code snippets for "Why You Don’t Need Dependency Injection In Ruby" post

s1.rb

class Dependency
  def do_something_with(some_object)
    p some_object
  end
end
 
class SomeClass
  def work_your_magic_on(something)
    Dependency.new.do_something_with something
  end
end

s2.rb

class SomeClass
  def initialize(dependency)
    @dependency = dependency
  end
   
  def work_your_magic_on(something)
    @dependency.do_something_with something
  end
end

s3.rb

class SomeClass
  def work_your_magic_on(something)
    get_dependency.do_something_with something
  end
   
  private
   
  def get_dependency
    @dependency = Dependency.new if @dependency.nil?
    @dependency
  end
end

s4.rb

def test_magic
  object = SomeClass.new
  object.work_your_magic_on "some important string"
  # TODO: assert that the string was passed to the dependency correctly
end

s5.rb

class DependencySpy
  @@passed_in_objects = []
   
  def self.passed_in_objects
    @@passed_in_objects
  end
   
  def do_something_with(some_object)
    @@passed_in_objects << some_object
  end
end

s6.rb

def test_magic
  object = SomeClass.new
  def object.get_dependency
    DependencySpy.new
  end
  object.work_your_magic_on "some important string"
  assert DependencySpy.passed_in_objects.include? "some important string"
end

s7.rb

class SomeClass
   
  private
   
  def get_dependency
    @dependency = SomeOtherDependency.new if @dependency.nil?
    @dependency
  end
   
end