How to patch File and CoreExtensions for Timecop

Question

I need to monkey-patch File. Timecop doesn't affect the time that the file system reports, which is what File.atime uses and in turn that's what HttpClient uses when posting a file to a server, which in turn means VCR doesn't quite work as desired. AFAIK, this means I can't use refinements.

I don't understand what's going on here:

class File
  def atime
    "this one happens"
  end
end

module CoreExtensions
  module File
    module TimecopCompat
      def atime
        "this one does not"
      end
    end
  end
end

File.include CoreExtensions::File::TimecopCompat

File.new('somefile').atime # --> "this one happens"

Why does the module-based monkey patching not happen? What do I need to change for it to work? Is there a different kind of monkey-patching that I should be using?

Answer 1

The issue is related to the way include appends the module to the ancestor chain. "Ruby modules: Include vs Prepend vs Extend" provides a very detailed overview of the differences between include and prepend.

Take a look at these two examples:

class Foo
  def hello
    "1"
  end
end

module Bar
  def hello
    "2"
  end
end

Foo.include Bar

Foo.new.hello
# => "1"
Foo.ancestors
# => [Foo, Bar, Object, Kernel, BasicObject]

versus

class Foo
  def hello
    "1"
  end
end

module Bar
  def hello
    "2"
  end
end

Foo.prepend Bar

Foo.new.hello
# => "2"
Foo.ancestors
# => [Bar, Foo, Object, Kernel, BasicObject]

Basically, you want to use prepend in your case as include won't override the existing method.