> ## Documentation Index > Fetch the complete documentation index at: https://docs.depict.ai/llms.txt > Use this file to discover all available pages before exploring further. # Start a collection version A/B test > Splits the collection's storefront traffic between two saved versions for 7–30 days, in every market or in the given market groups. Creates the test and per-variant orderings as Shopify metaobjects; a failure rolls them back. Needs the launch flag (403) and a Custom Merchandising plan (402); a scope that overlaps a running test on the collection is a 409. Returns the created test (201). ## OpenAPI ````yaml /api-reference/openapi/lite.json post /collections/{collection_id}/ab-tests openapi: 3.1.0 info: title: Search & Merchandising API version: 1.0.0 description: >- REST API behind Depict: Search & Merchandising, the native Shopify app: onboarding, collections, boost & bury, dashboards, A/B testing and multi-store management. Endpoints are served under the /api/lite prefix and are authenticated with the Shopify session token that App Bridge issues to the embedded app. servers: - url: /api/lite security: - ShopifySessionToken: [] paths: /collections/{collection_id}/ab-tests: post: summary: Start a collection version A/B test description: >- Splits the collection's storefront traffic between two saved versions for 7–30 days, in every market or in the given market groups. Creates the test and per-variant orderings as Shopify metaobjects; a failure rolls them back. Needs the launch flag (403) and a Custom Merchandising plan (402); a scope that overlaps a running test on the collection is a 409. Returns the created test (201). operationId: collectionAbTestCreate parameters: - schema: type: string description: Numeric Shopify collection id. required: true description: Numeric Shopify collection id. name: collection_id in: path - schema: type: string description: Lite merchant id, e.g. `shopify-`. required: true description: Lite merchant id, e.g. `shopify-`. name: merchant_id in: query requestBody: required: true content: application/json: schema: $ref: '#/components/schemas/CreateCollectionVersionAbTestRequest' responses: '201': description: The created test. content: application/json: schema: $ref: '#/components/schemas/CollectionVersionAbTest' '400': description: >- The query or body failed the schema, or the merchant has no Shopify configuration. content: application/json: schema: $ref: '#/components/schemas/Detail' '401': description: Not authenticated. content: application/json: schema: $ref: '#/components/schemas/Detail' '402': description: The plan does not include version A/B tests. content: application/json: schema: $ref: '#/components/schemas/Paywall' '403': description: >- Authenticated, but this identity may not call the API, or version A/B testing is not enabled. content: application/json: schema: $ref: '#/components/schemas/Detail' '404': description: Merchant not found for this caller. content: application/json: schema: $ref: '#/components/schemas/Detail' '409': description: The scope overlaps a running test on this collection. content: application/json: schema: $ref: '#/components/schemas/Detail' '415': description: Content-Type is not application/json. content: application/json: schema: $ref: '#/components/schemas/Detail' '422': description: >- A variant version or market group cannot be tested (e.g. it does not exist). content: application/json: schema: $ref: '#/components/schemas/Detail' '500': description: Internal error. content: application/json: schema: $ref: '#/components/schemas/Detail' components: schemas: CreateCollectionVersionAbTestRequest: type: object properties: variant_a_version_uuid: type: string minLength: 1 variant_b_version_uuid: type: string minLength: 1 scope_type: type: string enum: - all - market_groups market_group_ids: type: array items: type: string default: [] description: Required (non-empty) when scope_type is market_groups. traffic_split: type: integer minimum: 10 maximum: 90 description: Percent of traffic routed to variant B. start_date: type: string format: date-time description: ISO 8601; without an offset it is read as UTC. end_date: type: string format: date-time description: ISO 8601; without an offset it is read as UTC. name: type: - string - 'null' maxLength: 80 required: - variant_a_version_uuid - variant_b_version_uuid - scope_type - traffic_split - start_date - end_date CollectionVersionAbTest: type: object properties: test_id: type: string collection_id: type: string name: type: string variant_a_version_uuid: type: string variant_b_version_uuid: type: string scope_type: type: string enum: - all - market_groups market_group_ids: type: array items: type: string applies_to_market_ids: type: array items: type: string description: >- The scope resolved to numeric Shopify market ids, sorted; two running tests on a collection never share one. traffic_split: type: integer description: Percent of traffic routed to variant B (10–90). start_date: type: string format: date-time end_date: type: string format: date-time status: type: string enum: - running - ended - winner_promoted promoted_variant: type: - string - 'null' enum: - A - B - null created_at: type: string format: date-time created_by_email: type: string description: 'Always empty: the test is storefront-readable.' required: - test_id - collection_id - name - variant_a_version_uuid - variant_b_version_uuid - scope_type - market_group_ids - applies_to_market_ids - traffic_split - start_date - end_date - status - promoted_variant - created_at - created_by_email Detail: type: object properties: detail: type: string required: - detail description: 'Every 4xx/5xx body: `{detail}`.' Paywall: type: object properties: detail: type: string code: type: string enum: - product_required - collection_limit_exceeded - installation_frozen product: type: string enum: - search - recs - vm limit: type: integer required: - detail - code description: >- 402: the merchant's plan does not include this. Branch on `code`; show `detail`. securitySchemes: ShopifySessionToken: type: http scheme: bearer bearerFormat: JWT description: >- Shopify App Bridge session token of the embedded Depict: Search & Merchandising app. The shop in the token determines the merchant; merchant_id parameters must belong to that shop. ````