net/http: speed up tests, use t.Parallel when it's safe

Before: 8.9 seconds for go test -short
 After: 2.8 seconds

There are still 250 tests without t.Parallel, but I got the important
onces using a script:

    $ go test -short -v 2>&1 | go run ~/slowtests.go

Where slowtests.go is https://play.golang.org/p/9mh5Wg1nLN

The remaining 250 (the output lines from slowtests.go) all have a
reported duration of 0ms, except one 50ms test which has to be serial.

Where tests can't be parallel, I left a comment at the top saying why,
so people don't add t.Parallel later and get surprised at failures.

Updates #17751

Change-Id: Icbe32cbe2b996e23c89f1af6339287fa22af5115
Reviewed-on: https://go-review.googlesource.com/32684
Run-TryBot: Brad Fitzpatrick <[email protected]>
TryBot-Result: Gobot Gobot <[email protected]>
Reviewed-by: Josh Bleecher Snyder <[email protected]>

src/net/http/client_test.go

@@ -197,6 +197,7 @@ func TestPostFormRequestFormat(t *testing.T) {
 }
 
 func TestClientRedirects(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	var ts *httptest.Server
 	ts = httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
@@ -294,6 +295,7 @@ func TestClientRedirects(t *testing.T) {
 }
 
 func TestClientRedirectContext(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
 		Redirect(w, r, "/", StatusTemporaryRedirect)
@@ -462,6 +464,7 @@ func testRedirectsByMethod(t *testing.T, method string, table []redirectTest, wa
 }
 
 func TestClientRedirectUseResponse(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	const body = "Hello, world."
 	var ts *httptest.Server
@@ -811,6 +814,7 @@ func TestClientWrites(t *testing.T) {
 }
 
 func TestClientInsecureTransport(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	ts := httptest.NewTLSServer(HandlerFunc(func(w ResponseWriter, r *Request) {
 		w.Write([]byte("Hello"))
@@ -1269,6 +1273,7 @@ func testClientTimeout_Headers(t *testing.T, h2 bool) {
 func TestClientRedirectEatsBody_h1(t *testing.T) { testClientRedirectEatsBody(t, h1Mode) }
 func TestClientRedirectEatsBody_h2(t *testing.T) { testClientRedirectEatsBody(t, h2Mode) }
 func testClientRedirectEatsBody(t *testing.T, h2 bool) {
+	setParallel(t)
 	defer afterTest(t)
 	saw := make(chan string, 2)
 	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
@@ -1580,6 +1585,7 @@ func TestShouldCopyHeaderOnRedirect(t *testing.T) {
 }
 
 func TestClientRedirectTypes(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 
 	tests := [...]struct {

src/net/http/clientserver_test.go

@@ -170,6 +170,7 @@ func (tt h12Compare) reqFunc() reqFunc {
 }
 
 func (tt h12Compare) run(t *testing.T) {
+	setParallel(t)
 	cst1 := newClientServerTest(t, false, HandlerFunc(tt.Handler), tt.Opts...)
 	defer cst1.close()
 	cst2 := newClientServerTest(t, true, HandlerFunc(tt.Handler), tt.Opts...)
@@ -938,6 +939,7 @@ func testStarRequest(t *testing.T, method string, h2 bool) {
 
 // Issue 13957
 func TestTransportDiscardsUnneededConns(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	cst := newClientServerTest(t, h2Mode, HandlerFunc(func(w ResponseWriter, r *Request) {
 		fmt.Fprintf(w, "Hello, %v", r.RemoteAddr)
@@ -1022,6 +1024,7 @@ func TestTransportGCRequest_Body_h2(t *testing.T)   { testTransportGCRequest(t,
 func TestTransportGCRequest_NoBody_h1(t *testing.T) { testTransportGCRequest(t, h1Mode, false) }
 func TestTransportGCRequest_NoBody_h2(t *testing.T) { testTransportGCRequest(t, h2Mode, false) }
 func testTransportGCRequest(t *testing.T, h2, body bool) {
+	setParallel(t)
 	defer afterTest(t)
 	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
 		ioutil.ReadAll(r.Body)
@@ -1068,6 +1071,7 @@ func TestTransportRejectsInvalidHeaders_h2(t *testing.T) {
 	testTransportRejectsInvalidHeaders(t, h2Mode)
 }
 func testTransportRejectsInvalidHeaders(t *testing.T, h2 bool) {
+	setParallel(t)
 	defer afterTest(t)
 	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
 		fmt.Fprintf(w, "Handler saw headers: %q", r.Header)
@@ -1200,6 +1204,7 @@ func TestH12_AutoGzipWithDumpResponse(t *testing.T) {
 func TestCloseIdleConnections_h1(t *testing.T) { testCloseIdleConnections(t, h1Mode) }
 func TestCloseIdleConnections_h2(t *testing.T) { testCloseIdleConnections(t, h2Mode) }
 func testCloseIdleConnections(t *testing.T, h2 bool) {
+	setParallel(t)
 	defer afterTest(t)
 	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
 		w.Header().Set("X-Addr", r.RemoteAddr)

src/net/http/fs_test.go

@@ -68,6 +68,7 @@ var ServeFileRangeTests = []struct {
 }
 
 func TestServeFile(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	ts := httptest.NewServer(HandlerFunc(func(w ResponseWriter, r *Request) {
 		ServeFile(w, r, "testdata/file")
@@ -1064,6 +1065,7 @@ func TestServeContentErrorMessages(t *testing.T) {
 
 // verifies that sendfile is being used on Linux
 func TestLinuxSendfile(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	if runtime.GOOS != "linux" {
 		t.Skip("skipping; linux-only test")

src/net/http/http_test.go

@@ -82,6 +82,7 @@ func TestCleanHost(t *testing.T) {
 // This catches accidental dependencies between the HTTP transport and
 // server code.
 func TestCmdGoNoHTTPServer(t *testing.T) {
+	t.Parallel()
 	goBin := testenv.GoToolPath(t)
 	out, err := exec.Command(goBin, "tool", "nm", goBin).CombinedOutput()
 	if err != nil {

src/net/http/npn_test.go

@@ -18,6 +18,7 @@ import (
 )
 
 func TestNextProtoUpgrade(t *testing.T) {
+	setParallel(t)
 	defer afterTest(t)
 	ts := httptest.NewUnstartedServer(HandlerFunc(func(w ResponseWriter, r *Request) {
 		fmt.Fprintf(w, "path=%s,proto=", r.URL.Path)

src/net/http/response_test.go

@@ -589,6 +589,7 @@ var readResponseCloseInMiddleTests = []struct {
 // reading only part of its contents advances the read to the end of
 // the request, right up until the next request.
 func TestReadResponseCloseInMiddle(t *testing.T) {
+	t.Parallel()
 	for _, test := range readResponseCloseInMiddleTests {
 		fatalf := func(format string, args ...interface{}) {
 			args = append([]interface{}{test.chunked, test.compressed}, args...)