Codeception + yii2, who will explain the truthway for working with behaviors (upload pictures), working with databases and fixtures?

Question

Software testing

A short introduction:
We have many large and medium-sized projects written in Yii2. The problem is as old as the world: testing is needed to reduce the time it takes to maintain existing applications. In tests, we only understand that they are needed like air;)
- I decided to use Codeception,
- We deployed it, made basic tests, + - I understand where everything is and why.
- I deployed the project specifically with a bug, which I try to catch but it doesn't work - the test completes successfully.
Urgent questions:
- There is a site with goods, there are labels for goods (ala action, discount, etc.) It looks like this: joxi.ru/4AkOBRPfMzdVnA On the left is a display on the site, on the right is a form for editing.
- The bug I'm trying to catch, (the picture for the sticker is required) - when editing an existing sticker, and saving it unchanged, an error is generated: "It is necessary to fill in the "Image."" Screen shot: joxi.ru/ZrJq8oLH14X04A
- The test code looks like this:

$I->amOnPage('/admin/products/site-stickers/update/5');
        $I->attachFile('#sitestickers-image', 'lace.png');
        $I->See('StickerForTest');
        $I->click('Сохранить');
        $I->dontSeeElement('.has-error');

- Test result: ✔ SiteStickersCest: Edit correct sticker (0.09s)
*The model uses behavior, didn't think of anything except debugging it (otherwise error status 0 - the file is loaded, but gives an error (apparently due to the need for further manipulations with it) )):

public function actionUpdate($id)
    {
        $model = $this->findModel($id);

        if ($model->load(Yii::$app->request->post()) && $model->validate()) {
           if (YII_ENV=='test') {
                $model->detachBehavior('photo');
            }
            $model->save( false );
            return $this->redirect(['index']);


        } else {
            return $this->render('update', [
                'model' => $model,
            ]);
        }
    }

- Tell me what I'm doing wrong?
- - The task is to cover the project not completely with tests, but to test the main critical functionality,
- - I would like to fully test the loading of the image, its further processing, writing to the model database, and checking its recording.
Thank you!

Answer 1

Colleagues, we are looking for an enthusiast who is ready to explain for $ on Skype or in an office in Moscow, the main approaches, and, for example, cover a working application with tests with my hands.