net: use retry in TestLookupGmailNS

There are two flakes present on the dashboard for this test.

Change-Id: I4abec972586314fbafe7db5760b91afd7ae47fd3
Reviewed-on: https://go-review.googlesource.com/106980
Run-TryBot: Josh Bleecher Snyder <josharian@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
index 7b69bae176d4ad212046cb9130bb2b73480e0138..ab7306194f41fa7554ff1a0059a8244de3fb61e0 100644 (file)
--- a/src/net/lookup_test.go
+++ b/src/net/lookup_test.go
@@ -154,6 +154,7 @@ var lookupGmailNSTests = []struct {
 }
 
 func TestLookupGmailNS(t *testing.T) {
+       t.Parallel()
        if testenv.Builder() == "" {
                testenv.MustHaveExternalNetwork(t)
        }
@@ -162,12 +163,20 @@ func TestLookupGmailNS(t *testing.T) {
                t.Skip("IPv4 is required")
        }
 
-       defer dnsWaitGroup.Wait()
-
-       for _, tt := range lookupGmailNSTests {
+       attempts := 0
+       for i := 0; i < len(lookupGmailNSTests); i++ {
+               tt := lookupGmailNSTests[i]
                nss, err := LookupNS(tt.name)
                if err != nil {
                        testenv.SkipFlakyNet(t)
+                       if attempts < len(backoffDuration) {
+                               dur := backoffDuration[attempts]
+                               t.Logf("backoff %v after failure %v\n", dur, err)
+                               time.Sleep(dur)
+                               attempts++
+                               i--
+                               continue
+                       }
                        t.Fatal(err)
                }
                if len(nss) == 0 {