content_matcher.swift

private func beContent(test: @escaping (Response) -> Void = { _ in }) -> Predicate<State> {
    return Predicate.define("be <content>") { expression, message in
        if let actual = try expression.evaluate(),
            case let .content(response) = actual {
            test(response)
            return PredicateResult(status: .matches, message: message)
        }
        return PredicateResult(status: .fail, message: message)
    }
}