net/http: split Trailers tests into two halves

The old test was in client_test.go but was a mix of four things:

- clients writing trailers
- servers reading trailers
- servers writing trailers
- clients reading trailers

It definitely wasn't just about clients.

This moves it into clientserver_test.go and separates it into two
halves:

- servers writing trailers + clients reading trailers
- clients writing trailers + servers reading trailers

Which still isn't ideal, but is much better, and easier to read.

Updates #13557

Change-Id: I8c3e58a1f974c1b10bb11ef9b588cfa0f73ff5d9
Reviewed-on: https://go-review.googlesource.com/17895
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: Blake Mizerany <blake.mizerany@gmail.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>

src/net/http/client_test.go

@@ -20,8 +20,6 @@ import (
 	. "net/http"
 	"net/http/httptest"
 	"net/url"
-	"reflect"
-	"sort"
 	"strconv"
 	"strings"
 	"sync"
@@ -1096,81 +1094,6 @@ func (f eofReaderFunc) Read(p []byte) (n int, err error) {
 	return 0, io.EOF
 }
 
-func TestClientTrailers_h1(t *testing.T) { testClientTrailers(t, h1Mode) }
-func TestClientTrailers_h2(t *testing.T) {
-	t.Skip("skipping in http2 mode; golang.org/issue/13557")
-	testClientTrailers(t, h2Mode)
-}
-func testClientTrailers(t *testing.T, h2 bool) {
-	defer afterTest(t)
-	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
-		w.Header().Set("Connection", "close")
-		w.Header().Set("Trailer", "Server-Trailer-A, Server-Trailer-B")
-		w.Header().Add("Trailer", "Server-Trailer-C")
-
-		var decl []string
-		for k := range r.Trailer {
-			decl = append(decl, k)
-		}
-		sort.Strings(decl)
-
-		slurp, err := ioutil.ReadAll(r.Body)
-		if err != nil {
-			t.Errorf("Server reading request body: %v", err)
-		}
-		if string(slurp) != "foo" {
-			t.Errorf("Server read request body %q; want foo", slurp)
-		}
-		if r.Trailer == nil {
-			io.WriteString(w, "nil Trailer")
-		} else {
-			fmt.Fprintf(w, "decl: %v, vals: %s, %s",
-				decl,
-				r.Trailer.Get("Client-Trailer-A"),
-				r.Trailer.Get("Client-Trailer-B"))
-		}
-
-		// How handlers set Trailers: declare it ahead of time
-		// with the Trailer header, and then mutate the
-		// Header() of those values later, after the response
-		// has been written (we wrote to w above).
-		w.Header().Set("Server-Trailer-A", "valuea")
-		w.Header().Set("Server-Trailer-C", "valuec") // skipping B
-	}))
-	defer cst.close()
-
-	var req *Request
-	req, _ = NewRequest("POST", cst.ts.URL, io.MultiReader(
-		eofReaderFunc(func() {
-			req.Trailer["Client-Trailer-A"] = []string{"valuea"}
-		}),
-		strings.NewReader("foo"),
-		eofReaderFunc(func() {
-			req.Trailer["Client-Trailer-B"] = []string{"valueb"}
-		}),
-	))
-	req.Trailer = Header{
-		"Client-Trailer-A": nil, //  to be set later
-		"Client-Trailer-B": nil, //  to be set later
-	}
-	req.ContentLength = -1
-	res, err := cst.c.Do(req)
-	if err != nil {
-		t.Fatal(err)
-	}
-	if err := wantBody(res, err, "decl: [Client-Trailer-A Client-Trailer-B], vals: valuea, valueb"); err != nil {
-		t.Error(err)
-	}
-	want := Header{
-		"Server-Trailer-A": []string{"valuea"},
-		"Server-Trailer-B": nil,
-		"Server-Trailer-C": []string{"valuec"},
-	}
-	if !reflect.DeepEqual(res.Trailer, want) {
-		t.Errorf("Response trailers = %#v; want %#v", res.Trailer, want)
-	}
-}
-
 func TestReferer(t *testing.T) {
 	tests := []struct {
 		lastReq, newReq string // from -> to URLs

