I do not like to “brand” products or advocate for one over another. This is an exception Rapitest soil test kit contains tests for N-P -K and PH.
You take a small soil sample less than a tablespoon. Screen the sample for large particles, mix the sample with water and add chemicals that react to Nitrogen, Phosphorus, and Potash.
I am a dumbass and have no problems with the tests. Just a note, use distilled for the tests.