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A/B Testing: Configuration

This page describes the service-specific configuration required to make the A/B test work. Both services must be configured correctly and in sync for the test to function as intended.

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For the high-level overview of how the A/B test works, see A/B Testing Overview.

brekz-prestashop

brekz-prestashop is responsible for two things:

  1. Setting the AB_templating cookie server-side to assign visitors to a test group.
  2. Rewriting links client-side so that variant B visitors are sent to the www2.* subdomain.

The AB_templating cookie is set server-side in PHP. Visitors assigned to variant B receive the value B.

The cookie is set within the root web/index.php PrestaShop dispatch file.

A JavaScript module in brekz-prestashop reads the AB_templating cookie and rewrites links when the visitor is in variant B.

Behavior:

  • Runs on every page load within brekz-prestashop.
  • Reads the AB_templating cookie value.
  • If the value is B, it finds all links matching the Category page 2012 variant URL pattern.
  • Rewrites those links to use the www2.* subdomain instead of www.*.

Example rewrite:

Before: https://www.brekz.nl/categorie/honden-speelgoed
After:  https://www2.brekz.nl/categorie/honden-speelgoed

This logic is implemented in the web/themes/brekz-2017/resources/js/global.js JavaScript file.

Targeted link patterns:

The script specifically targets URLs that correspond to Category page 2012 variant pages. Other page types (PDP, checkout, account, etc.) are not rewritten and remain on brekz-prestashop.

It fetches a JSON file which contains all Category page 2012 variant page URL's for the specific shop and language. 

fetch('/cache/page_index_' + id_shop + '_' + id_lang +'.json')

brekz-website

brekz-website is responsible for serving pages to variant B visitors arriving on the www2.* subdomain.

Environment Variables

Two .env variables control the A/B test behaviour in brekz-website:

Variable Example value Description
ABTEST_CATEGORY2012_ENABLED true Enables brekz-website to serve Category page 2012 variant pages. Set to false to disable without removing the configuration.
ABTEST_CATEGORY2012_HOSTNAME www2.brekz.nl The hostname brekz-website uses to identify incoming variant B traffic. Requests on this hostname are handled as Category page 2012 variant pages.

Example .env entry:

# A/B Testing — Category page 2012 variant
ABTEST_CATEGORY2012_ENABLED=true
ABTEST_CATEGORY2012_HOSTNAME=www2.brekz.nl

Per-country configuration

ABTEST_CATEGORY2012_HOSTNAME accepts a single hostname. When expanding the test to additional countries (e.g. www2.brekz.be), verify how brekz-website handles multi-country hostname configuration and update accordingly.

Configuration Checklist

Use this checklist when enabling the A/B test for a new country or page type:

  • AB_templating cookie assignment logic covers the new country/domain
  • JavaScript link manipulation is updated to include the new country's domain
  • www2.* subdomain is provisioned and routed to brekz-website (DNS + Cloudflare)
  • ABTEST_CATEGORY2012_ENABLED=true is set in brekz-website .env
  • ABTEST_CATEGORY2012_HOSTNAME is set to the correct www2.* hostname for the country
  • End-to-end test: visit www.*, verify cookie is set to B, click a category link, verify redirect to www2.*, verify page renders correctly