What is the test for dispelling suspicion of a deceased's will?

In Vout v. Hay, Sopinka, J. said the following at p. 888: ...The suspicious circumstances may be raised by (1) circumstances surrounding the preparation of the will, (2) circumstances tending to call into question the capacity of the testator, or (3) circumstances tending to show that the free will of the testator was overborne by acts of coercion or fraud. Since these suspicious circumstances may relate to various issues, in order to properly assess what effect the obligation to dispel the suspicion has on the burden of proof, it is appropriate to ask the question, “suspicion of what?”