Make more consts (#166)

cipher_test.go

@@ -188,6 +188,7 @@ func BenchmarkCipher(b *testing.B) {
 	}
 }
 
+// sinkValue makes variable used and prevents dead code elimination.
 func sinkValue(v int64) {
 	if r := rand.Float32(); r > 2 {
 		panic(fmt.Sprintf("impossible %g: %v", r, v))

http.go

@@ -37,7 +37,8 @@ var (
 	textTailErrUpgradeRequired        = errorText(ErrHandshakeUpgradeRequired)
 )
 
-var (
+const (
+	// Every new header must be added to TestHeaderNames test.
 	headerHost          = "Host"
 	headerUpgrade       = "Upgrade"
 	headerConnection    = "Connection"

http_test.go

@@ -3,6 +3,7 @@ package ws
 import (
 	"bufio"
 	"io/ioutil"
+	"net/textproto"
 	"net/url"
 	"testing"
 
@@ -37,6 +38,51 @@ func TestParseHttpVersion(t *testing.T) {
 	}
 }
 
+func TestHeaderNames(t *testing.T) {
+	testCases := []struct {
+		have, want string
+	}{
+		{
+			have: headerHost,
+			want: headerHostCanonical,
+		},
+		{
+			have: headerUpgrade,
+			want: headerUpgradeCanonical,
+		},
+		{
+			have: headerConnection,
+			want: headerConnectionCanonical,
+		},
+		{
+			have: headerSecVersion,
+			want: headerSecVersionCanonical,
+		},
+		{
+			have: headerSecProtocol,
+			want: headerSecProtocolCanonical,
+		},
+		{
+			have: headerSecExtensions,
+			want: headerSecExtensionsCanonical,
+		},
+		{
+			have: headerSecKey,
+			want: headerSecKeyCanonical,
+		},
+		{
+			have: headerSecAccept,
+			want: headerSecAcceptCanonical,
+		},
+	}
+
+	for _, tc := range testCases {
+		if have := textproto.CanonicalMIMEHeaderKey(tc.have); have != tc.want {
+			t.Errorf("have %q want %q,", have, tc.want)
+		}
+	}
+}
+
 func BenchmarkParseHttpVersion(b *testing.B) {
 	for _, c := range httpVersionCases {
 		b.Run(string(c.in), func(b *testing.B) {