Writing testable Code (MageTitans Mini 2016)

WRITING
TESTABLE
CODEWriting Testable Code - MageTitans Mini, 5th May 2016 - ! - contact@vinaikopp.com - twitter://@VinaiKopp

Vinai Kopp
Freelance Developer & Trainer
Tweet me @VinaiKopp
Writing Testable Code - MageTitans Mini, 5th May 2016 - ! - contact@vinaikopp.com - twitter://@VinaiKopp

I want to get into testing

" WANT TO "
"I have to GET INTO TESTING"

CHOOSE A TOOL +
LEARN THE SYNTAX

▸ PHPUnit
▸ PHPSpec
▸ Codeception
▸ nvm...

That wasn't so bad!

Current status:
A metric ton of untested legacy code

Start with writing tests for bugs

THIS IS HARD

This costs lots of time!

This is painful!

There has to be
a better way...!

<?php
/**
* @todo make more testable
*

Things to keep in mind
to write TESTABLE CODE

KEEP CLASSES
SMALLWriting Testable Code - MageTitans Mini, 5th May 2016 - ! - contact@vinaikopp.com - twitter://@VinaiKopp

A bad example:
Event Observer
(for Magento 1)

<?php
use Varien_Event_Observer as Event;
class Netzarbeiter_CustomerActivation_Model_Observer
{
// Check if the customer has been activated, if not, throw login error
public function customerLogin(Event $event) {...}
// Flag new accounts as such
public function customerSaveBefore(Event $event) {...}
// Send out emails
public function customerSaveAfter(Event $event) {...}
// Abort registration during checkout if default activation status is false
public function salesConvertQuoteAddressToOrder(Event $event) {...}
// Add customer activation option to the mass action block
public function adminhtmlBlockHtmlBefore(Event $event) {...}
// Add the customer_activated attribute to the customer grid collection
public function eavCollectionAbstractLoadBefore(Event $event) {...}
// Add customer_activated column to CSV and XML exports
public function coreBlockAbstractPrepareLayoutAfter(Event $event) {...}
// Remove the customer id from the customer/session, in effect causing a logout just in case
public function controllerActionPostdispatchCustomerAccountResetPasswordPost(Event $event) {...}
}

SMALLER?
HOW?

First attempt:

WHAT DOES IT DO?

1. Prevent inactive customer logins
2. Send notification emails
3. Add column to customer grid

split
Netzarbeiter_CustomerActivation_Model_Observer
into
..._Model_Observer_ProhibitInactiveLogins
..._Model_Observer_EmailNotifications
..._Model_Observer_AdminhtmlCustomerGrid

<?php
class Netzarbeiter_CustomerActivation_Model_Observer_ProhibitInactiveLogin
{
// Check if the customer has been activated, if not, throw login error
public function customerLogin(Event $event) {...}
// Abort registration during checkout if default activation status is false
public function salesConvertQuoteAddressToOrder(Event $event) {...}
// Remove the customer id from the customer/session, in effect causing a logout just in case
public function controllerActionPostdispatchCustomerAccountResetPasswordPost(Event $event) {...}
}

<?php
class Netzarbeiter_CustomerActivation_Model_Observer_EmailNotifications
{
// Flag new accounts as such
public function customerSaveBefore(Event $event) {...}
// Send out emails
public function customerSaveAfter(Event $event) {...}
}

<?php
class Netzarbeiter_CustomerActivation_Model_Observer_AdminhtmlCustomerGrid
{
// Add customer activation option to the mass action block
public function adminhtmlBlockHtmlBefore(Event $event) {...}
// Add the customer_activated attribute to the customer grid collection
public function eavCollectionAbstractLoadBefore(Event $event) {...}
// Add customer_activated column to CSV and XML exports
public function coreBlockAbstractPrepareLayoutAfter(Event $event) {...}
}

Pretty rough...

