encoding/json: implement Is on SyntaxError
Allows users to check:
errors.Is(err, &json.SyntaxError{})
which is the recommended way of checking for kinds of errors.
Change-Id: I20dc805f20212765e9936a82d9cb7822e73ec4ef
GitHub-Last-Rev: e2627ccf8e2a00cc3459bb9fee86c3c8675a33af
GitHub-Pull-Request: golang/go#41210
Reviewed-on: https://go-review.googlesource.com/c/go/+/253037
Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/src/encoding/json/scanner.go b/src/encoding/json/scanner.go
index 9dc1903..05218f9 100644
--- a/src/encoding/json/scanner.go
+++ b/src/encoding/json/scanner.go
@@ -49,6 +49,12 @@
func (e *SyntaxError) Error() string { return e.msg }
+// Is returns true if target is a SyntaxError.
+func (e *SyntaxError) Is(target error) bool {
+ _, ok := target.(*SyntaxError)
+ return ok
+}
+
// A scanner is a JSON scanning state machine.
// Callers call scan.reset and then pass bytes in one at a time
// by calling scan.step(&scan, c) for each byte.
diff --git a/src/encoding/json/scanner_test.go b/src/encoding/json/scanner_test.go
index 3737516..c12d9bf 100644
--- a/src/encoding/json/scanner_test.go
+++ b/src/encoding/json/scanner_test.go
@@ -6,6 +6,8 @@
import (
"bytes"
+ "errors"
+ "fmt"
"math"
"math/rand"
"reflect"
@@ -201,6 +203,13 @@
}
}
+func TestSyntaxErrorIs(t *testing.T) {
+ err := fmt.Errorf("apackage: %w: failed to parse struct", &SyntaxError{"some error", 43})
+ if !errors.Is(err, &SyntaxError{}) {
+ t.Fatalf("%v should be unwrapped to a SyntaxError", err)
+ }
+}
+
func diff(t *testing.T, a, b []byte) {
for i := 0; ; i++ {
if i >= len(a) || i >= len(b) || a[i] != b[i] {
