From 155134204c034796bcd7a72c1e1b53ba005735c6 Mon Sep 17 00:00:00 2001
From: Kamil Kisiel <kamil@kamilkisiel.net>
Date: Thu, 17 Oct 2013 10:33:57 -0700
Subject: Better errors for {En,De}codeMulti.

---
 securecookie.go      | 16 ++++++++++++----
 securecookie_test.go | 13 +++++++++++++
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/securecookie.go b/securecookie.go
index 892b412..2f34bfe 100644
--- a/securecookie.go
+++ b/securecookie.go
@@ -357,12 +357,17 @@ func CodecsFromPairs(keyPairs ...[]byte) []Codec {
 	return codecs
 }
 
+var errNoCodecs = errors.New("securecookie: no codecs provided")
+
 // EncodeMulti encodes a cookie value using a group of codecs.
 //
 // The codecs are tried in order. Multiple codecs are accepted to allow
 // key rotation.
-func EncodeMulti(name string, value interface{},
-	codecs ...Codec) (string, error) {
+func EncodeMulti(name string, value interface{}, codecs ...Codec) (string, error) {
+	if len(codecs) == 0 {
+		return "", errNoCodecs
+	}
+
 	var errors MultiError
 	for _, codec := range codecs {
 		if encoded, err := codec.Encode(name, value); err == nil {
@@ -378,8 +383,11 @@ func EncodeMulti(name string, value interface{},
 //
 // The codecs are tried in order. Multiple codecs are accepted to allow
 // key rotation.
-func DecodeMulti(name string, value string, dst interface{},
-	codecs ...Codec) error {
+func DecodeMulti(name string, value string, dst interface{}, codecs ...Codec) error {
+	if len(codecs) == 0 {
+		return errNoCodecs
+	}
+
 	var errors MultiError
 	for _, codec := range codecs {
 		if err := codec.Decode(name, value, dst); err == nil {
diff --git a/securecookie_test.go b/securecookie_test.go
index 099c290..fe0cdb1 100644
--- a/securecookie_test.go
+++ b/securecookie_test.go
@@ -144,6 +144,19 @@ func TestMultiError(t *testing.T) {
 	}
 }
 
+func TestMultiNoCodecs(t *testing.T) {
+	_, err := EncodeMulti("foo", "bar")
+	if err != errNoCodecs {
+		t.Errorf("EncodeMulti: bad value for error, got: %v", err)
+	}
+
+	var dst []byte
+	err = DecodeMulti("foo", "bar", &dst)
+	if err != errNoCodecs {
+		t.Errorf("DecodeMulti: bad value for error, got: %v", err)
+	}
+}
+
 // ----------------------------------------------------------------------------
 
 type FooBar struct {
-- 
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