What is the test for establishing that a plaintiff has been defrauded by a third party to his business?

Saskatchewan, Canada

The following excerpt is from Kulyk v Wildman (Weight Loss Forever Consulting), 2012 SKQB 312 (CanLII):

As stated by Goddard L.J. in Draper v. Trist, [1939] 3 All E.R. 513, at 526: ... The law assumes, or presumes, that, if the goodwill of a man’s business has been interfered with by the passing‑off of goods, damage results therefrom. He need not wait to show that damage has resulted. He can bring his action as soon as he can prove the passing‑off, because it is one of the class of cases in which the law presumes that the plaintiff has suffered damage. ... BALANCE OF CONVENIENCE

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