How to mock Expression Engine global object in PHPUnit Tests when developing EE plugins

Chiko.php

<?php
//So this would be our plugin file
Class Chiko {

	public $ee;

	public function __construct()
	{
		$this->ee =& get_instance();
	}

	public function yes()
	{
		return $this->ee->addLee('Sam');
	}

}

LeeTest.php

<?php
//The file with the tests, which extends our base tests class
class LeeTest extends \TestCase {

    public function test_le()
    {
        $this->EE = \Mockery::mock('EEMock');//Create mock object, attach to our global EE
        $this->EE->shouldReceive('addLee') //Proceed as normal from here
            ->with('Sam')
            ->andReturn('SamLee');
        $chiko = new Chiko();//Won't knwow what hit it
        $this->assertEquals('SamLee', $chiko->yes('Sam'));//Profit
    }

    public function test_le2()
    {
        $this->EE = \Mockery::mock('EXE');
        $this->EE->shouldReceive('addLee')
            ->with('Sam')
            ->andReturn('SamHoio');
        $chiko = new Chiko();
        $this->assertEquals('SamHoio', $chiko->yes('Sam'));//Cleans up after itself nicely, otherwise this would fail
    }
}

TestCase.php

<?php
//Base test class
global $eeObject;//Global variable we'll be playing around with;

function get_instance()//global function to return instance of global object
{
	global $eeObject;
	return $eeObject;
}

class TestCase extends \PHPUnit_Framework_TestCase
{
    public $EE;//But we'll access global object abobe as a property of our test class, for cleanliness' sake

    public function setUp()
	  {
		  Mockery::getConfiguration()->allowMockingMethodsUnnecessarily(false);//and any other things you need to do.
		  global $eeObject;//Pull this in
		  $eeObject = null;//Clean it per run (although I think it'll be cleaned up auto)
		  $this->EE = &$eeObject;// Hook it in by ref into our test class
	  }

	public function tearDown()
	{
		global $eeObject;//clean up
		$eeObject = null;
		$this->EE = null;
		Mockery::close();
	}

}
?>