homework and exercises - How to find out whether a transformation is a canonical transformation?

We had a couple of examples where we were supposed to calculate the Canonical Transformation (CT), but we never actually talked about a condition that decides whether a transformation is a canonical one or not.

Let me give you an example: We had the transformation:

$$P=q \cdot \cot(p), \qquad Q=\ln \left(\frac{\sin(p)}{q}\right).$$ How do I see whether this transformation is a canonical one or not?

You don't have to carry out the full calculation, but maybe you can give me a hint what I need to show here?