tstest/integration/vms: log to t.Logf directly (#2147)

Previously we used t.Logf indirectly via package log. This worked, but
it was not ideal for our needs. It could cause the streams of output to
get crossed. This change uses a logger.FuncWriter every place log.Output
was previously used, which will more correctly write log information to
the right test output stream.

Signed-off-by: Christine Dodrill <xe@tailscale.com>

tstest/integration/vms/vms_test.go

@@ -43,6 +43,7 @@ import (
 	"tailscale.com/tstest"
 	"tailscale.com/tstest/integration"
 	"tailscale.com/tstest/integration/testcontrol"
+	"tailscale.com/types/logger"
 )
 
 const (
@@ -299,8 +300,8 @@ func run(t *testing.T, dir, prog string, args ...string) {
 	tstest.FixLogs(t)
 
 	cmd := exec.Command(prog, args...)
-	cmd.Stdout = log.Writer()
-	cmd.Stderr = log.Writer()
+	cmd.Stdout = logger.FuncWriter(t.Logf)
+	cmd.Stderr = logger.FuncWriter(t.Logf)
 	cmd.Dir = dir
 	if err := cmd.Run(); err != nil {
 		t.Fatal(err)
@@ -444,8 +445,8 @@ func mkVM(t *testing.T, n int, d Distro, sshKey, hostURL, tdir string) func() {
 	t.Logf("running: qemu-system-x86_64 %s", strings.Join(args, " "))
 
 	cmd := exec.Command("qemu-system-x86_64", args...)
-	cmd.Stdout = log.Writer()
-	cmd.Stderr = log.Writer()
+	cmd.Stdout = logger.FuncWriter(t.Logf)
+	cmd.Stderr = logger.FuncWriter(t.Logf)
 	err = cmd.Start()
 
 	if err != nil {
@@ -557,9 +558,6 @@ func TestVMIntegrationEndToEnd(t *testing.T) {
 	loginServer := fmt.Sprintf("http://%s", ln.Addr())
 	t.Logf("loginServer: %s", loginServer)
 
-	tstest.FixLogs(t)
-	defer tstest.UnfixLogs(t)
-
 	ramsem := semaphore.NewWeighted(int64(*vmRamLimit))
 	bins := integration.BuildTestBinaries(t)
 
@@ -651,11 +649,11 @@ func testDistro(t *testing.T, loginServer string, d Distro, signer ssh.Signer, i
 
 	e, _, err := expect.SpawnSSH(cli, timeout,
 		expect.Verbose(true),
-		expect.VerboseWriter(log.Writer()),
+		expect.VerboseWriter(logger.FuncWriter(t.Logf)),
 
 		// // NOTE(Xe): if you get a timeout, uncomment this line to have the raw
 		// output be sent to the test log quicker.
-		//expect.Tee(nopWriteCloser{log.Writer()}),
+		//expect.Tee(nopWriteCloser{logger.FuncWriter(t.Logf)}),
 	)
 	if err != nil {
 		t.Fatalf("%d: can't register a shell session: %v", port, err)