From: Jonathan Amsterdam <jba@google.com>
Date: Sun, 12 Apr 2020 14:00:27 +0000 (-0400)
Subject: errors: add example for Is
X-Git-Tag: go1.15beta1~572
X-Git-Url: http://www.git.cypherpunks.su/?a=commitdiff_plain;h=7b5303d08a1b589708d6bad3d7015d9856273aac;p=gostls13.git

errors: add example for Is

Add ExampleIs to illustrate how errors.Is works.

Updates #31716.
Updates #38369.

Change-Id: I1b9a6667614635aa3a5ed8b2c108d8eb6f35748b
Reviewed-on: https://go-review.googlesource.com/c/go/+/228038
Reviewed-by: Damien Neil <dneil@google.com>
---

diff --git a/src/errors/wrap_test.go b/src/errors/wrap_test.go
index 590c1857e3..4a4a732c9b 100644
--- a/src/errors/wrap_test.go
+++ b/src/errors/wrap_test.go
@@ -238,6 +238,19 @@ func (errorUncomparable) Is(target error) bool {
 	return ok
 }
 
+func ExampleIs() {
+	if _, err := os.Open("non-existing"); err != nil {
+		if errors.Is(err, os.ErrNotExist) {
+			fmt.Println("file does not exist")
+		} else {
+			fmt.Println(err)
+		}
+	}
+
+	// Output:
+	// file does not exist
+}
+
 func ExampleAs() {
 	if _, err := os.Open("non-existing"); err != nil {
 		var pathError *os.PathError