RSpec stubbing out a file

master.pp

class profile::master {
  file { '/etc/puppetlabs/puppetserver/ssh/id-control_repo.rsa':
    ensure  => file,
    owner   => 'pe-puppet',
    mode    => '0600',
    content => file('/etc/puppetlabs/id-control_repo.rsa'),
  }
}

master_spec.rb

require 'spec_helper'

describe 'profile::master' do
  on_supported_os(
    supported_os: [
      {
        'operatingsystem' => 'CentOS',
        'operatingsystemrelease' => [
          '7',
        ],
      },
    ],
  ).each do |os, facts|
    context "on #{os}" do
      let(:facts) do
        facts.merge(
          puppetversion: Puppet.version,
        )
      end
      before(:each) do
        allow(File).to receive(:file?).and_call_original
        allow(File).to receive(:file?).with('/etc/puppetlabs/id-control_repo.rsa').and_return(true)
        allow(File).to receive(:exist?).and_call_original
        allow(File).to receive(:exist?).with('/etc/puppetlabs/id-control_repo.rsa').and_return(true)
        allow(File).to receive(:read).and_call_original
        allow(File).to receive(:read).with('/etc/puppetlabs/id-control_repo.rsa').and_return('foo')
        allow(File).to receive(:open).and_call_original
        allow(File).to receive(:open).with('/etc/puppetlabs/id-control_repo.rsa', 'w') { 'foobar' }
        # Doing this says expected '/etc/puppetlabs-id-control_repo.rsa' but got all json files it could find recursively.
        # Puppet::Parser::Functions.newfunction(:file, type: :rvalue) { |args|
        #   #raise ArgumentError, 'expected foobar' unless args[0] == 'foobar'
        #   'hello world'
        # }
      end
      #
      # Complains undefined method scope (which is supposedly available in rspec-puppet > 2.2.0)
      #
      # before(:each) { scope.expects(:file).with('/etc/puppetlabs/id-control_repo.rsa').returns('file content') }

      %w[profile::master].each do |puppet_class|
        it {
          expect(File).to receive(:open).and_call_original
          expect(File).to receive(:open).with('/etc/puppetlabs/id-control_repo.rsa','r') { 'foobar' }
          expect(File).to receive(:read).and_call_original
          expect(File).to receive(:read).with('/etc/puppetlabs/id-control_repo.rsa').and_return('contents')
          is_expected.to contain_class(puppet_class)
        }
      end
      it { is_expected.to compile.with_all_deps }
    end
  end
end