bugfix for Firefox for some ads that use document.write

[jarnix]

Type of change

• [x ] Bugfix

Description of change

This is a fix targeted for Firefox that creates an entry in history after a document.write. It means that when an ad uses document.write (as we see in a lot of ads on our 30 M users network), the user has to click the "back" button twice to go back. The bug is 17 years old (https://bugzilla.mozilla.org/show_bug.cgi?id=148794) and the workaround is described here for example : https://stackoverflow.com/questions/19624452/workaround-to-firefox-creating-new-history-after-each-document-write/32677679#32677679 .

[jarnix]

I don't understand why the test in Circle CI would be failing and I surely don't want to modify the test. Please, can someone more experienced with the tests of this project can check the code ?

[bretg]

@jarnix - please take a look at the unit tests that are failing due to this change. I would call this a pretty important change that could break even more -- unit tests don't try renders in all browsers.

Please describe the problem you're trying to solve and help us understand why adding doc.open is necessary and safe for other browsers.

[jarnix]

@bretg I agree with you, it's a "pretty important change", that's why I did not want to modify the tests but I got it why the test was failing. The doc.open method was called but not monitored by sinon.spy() so I added it. So now the tests are okay in the CI, but I really would like a human check though..

[harpere]

I think this is fine.

[jsnellbaker]

LGTM; I tested this change in Chrome and Firefox with banner/outstream type ads as well as using the Universal Creative templates in both safeframe/non-safeframe setups. The ads rendered fine in all cases.