class RSpec::Mocks::ProxyForNil

def add_message_expectation(location, method_name, opts={}, &block)
  warn(method_name) if warn_about_expectations?
  super
end

def add_negative_message_expectation(location, method_name, &implementation)
  warn(method_name) if warn_about_expectations?
  super
end

def add_stub(location, method_name, opts={}, &implementation)
  warn(method_name) if warn_about_expectations?
  super
end

def initialize
  @warn_about_expectations = true
  super nil
end

def warn method_name
  non_rspec_caller = caller.find { |line| !line.include?('lib/rspec/mocks') }
  Kernel.warn("An expectation of :#{method_name} was set on nil. Called from #{non_rspec_caller}. Use allow_message_expectations_on_nil to disable warnings.")
end