A stool sample is a reasonably accurate way of testing. You should be able to find something online. Even these, however, produce false negatives in 1/4 cases. Also, if for example the Candida are heavily embedded into the stomach, the stool sample results might suggest a lower level in your body than is actually there. Still, I found it useful clarification.
If you do this, you should not take anti-fungals 7 days before.