Mofu.php

<?php
abstract class Mofu {
    abstract protected function isNyan();

    public function mofureyo() {
        if($this->isNyan() === true) {
            return "mofure";
        } else {
            return "mofuruna";
        }
    }
}

trait Nyan {
    protected function isNyan() {
        return true;
    }
}

class MofuImpl extends Mofu {
    use Nyan;
}

echo "普通のコード\n";
$mofu = new MofuImpl();
echo $mofu->mofureyo()."\n";

trait MockNyan {
    protected function isNyan() {
        return false;
    }
}

class MockMofuImpl extends Mofu {
    use MockNyan;
}

echo "テストコード\n";
$mofu = new MockMofuImpl();
echo $mofu->mofureyo()."\n";