(bug) - Prevent duplicated fact keys

Previously, when registering a custom fact with rspec-puppet-facts, the
fact key would be converted to a string. This lead to duplicate facts
being present in the facts hash, as default fact keys are stored as sym.

To fix this, we remove a `to_s` conversion on the key in the
register_custom_fact method, unless the rspec config stringify keys is true.

lib/rspec-puppet-facts.rb

@@ -212,7 +212,8 @@ def add_custom_fact(name, value, options = {})
   # @api private
   def self.register_custom_fact(name, value, options)
     @custom_facts ||= {}
-    @custom_facts[name.to_s] = {:options => options, :value => value}
+    name = RSpec.configuration.facterdb_string_keys ? name.to_s : name.to_sym
+    @custom_facts[name] = {:options => options, :value => value}
   end
 
   # Adds any custom facts according to the rules defined for the operating

spec/rspec_puppet_facts_spec.rb

@@ -901,24 +901,34 @@
 
     it 'adds a simple fact and value' do
       add_custom_fact 'root_home', '/root'
-      expect(subject['redhat-7-x86_64']['root_home']).to eq '/root'
+      expect(subject['redhat-7-x86_64'][:root_home]).to eq '/root'
+    end
+
+    it 'overwrites fact and values' do
+      add_custom_fact :identity, { 'user' => 'root' }
+      expect(subject['redhat-7-x86_64'][:identity]).to eq({ 'user' => 'root' })
     end
 
     it 'confines a fact to a particular operating system' do
       add_custom_fact 'root_home', '/root', :confine => 'redhat-7-x86_64'
-      expect(subject['redhat-7-x86_64']['root_home']).to eq '/root'
-      expect(subject['redhat-6-x86_64']['root_home']).to be_nil
+      expect(subject['redhat-7-x86_64'][:root_home]).to eq '/root'
+      expect(subject['redhat-6-x86_64'][:root_home]).to be_nil
     end
 
     it 'excludes a fact from a particular operating system' do
       add_custom_fact 'root_home', '/root', :exclude => 'redhat-7-x86_64'
-      expect(subject['redhat-7-x86_64']['root_home']).to be_nil
-      expect(subject['redhat-6-x86_64']['root_home']).to eq '/root'
+      expect(subject['redhat-7-x86_64'][:root_home]).to be_nil
+      expect(subject['redhat-6-x86_64'][:root_home]).to eq '/root'
     end
 
     it 'takes a proc as a value' do
       add_custom_fact 'root_home', ->(_os, _facts) { '/root' }
-      expect(subject['redhat-7-x86_64']['root_home']).to eq '/root'
+      expect(subject['redhat-7-x86_64'][:root_home]).to eq '/root'
+    end
+
+    it 'accepts sym key and stores as sym' do
+      add_custom_fact :root_home, ->(_os, _facts) { '/root' }
+      expect(subject['redhat-7-x86_64'][:root_home]).to eq '/root'
     end
   end