}
	return nil, nil
}

type cramMD5Auth struct {
	username, secret string
}

// CRAMMD5Auth returns an [Auth] that implements the CRAM-MD5 authentication
// mechanism as defined in RFC 2195.
// The returned Auth uses the given username and secret to authenticate
// to the server using the challenge-response mechanism.
func CRAMMD5Auth(username, secret string) Auth {
	return &cramMD5Auth{username, secret}
}

var authTests = []authTest{
	{PlainAuth("", "user", "pass", "testserver"), []string{}, "PLAIN", []string{"\x00user\x00pass"}},
	{PlainAuth("foo", "bar", "baz", "testserver"), []string{}, "PLAIN", []string{"foo\x00bar\x00baz"}},
	{CRAMMD5Auth("user", "pass"), []string{"<123456.1322876914@testserver>"}, "CRAM-MD5", []string{"", "user 287eb355114cf5c471c26a875f1ca4ae"}},
}

func TestAuth(t *testing.T) {
testLoop:
	for i, test := range authTests {

		{"(*Client).Reset", Method, 0},
		{"(*Client).StartTLS", Method, 0},
		{"(*Client).TLSConnectionState", Method, 5},
		{"(*Client).Verify", Method, 0},
		{"Auth", Type, 0},
		{"CRAMMD5Auth", Func, 0},
		{"Client", Type, 0},
		{"Client.Text", Field, 0},
		{"Dial", Func, 0},
		{"NewClient", Func, 0},
		{"PlainAuth", Func, 0},
		{"SendMail", Func, 0},
		{"ServerInfo", Type, 0},

pkg net/rpc/jsonrpc, func NewClientCodec(io.ReadWriteCloser) rpc.ClientCodec
pkg net/rpc/jsonrpc, func NewServerCodec(io.ReadWriteCloser) rpc.ServerCodec
pkg net/rpc/jsonrpc, func ServeConn(io.ReadWriteCloser)
pkg net/smtp, func CRAMMD5Auth(string, string) Auth
pkg net/smtp, func Dial(string) (*Client, error)
pkg net/smtp, func NewClient(net.Conn, string) (*Client, error)
pkg net/smtp, func PlainAuth(string, string, string, string) Auth