class-experimental-abtest.php
<?php
/**
* NOTE: this is a temporary class and can be replaced by jetpack-abtest after
* https://github.com/Automattic/jetpack/issues/19596 has been fixed.
*
* A class that interacts with Explat A/B tests.
*
* This class is experimental. It is a fork of the jetpack-abtest package and
* updated for use with ExPlat. These changes are planned to be contributed
* back to the upstream Jetpack package. If accepted, this class should then
* be superseded by the Jetpack class using Composer.
*
* This class should not be used externally.
*
* @package WooCommerce\Admin
* @link https://packagist.org/packages/automattic/jetpack-abtest
*/
namespace WooCommerce\Admin;
use Automattic\Jetpack\Connection\Manager as Jetpack_Connection_Manager;
use Automattic\Jetpack\Connection\Client as Jetpack_Connection_client;
use Automattic\WooCommerce\Admin\WCAdminHelper;
/**
* This class provides an interface to the Explat A/B tests.
*
* Usage:
*
* $anon_id = isset( $_COOKIE['tk_ai'] ) ? sanitize_text_field( wp_unslash( $_COOKIE['tk_ai'] ) ) : '';
* $allow_tracking = 'yes' === get_option( 'woocommerce_allow_tracking' );
* $abtest = new \WooCommerce\Admin\Experimental_Abtest(
* $anon_id,
* 'woocommerce',
* $allow_tracking
* );
*
* OR use the helper function:
*
* WooCommerce\Admin\Experimental_Abtest::in_treatment('experiment_name');
*
*
* $isTreatment = $abtest->get_variation('your-experiment-name') === 'treatment';
*
* @internal This class is experimental and should not be used externally due to planned breaking changes.
*/
final class Experimental_Abtest {
/**
* A variable to hold the tests we fetched, and their variations for the current user.
*
* @var array
*/
private $tests = array();
/**
* ExPlat Anonymous ID.
*
* @var string
*/
private $anon_id = null;
/**
* ExPlat Platform name.
*
* @var string
*/
private $platform = 'woocommerce';
/**
* Whether trcking consent is given.
*
* @var bool
*/
private $consent = false;
/**
* Request variation as a auth wpcom user or not.
*
* @var boolean
*/
private $as_auth_wpcom_user = false;
/**
* Constructor.
*
* @param string $anon_id ExPlat anonymous ID.
* @param string $platform ExPlat platform name.
* @param bool $consent Whether tracking consent is given.
* @param bool $as_auth_wpcom_user Request variation as a auth wp user or not.
*/
public function __construct( string $anon_id, string $platform, bool $consent, bool $as_auth_wpcom_user = false ) {
$this->anon_id = $anon_id;
$this->platform = $platform;
$this->consent = $consent;
$this->as_auth_wpcom_user = $as_auth_wpcom_user;
}
/**
* Returns true if the current user is in the treatment group of the given experiment.
*
* @param string $experiment_name Name of the experiment.
* @param bool $as_auth_wpcom_user Request variation as a auth wp user or not.
* @return bool
*/
public static function in_treatment( string $experiment_name, bool $as_auth_wpcom_user = false ) {
$anon_id = isset( $_COOKIE['tk_ai'] ) ? sanitize_text_field( wp_unslash( $_COOKIE['tk_ai'] ) ) : '';
$allow_tracking = 'yes' === get_option( 'woocommerce_allow_tracking' );
$abtest = new self(
$anon_id,
'woocommerce',
$allow_tracking,
$as_auth_wpcom_user
);
return $abtest->get_variation( $experiment_name ) === 'treatment';
}
/**
* Retrieve the test variation for a provided A/B test.
*
* @param string $test_name Name of the A/B test.
* @return mixed|null A/B test variation, or null on failure.
* @throws \Exception If there is an error retrieving the variation and the environment is not production.
*/
public function get_variation( $test_name ) {
// Default to the control variation when users haven't consented to tracking.
if ( ! $this->consent ) {
return 'control';
}
$variation = $this->fetch_variation( $test_name );
// If there was an error retrieving a variation, conceal the error for the consumer.
