/**
* @test
* @expectedException \InvalidArgumentException
*/
public function throws_an_exception_when_adding_a_skill_whose_name_already_exists_in_the_category()
{
$category = new Category();
$skill = (new Skill())->setTitle('foo');
$duplicate = (new Skill())->setTitle('foo');
$category->addSkill($skill);
$category->addSkill($duplicate);
}