Error: Fatal Error (1): Class 'AppShell' not found in when testing the cake2.x shell with PHPUnit

Error: Fatal Error (1): Class 'AppShell' not found in
Error: [FatalErrorException] Class 'AppShell' not found

App::uses('ComponentCollection', 'Controller');
App::uses('TestCommonComponent', 'Controller/Component');
class TestShell extensions AppShell {
    public$uses=array(
        'TestModel 1',
        'TestModel 2'
   );
   public function startup() {
       parent::startup();
   }

    public function main() {

<?php
App::uses('ConsoleOutput','Console');
App::uses('ShellDispatcher', 'Console');
App::uses('Shell', 'Console');
App::uses('Folder', 'Utility');
App::uses('TestShell', 'Console/Command');

class TestShellTest extensions CakeTestCase {
    public$target;
    public function setUp(){
        parent::setUp();

        $output=$this->getMock('ConsoleOutput', array(), array(), '', false);
        $error=$this->getMock('ConsoleOutput', array(), array(), '', false);
        $in = $this->getMock('ConsoleInput', array(), array(), '', false);
        $this->target=new TestShell($output,$error,$in);
        $this->target->initialize();
    }

    public function tearDown(){
        parent::tearDown();
    }

    public function testCommon() {
// Write a test here
        $this->assertEquals(0,0);
    }
}