What is the test for interpreting ambiguous or uncertain terms in an insurance policy?

On the other hand, " '[i]f the terms of a promise are in any respect ambiguous or uncertain, it must be interpreted in the sense in which the promisor believed, at the time of making it, that the promisee understood it.' This rule, as applied to a promise of coverage in an insurance policy, protects not the subjective beliefs of the insurer but, rather, 'the objectively reasonable expectations of the insured.' Only if this rule does not resolve the ambiguity do we then resolve it against the insurer. [] In summary, a court that is faced with an argument for coverage based on assertedly ambiguous policy language must first attempt to determine whether coverage is consistent with the insured's objectively reasonable expectations. In so doing, the court must interpret the language in context, with regard to its intended function in the policy. This is because 'language in a contract must be construed in the context of that instrument as a whole, and in the circumstances of that case, and cannot be found to be ambiguous in the abstract.' " (Bank of the West v. Superior Court, supra, 2 Cal.4th at pp. 1264-1265; italics in original, citations omitted.)