|There are various ways to test for wool content. If you burn it, you can smell burning hair and it looks like burning hair, for example, but I like to know how much wool there is.
If you buy mystery flatfold fabric like I do, and you want to confirm amount of wool content, cut off a swatch and cover it in bleach in a small container. Thinner fabrics take a couple of hours, allow more time for a coating.
You'll see wool "dissovling" in a chemical reaction. The fiber remaining in the bleach is not wool.
You may want to avoid selvedge as it can be woven with non-wool stabilzer fibers and so it won't give you accurate feedback on content.
This has saved me from dissappointment a few times when I wanted a tailored garment and wanted to work with wool, and I found while my fabric looked wooly and felt wooly to the touch, it had minimal wool content and wasn't suitable for my pattern.