From 1fe0983f2d016b525e0d33e76631e333efefb466 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <bradfitz@tailscale.com>
Date: Fri, 3 May 2024 06:29:35 -0700
Subject: [PATCH] cmd/derper,tstest/nettest: skip network-needing test in
 airplane mode

Not buying wifi on a short flight is a good way to find tests
that require network. Whoops.

Updates #cleanup

Change-Id: Ibe678e9c755d27269ad7206413ffe9971f07d298
Signed-off-by: Brad Fitzpatrick <bradfitz@tailscale.com>
---
 cmd/derper/bootstrap_dns_test.go |  3 +++
 tstest/nettest/nettest.go        | 21 +++++++++++++++++++++
 2 files changed, 24 insertions(+)
 create mode 100644 tstest/nettest/nettest.go

diff --git a/cmd/derper/bootstrap_dns_test.go b/cmd/derper/bootstrap_dns_test.go
index bd6786558..0a4496f61 100644
--- a/cmd/derper/bootstrap_dns_test.go
+++ b/cmd/derper/bootstrap_dns_test.go
@@ -13,6 +13,7 @@
 	"testing"
 
 	"tailscale.com/tstest"
+	"tailscale.com/tstest/nettest"
 )
 
 func BenchmarkHandleBootstrapDNS(b *testing.B) {
@@ -55,6 +56,8 @@ func getBootstrapDNS(t *testing.T, q string) dnsEntryMap {
 }
 
 func TestUnpublishedDNS(t *testing.T) {
+	nettest.SkipIfNoNetwork(t)
+
 	const published = "login.tailscale.com"
 	const unpublished = "log.tailscale.io"
 
diff --git a/tstest/nettest/nettest.go b/tstest/nettest/nettest.go
new file mode 100644
index 000000000..47c8857a5
--- /dev/null
+++ b/tstest/nettest/nettest.go
@@ -0,0 +1,21 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+// Package nettest contains additional test helpers related to network state
+// that can't go into tstest for circular dependency reasons.
+package nettest
+
+import (
+	"testing"
+
+	"tailscale.com/net/netmon"
+)
+
+// SkipIfNoNetwork skips the test if it looks like there's no network
+// access.
+func SkipIfNoNetwork(t testing.TB) {
+	nm := netmon.NewStatic()
+	if !nm.InterfaceState().AnyInterfaceUp() {
+		t.Skip("skipping; test requires network but no interface is up")
+	}
+}