def matches?(actual)
super(actual)
predicates = [:exist?, :exists?].select { |p| actual.respond_to?(p) }
existance_values = predicates.map { |p| actual.send(p, *expected) }
uniq_truthy_values = existance_values.map { |v| !!v }.uniq
case uniq_truthy_values.size
when 0; raise NoMethodError.new("#{actual.inspect} does not respond to either #exist? or #exists?")
when 1; existance_values.first
else raise "#exist? and #exists? returned different values:\n\n" +
" exist?: #{existance_values.first}\n" +
"exists?: #{existance_values.last}"
end
end