwrap() {
 		fmt.Println(result2)
 	}()
 
-	Unwrap(strconv.Atoi("4o2"))
+	TryUnwrap(strconv.Atoi("4o2"))
 
 	// Output:
 	// 42

xerror/xerror_test.go

@@ -1,19 +1,21 @@
 package xerror
 
 import (
+	"errors"
 	"strconv"
+	"strings"
 	"testing"
 
 	"github.com/duke-git/lancet/v2/internal"
 )
 
-func TestUnwrap(t *testing.T) {
-	assert := internal.NewAssert(t, "TestUnwrap")
-	assert.Equal(42, Unwrap(strconv.Atoi("42")))
+func TestTryUnwrap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestTryUnwrap")
+	assert.Equal(42, TryUnwrap(strconv.Atoi("42")))
 }
 
-func TestUnwrapFail(t *testing.T) {
-	assert := internal.NewAssert(t, "TestUnwrapFail")
+func TestTryUnwrapFail(t *testing.T) {
+	assert := internal.NewAssert(t, "TestTryUnwrapFail")
 
 	_, err := strconv.Atoi("4o2")
 	defer func() {
@@ -21,5 +23,85 @@ func TestUnwrapFail(t *testing.T) {
 		assert.Equal(err.Error(), v.(*strconv.NumError).Error())
 	}()
 
-	Unwrap(strconv.Atoi("4o2"))
+	TryUnwrap(strconv.Atoi("4o2"))
+}
+
+func TestNew(t *testing.T) {
+	assert := internal.NewAssert(t, "TestNew")
+
+	err := New("error occurs")
+	assert.Equal("error occurs", err.Error())
+}
+
+func TestWrap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestWrap")
+
+	err := New("wrong password")
+	wrapErr := Wrap(err, "error")
+
+	assert.Equal("error: wrong password", wrapErr.Error())
+}
+
+func TestXError_Wrap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestXError_Wrap")
+
+	err1 := New("error").With("level", "high")
+	err2 := err1.Wrap(errors.New("bad"))
+
+	assert.Equal("error: bad", err2.Error())
+}
+
+func TestXError_Unwrap(t *testing.T) {
+	assert := internal.NewAssert(t, "TestXError_Unwrap")
+
+	err1 := New("error").With("level", "high")
+
+	err2 := err1.Wrap(errors.New("bad"))
+
+	err := err2.Unwrap()
+
+	assert.Equal("bad", err.Error())
+}
+
+func TestXError_StackTrace(t *testing.T) {
+	assert := internal.NewAssert(t, "TestXError_StackTrace")
+
+	err := New("error")
+
+	stacks := err.Stacks()
+
+	assert.Equal(3, len(stacks))
+	assert.Equal("github.com/duke-git/lancet/v2/xerror.TestXError_StackTrace", stacks[0].Func)
+	assert.Equal(69, stacks[0].Line)
+	assert.Equal(true, strings.Contains(stacks[0].File, "xerror_test.go"))
+}
+
+func TestXError_With_Id_Is_Values(t *testing.T) {
+	assert := internal.NewAssert(t, "TestXError_With_Id_Is_Values")
+
+	baseErr := New("baseError")
+	err1 := New("error1").Id("e001").With("level", "high")
+	err2 := New("error2").Id("e002").With("level", "low")
+
+	err := err1.Wrap(baseErr).With("v", "1.0")
+
+	assert.Equal(true, errors.Is(err, baseErr))
+	assert.NotEqual(err, err1)
+	assert.IsNotNil(err.Values()["v"])
+	assert.IsNil(err1.Values()["v"])
+
+	assert.Equal(false, errors.Is(err, err2))
+}
+
+func TestXError_Info(t *testing.T) {
+	assert := internal.NewAssert(t, "TestXError_Info")
+
+	cause := errors.New("error")
+	err := Wrap(cause, "invalid username").Id("e001").With("level", "high")
+
+	errInfo := err.Info()
+	assert.Equal("invalid username", errInfo.Message)
+	assert.Equal("e001", errInfo.Id)
+	assert.Equal(cause, errInfo.Cause)
+	assert.Equal("high", errInfo.Values["level"])
 }