Add errors package with metadata support

errors/doc.go

@@ -0,0 +1,5 @@
+// Package errors extends the standard library errors package
+// with additional APIs to:
+// - wrap errors with additional metadata
+// - read attached metadata from errors
+package errors

errors/errors.go

@@ -0,0 +1,69 @@
+package errors
+
+import (
+	"errors"
+	"strings"
+)
+
+// Aliases to the standard error types
+var (
+	New    = errors.New
+	Is     = errors.Is
+	As     = errors.As
+	Unwrap = errors.Unwrap
+	Join   = errors.Join
+)
+
+// ErrorData is an error that has key-value metadata attached to it.
+type ErrorData struct {
+	err  error
+	data map[string]string
+}
+
+// Error returns the error message and any attached metadata.
+func (e *ErrorData) Error() string {
+	md := []string{}
+
+	for k, v := range e.data {
+		md = append(md, k+"="+v)
+	}
+
+	return e.err.Error() + " [" + strings.Join(md, ", ") + "]"
+}
+
+// Unwrap returns the underlying error.
+func (e *ErrorData) Unwrap() error {
+	return e.err
+}
+
+// Is returns true if the error is the same as the target error.
+func (e *ErrorData) Is(target error) bool {
+	return Is(e.err, target)
+}
+
+// Data returns the attached metadata.
+func (e *ErrorData) Data() map[string]string {
+	return e.data
+}
+
+// Wrap attaches additional metadata to an error.
+func Wrap(err error, attrs ...string) error {
+	if err == nil {
+		return nil
+	}
+
+	if len(attrs)%2 != 0 {
+		panic("[xtools/errors] attrs must be key/value pairs")
+	}
+
+	e := &ErrorData{
+		err:  err,
+		data: map[string]string{},
+	}
+
+	for i := 0; i < len(attrs); i += 2 {
+		e.data[attrs[i]] = attrs[i+1]
+	}
+
+	return e
+}

errors/errors_test.go

@@ -0,0 +1,55 @@
+package errors_test
+
+import (
+	"fmt"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/gojekfarm/xtools/errors"
+)
+
+func TestWrap(t *testing.T) {
+	err := errors.New("test error")
+
+	wrapped := errors.Wrap(err, "foo", "bar")
+
+	assert.Equal(t, "test error [foo=bar]", wrapped.Error())
+	assert.ErrorIs(t, wrapped, err)
+	assert.EqualError(t, errors.Unwrap(wrapped), err.Error())
+
+	var data *errors.ErrorData
+	assert.True(t, errors.As(wrapped, &data))
+	assert.EqualValues(t, map[string]string{"foo": "bar"}, data.Data())
+}
+
+func TestWrap_PanicsOnOddNumberOfAttrs(t *testing.T) {
+	assert.Panics(t, func() {
+		errors.Wrap(errors.New("test error"), "foo")
+	})
+}
+
+func TestWrap_ReturnsNilIfErrIsNil(t *testing.T) {
+	assert.Nil(t, errors.Wrap(nil, "foo", "bar"))
+}
+
+func ExampleWrap() {
+	err := errors.New("test error")
+
+	// Wrap the error with some key-value pairs
+	wrapped := errors.Wrap(
+		err,
+		"foo", "bar",
+		"baz", "qux",
+	)
+
+	// errors.Is will check for the original error
+	fmt.Println(errors.Is(wrapped, err))
+
+	// Use errors.As to read attached metadata
+	var errData *errors.ErrorData
+
+	errors.As(wrapped, &errData)
+
+	fmt.Println(errData.Data())
+}

errors/go.mod

@@ -0,0 +1,11 @@
+module github.com/gojekfarm/xtools/errors
+
+go 1.18
+
+require github.com/stretchr/testify v1.10.0
+
+require (
+	github.com/davecgh/go-spew v1.1.1 // indirect
+	github.com/pmezard/go-difflib v1.0.0 // indirect
+	gopkg.in/yaml.v3 v3.0.1 // indirect
+)

errors/go.sum

@@ -0,0 +1,10 @@
+github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
+github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
+github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
+github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/testify v1.10.0 h1:Xv5erBjTwe/5IxqUQTdXv5kgmIvbHo3QQyRwhJsOfJA=
+github.com/stretchr/testify v1.10.0/go.mod h1:r2ic/lqez/lEtzL7wO/rwa5dbSLXVDPFyf8C91i36aY=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1 h1:fxVm/GzAzEWqLHuvctI91KS9hhNmmWOoWu0XTYJS7CA=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=