What is the test for damages for breach of a rental to own agreement?

The Plaintiff relies upon the case of Maisonneuve v. Delaurier 2007 Carswell B.C. 457 (S.C.). In that case the Vendor and Purchaser entered into a Rent to Own Agreement that provided the Purchaser with an option to purchase the property at the end of a two year period. The agreement contained provisions recognizing that the Purchaser was paying premium rent designed to save towards the purchase price. The Purchaser had delivered twelve post dated rent cheques and continued extensive renovations to the property and the Vendor subsequently relayed that they no longer wanted to sell the property. The Purchaser sought an action for specific performance for damages for breach of the agreement. The action was allowed and the specific performance was ordered.