Okay first step

MINOR DIFFERENCE IN
TESTING EFFORT

Second attempt:

Look closer

Dependencies:
Netzarbeiter_CustomerActivation_Helper_Data
Mage_Customer_Model_Customer
Mage_Customer_Model_Session
Mage_Customer_Model_Group
Mage_Customer_Helper_Address
Mage_Customer_Model_Resource_Customer_Collection
Mage_Core_Controller_Request_Http
Mage_Core_Controller_Response_Http
Mage_Core_Exception
Mage_Core_Model_Session
Mage_Core_Model_Store
Mage_Sales_Model_Quote_Address
Mage_Sales_Model_Quote
Mage_Eav_Model_Config
Mage_Eav_Model_Entity_Type
Mage_Adminhtml_Block_Widget_Grid_Massaction
Mage_Adminhtml_Block_Widget_Grid

Business logic is hidden in Observer or Helper
Netzarbeiter_CustomerActivation_Model_Observer
Netzarbeiter_CustomerActivation_Helper_Data

Observers link
Business logic
!
Magento

Old Code:

public function customerLogin($observer)
{
$helper = Mage::helper('customeractivation');
if (!$helper->isModuleActive()) {
return;
}
if ($this->_isApiRequest()) {
return;
}
$customer = $observer->getEvent()->getCustomer();
$session = Mage::getSingleton('customer/session');
if (!$customer->getCustomerActivated()) {
$session->setCustomer(Mage::getModel('customer/customer'))
->setId(null)
->setCustomerGroupId(Mage_Customer_Model_Group::NOT_LOGGED_IN_ID);
if ($this->_checkRequestRoute('customer', 'account', 'createpost')) {
$message = $helper->__('Please wait for your account to be activated');
$session->addSuccess($message);
} else {
Mage::throwException($helper->__('This account is not activated.'));
}
}
}

New Code:

public function customerLogin(Event $event)
{
if (! $this->isModuleActive()) {
return;
}
$this->getCustomerLoginSentry()->abortLoginIfNotActive(
$event->getData('customer')
);
}

▸ Details are hidden
▸ Delegation
▸ No magic getters

private static $sentry = 'customeractivation/customerLoginSentry';
/**
* @return Netzarbeiter_CustomerActivation_Model_CustomerLoginSentry
*/
private function getCustomerLoginSentry()
{
return isset($this->loginSentry) ?
$this->loginSentry :
Mage::getModel(self::$sentry);
}

▸ Dependencies can be injected
▸ Business logic moved into model

Model with specific responsibility
class Netzarbeiter_CustomerActivation_Model_CustomerLoginSentry

public function abortLoginIfNotActive(Mage_Customer_Model_Customer $customer)
{
if (! $customer->getData('customer_activated') {
$this->getSession()->logout();
$this->getDisplay()->showLoginAbortedMessage();
}
}

▸ Business logic independent of entry point
▸ More type safety

private function getSession()
{
return isset($this->session) ?
$this->session :
Mage::getModel('customeractivation/session');
}
private function getDisplay()
{
return isset($this->display) ?
$this->display :
Mage::getModel('customeractivation/display');
}

▸ Injectable dependencies
▸ Business logic in specific models

Need something done?
Need some information?

"I don't care how it's done!"

Delegate!

IDCDD

I Don't Care Driven Development

I Don't Care Driven Design

The result?

CLASS EXPLOSION!

SMALL CLASSES

TrivialTO TEST

How far can delegation go?

Delegate until the next
delegator == delegatee

In the end
our class
is wrapping
a Magento class

In the end
our class
is wrapping
a Framework class

DECOUPLING FROM
THE FRAMEWORK

This is a Good Thing

ONE
FAQWHEN STARTING WITH TESTING

WHAT TO
TEST?

Better question:

WHY DOES
THE CLASS EXIST?

WHY DOES
THE METHOD EXIST?

RETURN A VALUE
OR
SIDE EFFECT

If a method
RETURNS A VALUE
only test for that

If a method
CAUSES A SIDE EFFECT
only test for that

SIDE EFFECTS?

Side Effect #1:
Global State

▸ Filesystem
▸ Databases
▸ Global Functions + Variables
▸ Static Method Calls + Properties
▸ Forking

Side Effect #2:
A method call on another object

if (! $customer->getData('customer_activated') {
$this->getSession()->logout();
$this->getDisplay()->showLoginAbortedMessage();
}

TESTING
RETURN VALUES
IS EASIER THAN
SIDE EFFECTS

Avoid creating methods that do both:
side effect && return value

ALSO TEST FOR
EXCEPTIONS

Key Points

▸ Separation between
Hooks or Entry Points
and
Business Logic

▸ Split Business Logic into specific classes

▸ Use IDCDD to find where to separate

▸ Also separate code that
returns a value
from code that
causes a side effect

▸ Test if a class fulfills it's purpose

▸ Don't use magic methods
(No more calls to __call())

▸ Avoid method call chaining
(Don't return $this);

▸ Mainly for Magento 1.x:
Make dependencies injectable for testing

...and have fun testing!

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(thank you)

Writing testable Code (MageTitans Mini 2016)

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