Fix: Incorrect generation of analytics impression url when bid response is a VAST URL (videoTrackers.js)

[shubham-si]

Type of change

• Bugfix

Issue

The issue arises when bid response has vastUrl as video response. Impression urls for analytics are registered via vastTrackers.registerVastTrackers function. This module gets impression urls on bidResponse and concatenate to bidResponse.vastImpUrl as Set<Array<string>>.

The videoCache.js module then add these impression urls to vast. It requires impression urls as string|string[].
The current implementation for generating CDATA blocks in <Impression> tags is incorrectly handling impression trackers when the video response is a vastUrl. Instead of embedding the actual URLs, the output is showing [object Set].

Code Ref. :

impTrackerURLs ? impTrackerURLs.map(trk => `<Impression><![CDATA[${trk}]]></Impression>`).join('') : '';

The code is meant to generate impression URLs by mapping over impTrackerURLs, which it assume is Array<string>. However, instead of producing URLs as expected, the output inside the tags is [object Set] when it should be the actual URLs as strings.

This issue will impact video ad tracking, leading to incorrect reporting and analytics.

Steps to reproduce

• Register vastTrackers function as mentioned here with any analytics adapter eg., medianetAnalytics

• It can be a single url of type event: impressions

    registerVastTrackers(MODULE_TYPE_ANALYTICS, 'test', function(bidResponse) {
      return [
        {'event': 'impressions', 'url': `https://vasttracking.mydomain1.com/vast?cpm=${bidResponse.cpm}`}
      ];
    });

• Or can be multiple url's of type event: impressions

    registerVastTrackers(MODULE_TYPE_ANALYTICS, 'test', function(bidResponse) {
      return [
        {'event': 'impressions', 'url': `https://vasttracking.mydomain1.com/vast?cpm=${bidResponse.cpm}`},
        {'event': 'impressions', 'url': `https://vasttracking.mydomain2.com/vast?cpm=${bidResponse.cpm}`}
      ];
    });

Solution

Convert the Set<string> to an array before concatenating to bidResponse.vastImpUrl.

• With videoResponse as vastUrl
  

• With videoResponse as vastXml
  

[shubham-si]

Hey @patmmccann , could you please check this MR since you have defined the spec.

[dgirardi]

I tried adding a test case for this but I am unable to update this PR.

Could you either add a test yourself, or merge in ab3bb90 ? Thanks!