ISO 9126 has a subchapter under maintainability that is called testability. In short: "The capability of the software product to enable modified software to be validated". As our department uses ISTQB to describe the way how we should test, I am searching for what ISTQB tells us about this subject.
The context: My project fails to prioritize defect fixes that are not a big issue in the live environment but support our automated test. Due to such a defect a large part of our automated regression test is now failing and the responsible owner need to be convinced that this actually decrease the value of our product. Next to my own common sense, I want to be backed up by the method we are using and have all agreed upon to follow.
(Maybe someone with enough rep can add a tag
ISTQB to my question?)