My mistake you do not need ordered just have define the times it should be called

mock.php

<?php
include 'vendor/autoload.php';

class FileObject {
    public function readBytes() { /* ... */}
}

$stub = \Mockery::mock('FileObject');

$stub->shouldReceive('readBytes')
    ->andReturn('foo')
    ->once();

$stub->shouldReceive('readBytes')
    ->once()
    ->andReturn('bar');

$stub->shouldReceive('readBytes')
    ->atLeast(1)
    ->andReturn('baz');

var_dump($stub->readBytes());
var_dump($stub->readBytes());
var_dump($stub->readBytes());
var_dump($stub->readBytes());

out.txt

string(3) "foo"
string(3) "bar"
string(3) "baz"
string(3) "baz"