(voxpupuli#77) Add duplicate factset file test

Previously there were many default fact files which are just duplicates.  This
commit adds a test will performs a simple file hash comparison of all default
factset files and fails and displays any duplicate factsets.

This test is initially skipped while the duplicate files are removed in later
commits.

spec/facts_spec.rb

@@ -0,0 +1,35 @@
+require 'spec_helper'
+require 'digest'
+
+RSpec::Matchers.define :have_a_unique_hash do |expected|
+  match do |actual|
+    actual.count == 1
+  end
+
+  failure_message do |actual|
+    "expected that fact files #{actual.join(', ')} would be unique"
+  end
+end
+
+describe 'Default Facts' do
+  before(:each) do
+    ENV['FACTERDB_SKIP_DEFAULTDB'] = nil
+    FacterDB.instance_variable_set(:@database, nil)
+  end
+
+  describe 'fact files' do
+    xit 'should not contain duplicate fact sets' do
+      # Gather all of the default files and hash the content
+      file_hashes = {}
+      FacterDB.default_fact_files.each do |filepath|
+        file_hash = Digest::SHA256.hexdigest( File.open(filepath, 'rb') { |file| file.read } )
+        file_hashes[file_hash] ||= []
+        file_hashes[file_hash] << filepath
+      end
+
+      file_hashes.keys.each do |file_hash|
+        expect(file_hashes[file_hash]).to have_a_unique_hash
+      end
+    end
+  end
+end