PHPUnit Mockery shouldReceive Can't find Method

I'm having problems getting mockery to find the function call with shouldReceive and getting setUp to carry the $mock variable to the test method. The class I am testing is:

<?php

class MockTester
{
    public function getOne()
    {
        return 1;
    }

    public function getTwo()
    {
        return 2;
    }
    public function getThree()
    {
        return 5;
    }enter code here
}

The test I am writing looks like:

<?php


class MockTesterTest extends TestCase
{
private $mockTester;

    public function setUp()
    {
        parent::setUp();

        $mockTester = \Mockery::mock('MockTester[getOne]');


    }

    public function tearDown()
    {
        Mockery::close();
    }


    public function testThree()
    {

        //When $mocktester is declared below I get Method getOne() from    enter code hereMockery_0_MockTester should be called, exactly 1 times but called 0 times.
        //$mockTester = \Mockery::mock('MockTester[getOne]');
        $mockTester->shouldReceive('getOne')->once();

    }

}

When $mocktester is declared in getThree I get "Method getOne() from enter code hereMockery_0_MockTester should be called, exactly 1 times but called 0 times". When it is not declared in getThree, it says Undefined variable: mockTester. When I remove set up and tear down everything runs fine.

class MockTesterTest extends TestCase
{
private $mockTester;


    public function testThree()
    {

        $mockTester = \Mockery::mock('MockTester[getOne]');
        $mockTester->shouldReceive('getOne')->once();

    }

}

I really need the set up and tear down for my project, but I keep running into this issue. I've tried protected, and public, but there is something I'm forgetting.