Usage of Gem::Deprecate.deprecate

gem_deprecate.rb

class Test
  extend Gem::Deprecate

  # DEPRECATED
  def foo
    puts "foo"
  end
  
  def bar
    puts "bar"
  end
  deprecate :foo, :bar, 2018, 10
end

t = Test.new
t.foo
#=> NOTE: Test#foo is deprecated; use bar instead. It will be removed on or after 2018-10-01.
#   Test#foo called gem_deprecate.rb:16.
#   foo

t.bar 
#=> bar