From 34f2caf5168fabeb85b11df5176900f586bd5a08 Mon Sep 17 00:00:00 2001
From: Jan Semmelink <jan@uafrica.com>
Date: Fri, 17 Sep 2021 14:12:48 +0200
Subject: [PATCH] Added errors.Is()
---
errors/error.go | 22 +++++++++++++++++++++-
errors/errors.go | 5 +++++
errors/errors_test.go | 40 ++++++++++++++++++++++++++++++++++++++++
3 files changed, 66 insertions(+), 1 deletion(-)
diff --git a/errors/error.go b/errors/error.go
index 53c7c7e..31b442d 100644
--- a/errors/error.go
+++ b/errors/error.go
@@ -20,7 +20,27 @@ type CustomError struct {
//implement interface error:
func (err CustomError) Error() string {
- return err.Formatted(FormattingOptions{Causes: true})
+ return err.Formatted(FormattingOptions{Causes: false})
+}
+
+func Is(e1, e2 error) bool {
+ if e1WithIs, ok := e1.(ErrorWithIs); ok {
+ return e1WithIs.Is(e2)
+ }
+ return e1.Error() == e2.Error()
+}
+
+//Is() compares the message string of this or any cause to match the specified error message
+func (err CustomError) Is(specificError error) bool {
+ if err.message == specificError.Error() {
+ return true
+ }
+ if err.cause != nil {
+ if causeWithIs, ok := err.cause.(ErrorWithIs); ok {
+ return causeWithIs.Is(specificError)
+ }
+ }
+ return false
}
//implement github.com/pkg/errors: Cause
diff --git a/errors/errors.go b/errors/errors.go
index f81e17b..8feac4f 100644
--- a/errors/errors.go
+++ b/errors/errors.go
@@ -13,6 +13,11 @@ type ErrorWithCause interface {
Code() int
}
+type ErrorWithIs interface {
+ error
+ Is(specificError error) bool
+}
+
func New(message string) error {
err := &CustomError{
message: message,
diff --git a/errors/errors_test.go b/errors/errors_test.go
index d2ce899..f9a8e2c 100644
--- a/errors/errors_test.go
+++ b/errors/errors_test.go
@@ -2,6 +2,7 @@ package errors_test
import (
"encoding/json"
+ "fmt"
"testing"
"gitlab.com/uafrica/go-utils/errors"
@@ -90,3 +91,42 @@ func f(i int) error {
}
return errors.Errorf("i=%d is odd", i)
}
+
+func TestIs(t *testing.T) {
+ //in some condition program returns
+
+ for n := 0; n <= 4; n++ {
+ if err := ReadDb(n); err != nil {
+ switch {
+ case errors.Is(err, errNotFound):
+ t.Logf("n=%d failed with NOT FOUND", n)
+ case errors.Is(err, errDisabled):
+ t.Logf("n=%d failed because disabled", n)
+ default:
+ t.Logf("n=%d failed for unknown cause: %v", n, err)
+ }
+ } else {
+ t.Logf("n=%d worked", n)
+ }
+ }
+}
+
+var (
+ errNotFound = errors.New("Not Found")
+ errDisabled = errors.New("Disabled")
+)
+
+func ReadDb(x int) error {
+ switch x {
+ case 1:
+ return errNotFound
+ case 2:
+ return errDisabled
+ case 3:
+ return nil
+ case 4:
+ return fmt.Errorf("some silly bug")
+ default:
+ return errors.Errorf("invalid x=%d", x)
+ }
+}
--
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