Move error type assertions to test file.

Per elithrar comment on PR 28:
https://github.com/gorilla/securecookie/pull/28#discussion_r35059831

2 files changed, 4 insertions, 6 deletions

diff --git a/securecookie.go b/securecookie.go
index 970f7f7..7c05972 100644
--- a/securecookie.go
+++ b/securecookie.go
@@ -88,9 +88,6 @@ func (e cookieError) Error() string {
 	return strings.Join(parts, "")
 }
 
-// Asserts that errorImpl is an Error implementation.
-var _ Error = errorImpl{}
-
 var (
 	errGeneratingIV = cookieError{typ: internalError, msg: "failed to generate random iv"}
 
@@ -591,6 +588,3 @@ func (m MultiError) any(pred func(Error) bool) bool {
 	}
 	return false
 }
-
-// Asserts that MultiError is an Error implementation.
-var _ Error = MultiError{}
diff --git a/securecookie_test.go b/securecookie_test.go
index 5778000..1d7f640 100644
--- a/securecookie_test.go
+++ b/securecookie_test.go
@@ -15,6 +15,10 @@ import (
 	"testing"
 )
 
+// Asserts that cookieError and MultiError are Error implementations.
+var _ Error = cookieError{}
+var _ Error = MultiError{}
+
 var testCookies = []interface{}{
 	map[string]string{"foo": "bar"},
 	map[string]string{"baz": "ding"},