Что не так с моими тестами на PHP?

<?php

namespace Tasks\tests;

/*
require_once '../tasks/task3/Lesson.php';
require_once '../tasks/task3/Grammar.php';
require_once '../tasks/task3/Speaking.php';
require_once '../Tasks/task3/Strategy/CostStrategy.php';
require_once '../tasks/task3/Strategy/TimeStrategy.php';
require_once '../tasks/task3/Strategy/FixedStrategy.php';
*/
use Tasks\task3\Grammar;
use Tasks\task3\Speaking;
use Tasks\task3\Strategy\FixedStrategy;
use Tasks\task3\Strategy\TimeStrategy;

class TestLessons extends \PHPUnit_Framework_TestCase
{
    public function testLessonsGrammarFixedCostGood()
    {
        for ($i = 0; $i < 2; $i++) {
            $grammar = new Grammar(2, new FixedStrategy());
            $this->assertEquals(600, $grammar->cost());
        }
    }

    public function testLessonsSpeakingTimedCostGood()
    {
        for ($i = 0; $i < 2; $i++) {
            $spaeking = new Speaking(3, new TimeStrategy());
            $this->assertEquals(900, $spaeking->cost());
        }
    }

    public function testLessonsGrammarTimedCostBad()
    {
        for ($i = 0; $i < 2; $i++) {
            $grammar = new Grammar(3, new TimeStrategy());
            $this->assertNotEquals(900, $grammar->cost());
        }
    }
}