// If there was an error retrieving a variation, throw an exception in non-production environments.
if ( is_wp_error( $variation ) ) {
if ( 'production' !== wp_get_environment_type() ) {
throw new \Exception( $variation->get_error_message() );
}
return 'control';
}
return $variation;
}
/**
* Perform the request for a experiment assignment of a provided A/B test from WP.com.
*
* @param array $args Arguments to pass to the request for A/B test.
* @return array|\WP_Error A/B test variation error on failure.
*/
public function request_assignment( $args ) {
// Request as authenticated wp user.
if ( $this->as_auth_wpcom_user && class_exists( Jetpack_Connection_Manager::class ) ) {
$jetpack_connection_manager = new Jetpack_Connection_Manager();
if ( $jetpack_connection_manager->is_user_connected() ) {
$response = Jetpack_Connection_client::wpcom_json_api_request_as_user(
'/experiments/0.1.0/assignments/' . $this->platform,
'2',
$args
);
}
}
// Request as anonymous user.
if ( ! isset( $response ) ) {
if ( ! isset( $args['anon_id'] ) || empty( $args['anon_id'] ) ) {
return new \WP_Error( 'invalid_anon_id', 'anon_id must be an none empty string.' );
}
$url = add_query_arg(
$args,
sprintf(
'https://public-api.wordpress.com/wpcom/v2/experiments/0.1.0/assignments/%s',
$this->platform
)
);
$response = wp_remote_get( $url );
}
return $response;
}
/**
* Fetch and cache the test variation for a provided A/B test from WP.com.
*
* ExPlat returns a null value when the assigned variation is control or
* an assignment has not been set. In these instances, this method returns
* a value of "control".
*
* @param string $test_name Name of the A/B test.
* @return array|\WP_Error A/B test variation, or error on failure.
*/
protected function fetch_variation( $test_name ) {
// Make sure test name exists.
if ( ! $test_name ) {
return new \WP_Error( 'test_name_not_provided', 'A/B test name has not been provided.' );
}
// Make sure test name is a valid one.
if ( ! preg_match( '/^[a-z0-9_]+$/', $test_name ) ) {
return new \WP_Error( 'invalid_test_name', 'Invalid A/B test name.' );
}
// Return internal-cached test variations.
if ( isset( $this->tests[ $test_name ] ) ) {
return $this->tests[ $test_name ];
}
// Return external-cached test variations.
if ( ! empty( get_transient( 'abtest_variation_' . $test_name ) ) ) {
return get_transient( 'abtest_variation_' . $test_name );
}
// Make the request to the WP.com API.
$args = array(
'experiment_name' => $test_name,
'anon_id' => rawurlencode( $this->anon_id ),
'woo_country_code' => rawurlencode( get_option( 'woocommerce_default_country', 'US:CA' ) ),
'woo_wcadmin_install_timestamp' => rawurlencode( get_option( WCAdminHelper::WC_ADMIN_TIMESTAMP_OPTION ) ),
);
/**
* Get additional request args.
*
* @since 6.5.0
*/
$args = apply_filters( 'woocommerce_explat_request_args', $args );
$response = $this->request_assignment( $args );
// Bail if there was an error or malformed response.
if ( is_wp_error( $response ) || ! is_array( $response ) || ! isset( $response['body'] ) ) {
return new \WP_Error( 'failed_to_fetch_data', 'Unable to fetch the requested data.' );
}
// Decode the results.
$results = json_decode( $response['body'], true );
// Bail if there were no resultsreturned.
if ( ! is_array( $results ) ) {
return new \WP_Error( 'unexpected_data_format', 'Data was not returned in the expected format.' );
}
// Store the variation in our internal cache.
$this->tests[ $test_name ] = $results['variations'][ $test_name ] ?? null;
$variation = $results['variations'][ $test_name ] ?? 'control';
// Store the variation in our external cache.
if ( ! empty( $results['ttl'] ) ) {
set_transient( 'abtest_variation_' . $test_name, $variation, $results['ttl'] );
}
return $variation;
}
}
