What is the test for establishing that there is an identifiable class in a class action?

Section 2 of The Class Actions Act defines a “class” as “...two or more persons with common issues respecting a cause of action or a potential cause of action.” The test to be applied in determining whether the plaintiff has established that there is an identifiable class is described by McLachlin C.J. in Hollick v. Toronto (City), 2001 SCC 68, [2001] 3 S.C.R. 158, at para. 21: 21 The requirement is not an onerous one. The representative need not show that everyone in the class shares the same interest in the resolution of the asserted common issue. There must be some showing, however, that the class is not unnecessarily broad ‑‑ that is, that the class could not be defined more narrowly without arbitrarily excluding some people who share the same interest in the resolution of the common issue. ... [Emphasis added]