A/B Testing Module Development for 1C-Bitrix

Random rand() assignment of variants in an A/B test is why most experiments on Bitrix fail. A user sees one variant, then another — data loses meaning, statistics become useless. In 30% of cases, such audience splitting leads to false conclusions and wrong business decisions. Even modules from the Marketplace often use session_id without user binding, which causes sample ratio mismatch (SRM).

We offer a custom module vendor.abtest with deterministic assignment based on crc32 hash, conversion tracking via Bitrix events, and calculation of statistical significance (p-value, uplift, SRM). We'll evaluate your project in one day. In 5 years of work, we have implemented over 20 A/B testing modules for Bitrix projects — from small online stores to large catalogs with 50,000+ visitors per month.

How deterministic variant assignment works

The key task — one user always sees the same variant. Assignment is performed once and stored in the b_vendor_ab_assignment table. We use the hash crc32(session_id + experiment_code) for stable traffic allocation — without storing extra data. Compared to rand(), deterministic assignment is 20 times more stable and eliminates sample bias (SRM).

class AssignmentService
{
    public function getVariant(string $experimentCode): ?Variant
    {
        $experiment = ExperimentTable::getByCode($experimentCode);
        if (!$experiment || $experiment['STATUS'] !== 'running') return null;

        $sessionId = $this->getSessionId();
        $userId    = $GLOBALS['USER']->GetID() ?: null;

        $existing = AssignmentTable::getList([
            'filter' => [
                'EXPERIMENT_ID' => $experiment['ID'],
                'LOGIC'         => 'OR',
                'USER_ID'       => $userId,
                'SESSION_ID'    => $sessionId,
            ],
        ])->fetch();

        if ($existing) {
            return VariantTable::getById($existing['VARIANT_ID'])->fetch();
        }

        $hash = crc32($sessionId . $experimentCode) % 100;
        if ($hash >= $experiment['TRAFFIC_PERCENT']) return null;

        $variant = $this->selectVariant($experiment['ID']);

        AssignmentTable::add([
            'EXPERIMENT_ID' => $experiment['ID'],
            'VARIANT_ID'    => $variant['ID'],
            'USER_ID'       => $userId,
            'SESSION_ID'    => $sessionId,
        ]);

        return $variant;
    }
}

Comparison: deterministic vs rand()

Why statistical significance matters?

Without it, random fluctuation can be mistaken for an improvement. In the module's admin panel we calculate:

• Conversion = events / participants
• p-value via chi-squared test (threshold 0.05)
• Uplift relative to control
• Sample ratio mismatch — checks correctness of splitting

function chiSquaredTest(int $a_visitors, int $a_conversions, int $b_visitors, int $b_conversions): float
{
    $a_rate = $a_conversions / $a_visitors;
    $b_rate = $b_conversions / $b_visitors;
    $pooled = ($a_conversions + $b_conversions) / ($a_visitors + $b_visitors);

    $expected_a = $pooled * $a_visitors;
    $expected_b = $pooled * $b_visitors;

    return (($a_conversions - $expected_a) ** 2 / $expected_a) +
           (($b_conversions - $expected_b) ** 2 / $expected_b);
}

Source: Wikipedia – Chi-squared test

How to properly integrate the module into templates?

In a component template or layout:

$abTest  = \Vendor\AbTest\AbTestService::getInstance();
$variant = $abTest->getVariant('checkout_button_color');

$buttonClass = match ($variant?->getName()) {
    'green'  => 'btn-success',
    'orange' => 'btn-warning',
    default  => 'btn-primary',
};

In JavaScript — via data-attribute or global variable window.ABTEST_VARIANTS. Always check that the service returns an object, otherwise display control version. The JavaScript SDK of the module automatically collects click events and sends them via REST, eliminating data loss on reload.

Real case

On one online store project with 50,000 visitors per month, we implemented the A/B testing module to optimize the order button. Deterministic assignment allowed us to get a statistically significant 12% conversion uplift in 2 weeks. Without the module, such a result would be unattainable due to user migration between variants.

What's included in development?

