What do you call QA testing on UI?

I need to test on what I usually call UI design consistency: namely, the relation between a design and its implementation, considering only the visual aspects, leaving out any other consideration. One example is when clients ask for "pixel perfect" implementation.

So, it's basically a visual QA. The term is a direct translation for what we use in Spanish, so I thought it was correct

Today I was talking to an English speaking UX team and when the term came aloud, I discovered everybody named it in different ways and while we all understood what were we talking about, there wasn't a single way to name it.

So my question is: does this testing modality have a naming convention in English? If so, which one?