# File lib/fakefs/base.rb, line 25
    def activate!
      Object.class_eval do
        remove_const(:Dir)
        remove_const(:File)
        remove_const(:FileTest)
        remove_const(:FileUtils)
        remove_const(:Pathname) if RUBY_VERSION >= '1.9.3'

        const_set(:Dir,       FakeFS::Dir)
        const_set(:File,      FakeFS::File)
        const_set(:FileUtils, FakeFS::FileUtils)
        const_set(:FileTest,  FakeFS::FileTest)
        const_set(:Pathname,  FakeFS::Pathname) if RUBY_VERSION >= '1.9.3'
        ::FakeFS::Kernel.hijack!
      end

      @activated = true

      true
    end