• ORM tables for experiments, variants, assignments, and events
• Deterministic assignment service with weight support
• Target event tracking via agents and events
• Administrative interface with statistics and export
• JavaScript SDK for frontend
• Documentation and code review
• Testing on a test environment

Process

1. Analytics — together we define experiment goals, hypotheses, and key metrics.
2. Design — design ORM schema, API, and statistics interface.
3. Implementation — write assignment service, tracking, and admin panel.
4. Testing — verify assignment correctness, absence of bias, and accuracy of calculations.
5. Deployment — install module on production server and run A/B test under your control.

Development timeline

Multivariate testing (3+ variants) and server-side feature flags require separate assessment.

Typical A/B testing mistakes on Bitrix

• Using rand() without fixing the variant — breaks statistics.
• Confusion with session_id on mobile devices — assignment must be tied to an authorized user.
• Ignoring sample ratio mismatch — if distribution deviates from specified, results cannot be trusted.
• Early stopping of the test — minimum sample size should be calculated in advance.

Contact us to discuss your experiment — we'll choose the optimal module architecture for your task. Get a consultation on implementing A/B tests today. Order custom A/B testing module development — an objective experimentation tool to boost your store's conversion.

1C-Bitrix Module Development and Setup

The main trap of Bitrix is init.php. You add an OnBeforeIBlockElementUpdate handler there, then another one — a year later the file is 2000 lines, and on every hit all that code executes. We move business logic into full-fledged modules with D7 ORM, custom tables, and administrative interface. The module can be disabled, transferred to another project, covered with tests — none of that is possible with init.php. Our team has 10+ years of Bitrix experience, certified specialists, and a 6-month code guarantee. Request a consultation — we'll explain how to migrate legacy code to a modular architecture.

Why is init.php the worst place for business logic?

Init.php does not support class autoloading, lacks an isolated namespace, cannot be unit tested, and cannot be disabled without editing the file itself. Every handler written there runs on every request, even if not needed. In a module, you register handlers through EventManager, and they only execute when the event occurs. Performance difference: up to 3x with 10+ handlers.

Standard Modules: Typical Problems and Solutions

Information blocks. IBlock architecture is the first thing we review on any project. A classic mistake: one catalog infoblock with 80 properties, 30 of which are multiple. The b_iblock_element_property table swells to millions of rows, and CIBlockElement::GetList with filtering on three properties does a full scan. We move reference data to Highload-blocks, eliminate multiple properties where possible, and design the structure for 5x growth.

e-Store (sale). Cart business rules are a separate story. We set discount priorities to prevent two campaigns from giving 60% instead of 30%, connect payment handlers, and write custom validation via OnSaleOrderBeforeSaved.

Search. The built-in search module with morphology works up to 10–15 thousand elements. Beyond that — Elasticsearch. We configure it via the Bitrix search module API, indexing through CSearchFullText or custom indexers.

Highload-blocks for dictionaries, logs, user data — instead of bloated IBlocks. Direct queries via Bitrix\Highloadblock\HighloadBlockTable, custom tables instead of the EAV structure of standard infoblocks. A million records — no degradation.

Mail events. Configuration is not just templates in b_event_message. The key is SPF, DKIM, DMARC on the DNS, otherwise transactional emails go to spam. We check deliverability and set up bounce handling.

How to Design Infoblocks for Performance?

We use Highload-blocks for reference data (colors, sizes, manufacturers) that are not involved in complex queries. For SKUs — a separate infoblock with linking via IBLOCK_ELEMENT_PROPERTY. Enable INDEX_PROPERTY for frequently filtered properties. Tagged caching: when an element changes, only the related cache is cleared. Highload-blocks process up to 10x faster than infoblocks with multiple properties on volumes of 100,000 records.

Custom Module Development

Each module follows the structure /local/modules/vendor.modulename/:

• install/index.php — setup class, create tables via $DB->RunSQLBatch()
• lib/ — D7 ORM classes, extending Bitrix\Main\ORM\Data\DataManager
• admin/ — administrative pages using CAdminList, CAdminForm
• include.php — autoloading, event handler registration via EventManager::getInstance()->registerEventHandler()
• REST API endpoints via \Bitrix\Rest\RestManager

The module registers in the system, appears in the "Installed Solutions" list, and has its own settings at /bitrix/admin/settings.php?mid=vendor.modulename. It can be enabled, disabled, and updated through UpdateSystem or custom migration mechanics.

