What is the test for estoppel?

The plaintiff relies on the criteria for estoppel by convention set out in Ryan v. Moore, 2005 SCC 38, as follows at para. 59: 1. The parties' dealings must have been based on a shared assumption of fact or law: estoppel requires manifest representation by statement or conduct creating a mutual assumption. Nevertheless, estoppel can arise out of silence (impliedly). 2. A party must have conducted itself, i.e. acted, in reliance on such shared assumption, its actions resulting in a change of its legal position. 3. It must also be unjust or unfair to allow one of the parties to resile or depart from the common assumption. The party seeking to establish estoppel therefore has to prove that detriment will be suffered if the other party is allowed to resile from the assumption since there has been a change from the presumed position.