module RSpec::Matchers

predicate.
(e.g. be_empty), letting you choose the prefix that best suits the
"be_an_" (e.g. be_an_instance_of), "be_a_" (e.g. be_a_kind_of) or "be_"
The arbitrary_predicate feature will handle any predicate prefixed with

RSpec will match convert that into a query against the target object.
false. Given be_ followed by arbitrary_predicate (without the "?"),
Predicates are any Ruby method that ends in a "?" and returns true or

condition (to be or not to be).
nil (respectively). Given no args means the caller should satisfy an if
Given true, false, or nil, will pass if actual value is true, false or

expect(actual).not_to be_[arbitrary_predicate](*args)
expect(actual).not_to be_nil
expect(actual).to be_[arbitrary_predicate](*args)
expect(actual).to be_nil
expect(actual).to be_falsey
expect(actual).to be_truthy
@example

def be(*args)
  args.empty? ?
    Matchers::BuiltIn::Be.new : equal(*args)
end