Examples of implemented tasks:

• Campaign management — visual condition builder via CAdminCalendar, timers via agents (CAgent::AddAgent), analytics linked to the sale module
• Cost calculator — React widget on the frontend, REST API in the module, formulas stored in a Highload-block
• Booking system — real-time calendar, locking via $DB->StartTransaction() / $DB->Commit() on concurrent requests, integration with channel manager via webhook

Components and Composite Cache

Component customization via result_modifier.php and component_epilog.php, not by editing template.php of the standard template. This way core updates are painless.

Composite cache ("Composite Site" technology) — the server sends ready HTML, bypassing PHP routing. Dynamic areas (cart, authorization) are loaded via CBitrixComponent::setFrameMode(true) and AJAX. TTFB drops to 30–50 ms. But there are caveats: not all components are compatible, $APPLICATION->ShowPanel() breaks composite, and careful markup of <div id="bx-composite-..."> is required.

What to Check Before Installing a Marketplace Module?

Before installing a module from the marketplace, an audit is mandatory. We check: SQL queries without prepared statements (hello SQL injection), direct use of $_REQUEST without filtering, use of outdated kernel API instead of D7, conflicts with the composite cache module. A module with no updates for over a year and a few dozen installations is likely a problem on the next PHP update. A typical case: a module calls CIBlockElement::GetList with no cache reset — the site crashes with 5000 elements.

Migration to D7

When upgrading PHP or switching to a new edition — refactor outdated calls:

• CIBlockElement::GetList() → Bitrix\Iblock\Elements\ElementTable::getList()
• CSaleOrder::GetList() → Bitrix\Sale\Order::getList()
• CModule::IncludeModule() → Bitrix\Main\Loader::includeModule() Testing on staging, rollback via git on issues.

According to official 1C-Bitrix documentation, D7 ORM is the recommended tool for working with data, providing type safety and automatic query generation.

Comparison: Init.php vs Module

Module Development Scope and Cost

What is included in module development?

• Technical specification and architectural plan
• Code following PSR-4 and Bitrix code style
• Unit tests (PHPUnit) for business logic
• Integration tests for events and REST API
• Installation, configuration, and API documentation
• Repository and documentation access
• Administrator training for module usage
• 6-month warranty support

Estimated timelines and complexity:

Cost is calculated individually — contact us for a project estimate.

Module Testing

Unit tests via PHPUnit cover business logic: discount calculation, validation, document generation. Mocks for Bitrix\Main\Application::getConnection() allow tests to be DB-independent. Integration tests verify event handlers on a real database — OnAfterIBlockElementAdd, OnSaleOrderSaved, etc. REST API endpoints are tested via curl or PHPUnit HTTP client. Critical for modules working with b_sale_order, b_catalog_price — where errors cost money.

Compatibility is checked on PHP 7.4, 8.0, 8.1, 8.2 and editions: Standard, Small Business, Business. We check conflicts with popular marketplace modules — they often intercept the same events. Load testing: measurements on 10K, 100K, 1M records, profiling via Xdebug for memory leaks and N+1 queries.

Practical Examples

Campaign module for an electronics chain. The built-in sale module discounts did not cover scenarios like "2+1", a gift with purchase over a certain amount, or combined conditions. We built a visual builder: marketers create rules via drag-and-drop without development tickets. Campaign calendar, auto-deactivation via agents, analytics linked to b_sale_order — conversion, average check, usage count. Time to launch a new campaign dropped from two days to half an hour.

Calculator for builders. Parameters (area, materials, number of floors) → formula → preliminary estimate → lead to CRM via CRest::call('crm.lead.add'). Regional coefficients and seasonal markups from a Highload-block, material prices from 1C exchange. The number of target leads increased by a third: clients see a breakdown before calling a manager.

Booking for a hotel chain. Real-time availability via AJAX requests to a custom table vendor_booking_slots, seasonal tariff calculation, synchronization with Booking.com via channel manager API. Room locking on concurrent booking via SELECT ... FOR UPDATE in transactions. Timezones handled via \DateTimeZone — a guest from Vladivostok and a manager from Moscow see the same picture.

We will evaluate your project within one day. Write to us — we'll tell you what is included in turnkey development. Contact us for a consultation on your project. Order a custom module development — get a ready solution with documentation and support.