For a WOC, my favorite test is the 'nude' test. Most nude lip colors pull totally pink on me. I can hold up a nude tube of lipstick, no matter how dark, and it will pull pink. Most taupes pull purple on me. The yellow and orange in my skin highlights the contrast of the cool color.
A WOC with a cool skin tone will have those colors pull more 'brown' on them. There are, however, very few WOC with cool undertones. Most have yellow, orange or red undertones. This goes for African, Indian (and otherwise) Asian descent.
On fair skins... it's easy to tell if a person is warmer or cooler by simply looking at the natural flush in the skin. Most fair skinned women are obviously cool or obviously neutral. In my career (17 years), I can count the number of 100% warm toned fair skinned beauties (not including tanned ones).