What is the legal test for novation in an assumption agreement?

Esson J.A. said the following about novation (at p. 26): Because novation is essentially an issue of fact, it would be wrong in principle to say, as a generalization, that assumption agreements or extension agreements, or other particular classes of documents, do or do not create a novation. The question must be decided in each case having regard to all of the circumstances of which the language of the new contract is only one. The classical statement in this province of what is required to constitute a novation is that of Begbie C.J. in Polson v. Wulffsohn (1890), 2 B.C.R. 39 at 43: ...three things must be established: first, the new debtor must assume the complete liability; second, the creditor must accept the new debtor as a principal debtor, and not merely as an agent or guarantor; third, the creditor must accept the new contract in full satisfaction and substitution for the old contract; one consequence of which is that the original debtor is discharged, there being no longer any contract to which he is a party, or by which he can be bound.