[REM-3439] Viewable impressions tracking

[ZSnake]

Viewable impressions tracking

For context, we're introducing viewable impressions tracking for Sponsored listings to get a better outlook on wether a sponsored product was actually viewed by the end user. This PR will introduce

• trackResultsImpressionView to the tracker.js
• Necessary types to tracker.d.ts
• Tests

References

• RFC
• Project

[esezen]

Looking good, I left two small comments

[Copilot]

Pull request overview

Adds a new Tracker API for “results impression view” events to support viewable impressions tracking, including TypeScript typings and accompanying unit tests.

Changes:

• Added trackResultsImpressionView to src/modules/tracker.js to POST /v2/behavioral_action/impression_view.
• Added trackResultsImpressionView typings to src/types/tracker.d.ts.
• Added a comprehensive test suite for trackResultsImpressionView in spec/src/modules/tracker.js.

Reviewed changes

Copilot reviewed 2 out of 3 changed files in this pull request and generated 4 comments.

File	Description
src/types/tracker.d.ts	Adds the new trackResultsImpressionView method signature to the Tracker type definitions.
src/modules/tracker.js	Implements the trackResultsImpressionView tracking call and request construction.
spec/src/modules/tracker.js	Adds unit tests validating request/response behavior for the new tracking method.

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[constructor-claude-bedrock]

Code Review

This PR introduces trackResultsImpressionView for viewable impressions tracking of Sponsored listings, adding the tracker method, TypeScript types, and tests. The implementation is clean and consistent with existing patterns, but has a few issues worth addressing.

Inline comments: 4 discussions added

Overall Assessment: ⚠️ Needs Work

[constructor-claude-bedrock]

Suggestion: The type expression Required<Pick<ItemTracked, 'itemId' | 'itemName'>> & Omit<ItemTracked, 'itemId' | 'itemName' | 'price'> is functionally correct but difficult to read at a glance. Since ItemTracked already has all these fields defined, consider defining a dedicated ResultsImpressionViewItem interface in src/types/index.d.ts for clarity:

export interface ResultsImpressionViewItem {
  itemId: string;        // required
  itemName: string;      // required
  variationId?: string;
  slCampaignId?: string;
  slCampaignOwner?: string;
}

This also makes the public API surface more self-documenting.

[constructor-claude-bedrock]

Suggestion: The test suite covers most error and happy-path scenarios well. However, there is no test verifying that slCampaignId and slCampaignOwner fields are correctly serialized to sl_campaign_id and sl_campaign_owner in the request body when passed as optional item properties. While the first required-parameters test does include these fields and checks deep.equal, it would be more explicit to have a dedicated optional-item-properties test (similar to how filterName/filterValue/searchTerm get their own optional-parameters test) to confirm the snake_case transformation of sponsored listing fields is correct independently.