If you enter "requiremets testing" in a seach string of your browser, only one (!!!) relevant result will be returned. Another ones associated with "requirements to requirements" which different in different sources. An experience of mine and my collegues (testers ana analysts) demonstrates that this is a rare activity.
Having become interested this problem a year ago, I began to collect tips on requirements testing and debug them on my projects and on projects of my colleagues from other companies. Not many has collected for a while, but there are results that I want to share with you. Among them: what is a benefit, fun, what are difficulties of requirements testing.