Why doesn't the delete test pass?

Question

Yii

unit test. Trying to start testing (Yii2)
Made fixtures

public function _fixtures() {
        return [
            'menu' => [
                'class' => \common\fixtures\MenuFixture::className(),
                'dataFile' => codecept_data_dir() . 'menu.php'
            ]
        ];
    }

Filled out the file menu.php
Made a creation test

public function testCreateMenuItem() {
        $model = new Menu([
            'label' => 'Контакты',
            'url' => 'contacts',
            'order' => '8',
            'created_at' => '1402312317',
            'updated_at' => '1402312317',
            'delete_at' => '0',
        ]);
        $this->assertTrue($model->validate());
        $this->assertTrue($model->save());
    }

Everything seems to be ok (but as I understand it, fixtures are not involved here)
I am doing a test for deletion

public function testDeleteMenuItem() {        
        $model = Menu::findOne(1);      
        $this->assertTrue($model->delete());
    }

But it fails when running codecept --debug
Failed asserting that 1 is true.

MenuTest: Delete menu item  Destroying application
  Starting application
  [ConnectionWatcher] watching new connections
  [Fixtures] Loading fixtures
  [ConnectionWatcher] watching new connections
  [yii\db\Connection::open] 'Opening DB connection: mysql:host=localhost;dbname=may_test'
  [ConnectionWatcher] Connection opened!
  [ConnectionWatcher] Connection opened!
  [ConnectionWatcher] no longer watching new connections
  [ConnectionWatcher] closing all (1) connections
  [Fixtures] Done
  [TransactionForcer] watching new connections
  [yii\db\Connection::open] 'Opening DB connection: mysql:host=localhost;dbname=may_test'
  [ConnectionWatcher] Connection opened!
  [TransactionForcer] Connection opened!
  [TransactionForcer] Transaction started for: mysql:host=localhost;dbname=may_test
x MenuTest: Delete menu item (0.03s)
  [TransactionForcer] Transaction cancelled; all changes reverted.
  [TransactionForcer] no longer watching new connections
  Destroying application
  [ConnectionWatcher] no longer watching new connections
  [ConnectionWatcher] closing all (2) connections
  Suite done, restoring $_SERVER to original

Why doesn't it pass?