buildMasterVideoTagFromAdserverTag() not selecting winning bid

[ronenst]

Type of issue

bug (?)

Description

If an empty bid is received before a winning response buildMasterVideoTagFromAdserverTag() will select it as the "winning bid" and not set the correct description_url.

Steps to reproduce

It is possible to reproduce this issue by setting 2 bidders on a video unit where one returns an empty response before the second one returns a winning response. This is difficult to do reliably so I will open a PR with a test case and a fix.

Assuming the test case assumptions are correct, the issue can be reproduced by applying the unit test without the fix.

Expected results

buildMasterVideoTagFromAdserverTag() should selected the winning bid for the given ad unit from the list of bids received and set the master tag description_url to the winning bid descriptionUrl

Actual results

buildMasterVideoTagFromAdserverTag() selects the first bid for the given ad unit regardless of whether it's an empty bid or not or if there is a higher CPM bid available and may set description_url to the wrong value.

Platform details

Reproduces on v0.21.0

Other information

I've done my best to understand the buildMasterVideoTagFromAdserverTag() mechanism, but I'm a little fuzzy on the details, I do have doubts that this is an actual bug, hence the (?)

[mkendall07]

Thanks for the bug report. @jaiminpanchal27 please check this out.