net: mark condFatalf as a test helper

Fixes unintended consequence of CL 76393

Change-Id: I7e4644a0bc6a8b37eb41196687d9661f902ba183
Reviewed-on: https://go-review.googlesource.com/76890
Run-TryBot: Mikio Hara <mikioh.mikioh@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Alex Brainman <alex.brainman@gmail.com>

src/net/platform_test.go

@@ -149,12 +149,13 @@ func testableListenArgs(network, address, client string) bool {
 	return true
 }
 
-func condFatalf(t *testing.T, api string, format string, args ...interface{}) {
+func condFatalf(t *testing.T, network string, format string, args ...interface{}) {
+	t.Helper()
 	// A few APIs like File and Read/WriteMsg{UDP,IP} are not
 	// fully implemented yet on Plan 9 and Windows.
 	switch runtime.GOOS {
 	case "windows":
-		if api == "file" {
+		if network == "file+net" {
 			t.Logf(format, args...)
 			return
 		}

src/net/protoconn_test.go

@@ -54,7 +54,7 @@ func TestTCPListenerSpecificMethods(t *testing.T) {
 	}
 
 	if f, err := ln.File(); err != nil {
-		condFatalf(t, "file", "%v", err)
+		condFatalf(t, "file+net", "%v", err)
 	} else {
 		f.Close()
 	}
@@ -139,14 +139,14 @@ func TestUDPConnSpecificMethods(t *testing.T) {
 		t.Fatal(err)
 	}
 	if _, _, err := c.WriteMsgUDP(wb, nil, c.LocalAddr().(*UDPAddr)); err != nil {
-		condFatalf(t, "udp", "%v", err)
+		condFatalf(t, c.LocalAddr().Network(), "%v", err)
 	}
 	if _, _, _, _, err := c.ReadMsgUDP(rb, nil); err != nil {
-		condFatalf(t, "udp", "%v", err)
+		condFatalf(t, c.LocalAddr().Network(), "%v", err)
 	}
 
 	if f, err := c.File(); err != nil {
-		condFatalf(t, "file", "%v", err)
+		condFatalf(t, "file+net", "%v", err)
 	} else {
 		f.Close()
 	}
@@ -184,7 +184,7 @@ func TestIPConnSpecificMethods(t *testing.T) {
 	c.SetWriteBuffer(2048)
 
 	if f, err := c.File(); err != nil {
-		condFatalf(t, "file", "%v", err)
+		condFatalf(t, "file+net", "%v", err)
 	} else {
 		f.Close()
 	}