net: skip unsupported tests on iOS

The new iOS test harness forwards environment variables, such that
tests that skipped on non-builders now run because GO_BUILDER_NAME
is set.

Skip the net tests that rely on resolv.conf being present.

Change-Id: I7875dc4252b2ab696c9aae13a9106ddf296ee8ec
Reviewed-on: https://go-review.googlesource.com/111476
Run-TryBot: Elias Naur <elias.naur@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>

src/net/lookup_test.go

@@ -68,6 +68,10 @@ func TestLookupGoogleSRV(t *testing.T) {
 		testenv.MustHaveExternalNetwork(t)
 	}
 
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skip("no resolv.conf on iOS")
+	}
+
 	if !supportsIPv4() || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -115,6 +119,10 @@ func TestLookupGmailMX(t *testing.T) {
 		testenv.MustHaveExternalNetwork(t)
 	}
 
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skip("no resolv.conf on iOS")
+	}
+
 	if !supportsIPv4() || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -159,6 +167,10 @@ func TestLookupGmailNS(t *testing.T) {
 		testenv.MustHaveExternalNetwork(t)
 	}
 
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skip("no resolv.conf on iOS")
+	}
+
 	if !supportsIPv4() || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -203,6 +215,10 @@ func TestLookupGmailTXT(t *testing.T) {
 		testenv.MustHaveExternalNetwork(t)
 	}
 
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skip("no resolv.conf on iOS")
+	}
+
 	if !supportsIPv4() || !*testIPv4 {
 		t.Skip("IPv4 is required")
 	}
@@ -601,6 +617,10 @@ func TestLookupDotsWithRemoteSource(t *testing.T) {
 		t.Skip("IPv4 is required")
 	}
 
+	if runtime.GOOS == "darwin" && (runtime.GOARCH == "arm" || runtime.GOARCH == "arm64") {
+		t.Skip("no resolv.conf on iOS")
+	}
+
 	defer dnsWaitGroup.Wait()
 
 	if fixup := forceGoDNS(); fixup != nil {