errors: add joinError Unwrap example

Change-Id: Id7489247e9bdd413f82fdf5a70197856c47abfb5
Reviewed-on: https://go-review.googlesource.com/c/go/+/674336
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Sean Liao <sean@liao.dev>
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
Reviewed-by: David Chase <drchase@google.com>
Auto-Submit: Sean Liao <sean@liao.dev>

diff --git a/src/errors/example_test.go b/src/errors/example_test.go
index 1976f05afa7e9fbeac0639a63f6170331c11e176..278df8c7da6e5aa7e6711ccfc9b4fa2ffdb98294 100644 (file)
--- a/src/errors/example_test.go
+++ b/src/errors/example_test.go
@@ -66,11 +66,13 @@ func ExampleJoin() {
        if errors.Is(err, err2) {
                fmt.Println("err is err2")
        }
+       fmt.Println(err.(interface{ Unwrap() []error }).Unwrap())
        // Output:
        // err1
        // err2
        // err is err1
        // err is err2
+       // [err1 err2]
 }
 
 func ExampleIs() {