net: don't recheck goosPrefersCgo in hostLookupOrder

We only did it for testing. Remove the single test that required it.

Change-Id: Ib6c3a2debfd3f48e95af37f23fdfde847ff87a41
Reviewed-on: https://go-review.googlesource.com/c/go/+/490395
Run-TryBot: Ian Lance Taylor <[email protected]>
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Bryan Mills <[email protected]>
Reviewed-by: Damien Neil <[email protected]>
Auto-Submit: Ian Lance Taylor <[email protected]>

Author: ianlancetaylor

src/net/conf.go

@@ -124,7 +124,7 @@ func initConfVal() {
 	}
 
 	// Some operating systems always prefer the cgo resolver.
-	if goosPrefersCgo(runtime.GOOS) {
+	if goosPrefersCgo() {
 		confVal.preferCgo = true
 		return
 	}
@@ -155,8 +155,8 @@ func initConfVal() {
 
 // goosPreferCgo reports whether the GOOS value passed in prefers
 // the cgo resolver.
-func goosPrefersCgo(goos string) bool {
-	switch goos {
+func goosPrefersCgo() bool {
+	switch runtime.GOOS {
 	// Historically on Windows and Plan 9 we prefer the
 	// cgo resolver (which doesn't use the cgo tool) rather than
 	// the go resolver. This is because originally these
@@ -227,13 +227,6 @@ func (c *conf) hostLookupOrder(r *Resolver, hostname string) (ret hostLookupOrde
 		// Neither resolver was explicitly requested
 		// and we have no preference.
 
-		// For testing purposes only, recheck the GOOS.
-		// This lets TestConfHostLookupOrder test different
-		// GOOS values.
-		if goosPrefersCgo(c.goos) {
-			return hostLookupCgo, nil
-		}
-
 		if bytealg.IndexByteString(hostname, '\\') != -1 || bytealg.IndexByteString(hostname, '%') != -1 {
 			// Don't deal with special form hostnames
 			// with backslashes or '%'.

src/net/conf_test.go

@@ -341,18 +341,6 @@ func TestConfHostLookupOrder(t *testing.T) {
 			nss:       nssStr(t, "foo: bar"),
 			hostTests: []nssHostTest{{"google.com", "myhostname", hostLookupCgo}},
 		},
-		// Android should always use cgo.
-		{
-			name: "android",
-			c: &conf{
-				goos: "android",
-			},
-			resolv: defaultResolvConf,
-			nss:    nssStr(t, ""),
-			hostTests: []nssHostTest{
-				{"x.com", "myhostname", hostLookupCgo},
-			},
-		},
 		// Issue 24393: make sure "Resolver.PreferGo = true" acts like netgo.
 		{
 			name:     "resolver-prefergo",