Removed dead code

message.go

@@ -6,7 +6,6 @@ package gomail
 import (
 	"bytes"
 	"io"
-	"io/ioutil"
 	"mime"
 	"os"
 	"path/filepath"
@@ -314,6 +313,3 @@ func (msg *Message) Embed(image ...*File) {
 		msg.embedded = append(msg.embedded, image...)
 	}
 }
-
-// Stubbed out for testing.
-var readFile = ioutil.ReadFile

message_test.go

@@ -191,10 +191,6 @@ func TestAlternative(t *testing.T) {
 }
 
 func TestAttachmentOnly(t *testing.T) {
-	readFile = func(filename string) ([]byte, error) {
-		return []byte("Content of " + filepath.Base(filename)), nil
-	}
-
 	msg := NewMessage()
 	msg.SetHeader("From", "from@example.com")
 	msg.SetHeader("To", "to@example.com")