I was wondering if we want to test multisampled textures on drivers what would be the ideal test case and how can we verify it.
Ideal for what?
First, what problem are you having that makes you want to use multisampling? What are your requirements and/or concerns about using multisampling?
That will determine your ideal test case.
Let’s assume you want to test the feature. What would be the use case and how to verify it?
If you just want to test that multisample textures work, then just use them. You render data to them (since you can’t pixel transfer into or outof them). Then you blit it to a non-multisample framebuffer for display.
The exact details of how multisample resolving works, or where the multiple samplers within the image come from, is implementation-dependent. As such, there’s no way to “verify” that it has worked. The best you can do is try a scene with a lot of polygonal aliasing and see if it helps reduce that.