src/net/http/clientserver_test.go

@@ -18,6 +18,7 @@ import (
 	"net/http/httptest"
 	"os"
 	"reflect"
+	"sort"
 	"strings"
 	"sync"
 	"testing"
@@ -465,3 +466,128 @@ func testCancelRequestMidBody(t *testing.T, h2 bool) {
 		t.Errorf("ReadAll error = %v; want %v", err, ExportErrRequestCanceled)
 	}
 }
+
+// Tests that clients can send trailers to a server and that the server can read them.
+func TestTrailersClientToServer_h1(t *testing.T) { testTrailersClientToServer(t, h1Mode) }
+func TestTrailersClientToServer_h2(t *testing.T) {
+	t.Skip("skipping in http2 mode; golang.org/issue/13557")
+	testTrailersClientToServer(t, h2Mode)
+}
+
+func testTrailersClientToServer(t *testing.T, h2 bool) {
+	defer afterTest(t)
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		var decl []string
+		for k := range r.Trailer {
+			decl = append(decl, k)
+		}
+		sort.Strings(decl)
+
+		slurp, err := ioutil.ReadAll(r.Body)
+		if err != nil {
+			t.Errorf("Server reading request body: %v", err)
+		}
+		if string(slurp) != "foo" {
+			t.Errorf("Server read request body %q; want foo", slurp)
+		}
+		if r.Trailer == nil {
+			io.WriteString(w, "nil Trailer")
+		} else {
+			fmt.Fprintf(w, "decl: %v, vals: %s, %s",
+				decl,
+				r.Trailer.Get("Client-Trailer-A"),
+				r.Trailer.Get("Client-Trailer-B"))
+		}
+	}))
+	defer cst.close()
+
+	var req *Request
+	req, _ = NewRequest("POST", cst.ts.URL, io.MultiReader(
+		eofReaderFunc(func() {
+			req.Trailer["Client-Trailer-A"] = []string{"valuea"}
+		}),
+		strings.NewReader("foo"),
+		eofReaderFunc(func() {
+			req.Trailer["Client-Trailer-B"] = []string{"valueb"}
+		}),
+	))
+	req.Trailer = Header{
+		"Client-Trailer-A": nil, //  to be set later
+		"Client-Trailer-B": nil, //  to be set later
+	}
+	req.ContentLength = -1
+	res, err := cst.c.Do(req)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if err := wantBody(res, err, "decl: [Client-Trailer-A Client-Trailer-B], vals: valuea, valueb"); err != nil {
+		t.Error(err)
+	}
+}
+
+// Tests that servers send trailers to a client and that the client can read them.
+func TestTrailersServerToClient_h1(t *testing.T) { testTrailersServerToClient(t, h1Mode, false) }
+func TestTrailersServerToClient_h2(t *testing.T) {
+	t.Skip("skipping in http2 mode; golang.org/issue/13557")
+	testTrailersServerToClient(t, h2Mode, false)
+}
+func TestTrailersServerToClient_Flush_h1(t *testing.T) { testTrailersServerToClient(t, h1Mode, true) }
+func TestTrailersServerToClient_Flush_h2(t *testing.T) {
+	t.Skip("skipping in http2 mode; golang.org/issue/13557")
+	testTrailersServerToClient(t, h2Mode, true)
+}
+
+func testTrailersServerToClient(t *testing.T, h2, flush bool) {
+	defer afterTest(t)
+	const body = "Some body"
+	cst := newClientServerTest(t, h2, HandlerFunc(func(w ResponseWriter, r *Request) {
+		w.Header().Set("Trailer", "Server-Trailer-A, Server-Trailer-B")
+		w.Header().Add("Trailer", "Server-Trailer-C")
+
+		io.WriteString(w, body)
+		if flush {
+			w.(Flusher).Flush()
+		}
+
+		// How handlers set Trailers: declare it ahead of time
+		// with the Trailer header, and then mutate the
+		// Header() of those values later, after the response
+		// has been written (we wrote to w above).
+		w.Header().Set("Server-Trailer-A", "valuea")
+		w.Header().Set("Server-Trailer-C", "valuec") // skipping B
+		w.Header().Set("Server-Trailer-NotDeclared", "should be omitted")
+	}))
+	defer cst.close()
+
+	res, err := cst.c.Get(cst.ts.URL)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	delete(res.Header, "Date") // irrelevant for test
+	if got, want := res.Header, (Header{
+		"Content-Type": {"text/plain; charset=utf-8"},
+	}); !reflect.DeepEqual(got, want) {
+		t.Errorf("Header = %v; want %v", got, want)
+	}
+
+	if got, want := res.Trailer, (Header{
+		"Server-Trailer-A": nil,
+		"Server-Trailer-B": nil,
+		"Server-Trailer-C": nil,
+	}); !reflect.DeepEqual(got, want) {
+		t.Errorf("Trailer before body read = %v; want %v", got, want)
+	}
+
+	if err := wantBody(res, nil, body); err != nil {
+		t.Fatal(err)
+	}
+
+	if got, want := res.Trailer, (Header{
+		"Server-Trailer-A": {"valuea"},
+		"Server-Trailer-B": nil,
+		"Server-Trailer-C": {"valuec"},
+	}); !reflect.DeepEqual(got, want) {
+		t.Errorf("Trailer after body read = %v; want %v", got, want)
+	}
+}

src/net/http/transfer.go

@@ -577,21 +577,29 @@ func shouldClose(major, minor int, header Header, removeCloseHeader bool) bool {
 
 // Parse the trailer header
 func fixTrailer(header Header, te []string) (Header, error) {
-	raw := header.get("Trailer")
-	if raw == "" {
+	vv, ok := header["Trailer"]
+	if !ok {
 		return nil, nil
 	}
-
 	header.Del("Trailer")
+
 	trailer := make(Header)
-	keys := strings.Split(raw, ",")
-	for _, key := range keys {
-		key = CanonicalHeaderKey(strings.TrimSpace(key))
-		switch key {
-		case "Transfer-Encoding", "Trailer", "Content-Length":
-			return nil, &badStringError{"bad trailer key", key}
-		}
-		trailer[key] = nil
+	var err error
+	for _, v := range vv {
+		foreachHeaderElement(v, func(key string) {
+			key = CanonicalHeaderKey(key)
+			switch key {
+			case "Transfer-Encoding", "Trailer", "Content-Length":
+				if err == nil {
+					err = &badStringError{"bad trailer key", key}
+					return
+				}
+			}
+			trailer[key] = nil
+		})
+	}
+	if err != nil {
+		return nil, err
 	}
 	if len(trailer) == 0 {
 		return nil, nil