godoc/redirect: add listing path for /design and add tests.

Change-Id: I05d2f48d60e433ebf1d54fb3597db580644761e1
Reviewed-on: https://go-review.googlesource.com/15282
Reviewed-by: Hyang-Ah Hana Kim <hyangah@gmail.com>
Reviewed-by: Austin Clements <austin@google.com>

godoc/redirect/redirect.go

@@ -99,6 +99,7 @@ var redirects = map[string]string{
 	"/issues":     "https://github.com/golang/go/issues",
 	"/issues/new": "https://github.com/golang/go/issues/new",
 	"/play":       "http://play.golang.org",
+	"/design":     "https://github.com/golang/proposal/tree/master/design",
 
 	// In Go 1.2 the references page is part of /doc/.
 	"/ref": "/doc/#references",

godoc/redirect/redirect_test.go

@@ -0,0 +1,99 @@
+// Copyright 2015 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package redirect
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+)
+
+type redirectResult struct {
+	status int
+	path   string
+}
+
+func errorResult(status int) redirectResult {
+	return redirectResult{status, ""}
+}
+
+func TestRedirects(t *testing.T) {
+	var tests = map[string]redirectResult{
+		"/build":    {301, "http://build.golang.org"},
+		"/ref":      {301, "/doc/#references"},
+		"/doc/mem":  {301, "/ref/mem"},
+		"/doc/spec": {301, "/ref/spec"},
+		"/tour":     {301, "http://tour.golang.org"},
+		"/foo":      errorResult(404),
+
+		"/pkg/asn1":           {301, "/pkg/encoding/asn1/"},
+		"/pkg/template/parse": {301, "/pkg/text/template/parse/"},
+
+		"/src/pkg/foo": {301, "/src/foo"},
+
+		"/cmd/gofix": {301, "/cmd/fix/"},
+
+		// git commits (/change)
+		// TODO: mercurial tags and LoadChangeMap.
+		"/change":   {301, "https://go.googlesource.com/go"},
+		"/change/a": {302, "https://go.googlesource.com/go/+/a"},
+
+		"/issue":        {301, "https://github.com/golang/go/issues"},
+		"/issues":       {301, "https://github.com/golang/go/issues"},
+		"/issue/1":      {302, "https://github.com/golang/go/issues/1"},
+		"/issues/1":     {302, "https://github.com/golang/go/issues/1"},
+		"/issue/new":    {301, "https://github.com/golang/go/issues/new"},
+		"/issues/new":   {301, "https://github.com/golang/go/issues/new"},
+		"/issues/1/2/3": errorResult(404),
+
+		"/design":              {301, "https://github.com/golang/proposal/tree/master/design"},
+		"/design/":             {302, "/design"},
+		"/design/123-foo":      {302, "https://github.com/golang/proposal/blob/master/design/123-foo.md"},
+		"/design/text/123-foo": {302, "https://github.com/golang/proposal/blob/master/design/text/123-foo.md"},
+
+		"/cl/1":          {302, "https://go-review.googlesource.com/r/1"},
+		"/cl/1/":         {302, "https://go-review.googlesource.com/r/1"},
+		"/cl/267120043":  {302, "https://codereview.appspot.com/267120043"},
+		"/cl/267120043/": {302, "https://codereview.appspot.com/267120043"},
+	}
+
+	mux := http.NewServeMux()
+	Register(mux)
+	ts := httptest.NewServer(mux)
+	defer ts.Close()
+
+	for path, want := range tests {
+		if want.path != "" && want.path[0] == '/' {
+			// All redirects are absolute.
+			want.path = ts.URL + want.path
+		}
+
+		req, err := http.NewRequest("GET", ts.URL+path, nil)
+		if err != nil {
+			t.Errorf("(path: %q) unexpected error: %v", path, err)
+			continue
+		}
+
+		resp, err := http.DefaultTransport.RoundTrip(req)
+		if err != nil {
+			t.Errorf("(path: %q) unexpected error: %v", path, err)
+			continue
+		}
+
+		if resp.StatusCode != want.status {
+			t.Errorf("(path: %q) got status %d, want %d", path, resp.StatusCode, want.status)
+		}
+
+		if want.status != 301 && want.status != 302 {
+			// Not a redirect. Just check status.
+			continue
+		}
+
+		out, _ := resp.Location()
+		if got := out.String(); got != want.path {
+			t.Errorf("(path: %q) got %s, want %s", path, got, want.path)
+		}
+	}
+}