godev/internal/content: expect one less newline for Go 1.23

The /index.html and /index test cases happen to be testing the exact
whitespace produced by net/http's redirect body text, which lost one
of its two newlines in CL 562356. Maybe these tests shouldn't report
whitespace differences at all, but they do and such differences will
be fairly rare.

Update the test case for Go 1.23 onwards, with a small adjustment to
keep it working for older supported versions too.

Change-Id: Ia304cdb9f399f7dcb969066bf9c1ec6424b002ca
Reviewed-on: https://go-review.googlesource.com/c/telemetry/+/563357
Auto-Submit: Dmitri Shuralyov <[email protected]>
LUCI-TryBot-Result: Go LUCI <[email protected]>
Reviewed-by: Dmitri Shuralyov <[email protected]>
Reviewed-by: Robert Findley <[email protected]>

Author: dmitshur

godev/internal/content/content_test.go

@@ -6,6 +6,7 @@ package content
 
 import (
 	"errors"
+	"go/build"
 	"io/fs"
 	"net/http"
 	"net/http/httptest"
@@ -111,6 +112,10 @@ func TestServer_ServeHTTP(t *testing.T) {
 				t.Fatal(err)
 			}
 			wantBody := string(data)
+			if tt.wantCode == http.StatusMovedPermanently && len(build.Default.ReleaseTags) < 23 {
+				// Prior to Go 1.23, net/http generated an extra newline in its redirect text (CL 562356).
+				wantBody += "\n"
+			}
 			if diff := cmp.Diff(wantBody, got); diff != "" {
 				t.Errorf("GET %s response body mismatch (-want, +got):\n%s", tt.path, diff)
 			}

godev/internal/content/testdata/redirect.html.out

@@ -1,2 +1 @@
 <a href="/index">Moved Permanently</a>.
-

godev/internal/content/testdata/redirect.out

@@ -1,2 +1 @@
 <a href="/">Moved Permanently</a>.
-