Facter stubbing examples

fact_spec.rb

require 'rspec'
require 'facter'

describe 'facter_value' do
  context 'when stubbing Facter::Util::Collection#fact' do
    before(:each) do
      stub_fact = instance_double(Facter::Util::Fact, :value => 'foo')
      allow(Facter.collection).to receive(:fact).with(:test_fact).and_return(stub_fact)
    end

    it 'can be accessed via Facter.value' do
      expect(Facter.value(:test_fact)).to eq('foo')
    end

    it 'can be accessed via Facter::Util::Fact#value' do
      expect(Facter.fact(:test_fact).value).to eq('foo')
    end

    it 'is present in the fact collection' do
      expect(Facter.collection.fact(:test_fact)).not_to be_nil
    end
  end

  context 'when stubbing Facter::Util::Fact#value' do
    before(:each) do
      allow(Facter.fact(:test_fact)).to receive(:value).and_return('foo')
    end

    it 'can be accessed via Facter::Util::Fact#value' do
      expect(Facter.fact(:test_fact).value).to eq('foo')
    end

    it 'can not be accessed via Facter.value' do
      expect(Facter.value(:test_fact)).to be_nil
    end

    it 'is not actually present in the fact collection' do
      expect(Facter.collection.fact(:test_fact)).to be_nil
    end
  end
end