Allow sudofn injection into connection (#227)

- allow connection objects to have a sudofn injected
- if sudofn is set, then Connect won't try to detect it

Signed-off-by: James Nesbitt <jnesbitt@mirantis.com>

connection.go

@@ -241,11 +241,19 @@ func (c *Connection) Connect() error {
 		c.OSVersion = &o
 	}
 
-	c.configureSudo()
+	if c.sudofunc == nil {
+		c.discoverSudo()
+	}
 
 	return nil
 }
 
+// SetSudofn inject a sudofn into the connection before Connect()
+// @NOTE this will avoid sudo detection if done before Connect()
+func (c *Connection) SetSudofn(f func(string) string) {
+	c.sudofunc = f
+}
+
 func sudoNoop(cmd string) string {
 	return cmd
 }
@@ -287,21 +295,21 @@ func sudoWindows(cmd string) string {
 	return cmd
 }
 
-func (c *Connection) configureSudo() {
+func (c *Connection) discoverSudo() {
 	if !c.IsWindows() {
 		if c.Exec(`[ "$(id -u)" = 0 ]`) == nil {
 			// user is already root
-			c.sudofunc = sudoNoop
+			c.SetSudofn(sudoNoop)
 			return
 		}
 		if c.Exec(`sudo -n -l`) == nil {
 			// user has passwordless sudo
-			c.sudofunc = sudoSudo
+			c.SetSudofn(sudoSudo)
 			return
 		}
 		if c.Exec(`doas -n -- "${SHELL-sh}" -c true`) == nil {
 			// user has passwordless doas
-			c.sudofunc = sudoDoas
+			c.SetSudofn(sudoDoas)
 		}
 		return
 	}