net/http: make ExampleGet show StatusCode checks for non-1XX,2XX responses

Updates ExampleGet to show how to handle bad responses with non-1XX,2XX
status codes. Given that the canonical examples are copied, we need
to have them properly check against failures. This is a bug I've seen
often in the wild, that's exacerbated when for example unmarshalling
JSON or even protobufs, and no errors are returned by the decoders,
so code fails silently after making a request for example to a gateway
that they were unauthorized to access.

Fixes #39778

Change-Id: I1cd688f2fab47581c8cf228235d3662b4c8e4315
Reviewed-on: https://go-review.googlesource.com/c/go/+/299609
Trust: Emmanuel Odeke <emmanuel@orijtech.com>
Run-TryBot: Emmanuel Odeke <emmanuel@orijtech.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>

diff --git a/src/net/http/example_test.go b/src/net/http/example_test.go
index c677d5223850260a70236d51e79c1241e55ac9ba..2f411d1d2ec23b3131567bc27bb9a614f08c92d0 100644 (file)
--- a/src/net/http/example_test.go
+++ b/src/net/http/example_test.go
@@ -45,12 +45,15 @@ func ExampleGet() {
        if err != nil {
                log.Fatal(err)
        }
-       robots, err := io.ReadAll(res.Body)
+       body, err := io.ReadAll(res.Body)
        res.Body.Close()
+       if res.StatusCode > 299 {
+               log.Fatalf("Response failed with status code: %d and\nbody: %s\n", res.StatusCode, body)
+       }
        if err != nil {
                log.Fatal(err)
        }
-       fmt.Printf("%s", robots)
+       fmt.Printf("%s", body)
 }
 
 func ExampleFileServer() {