Merge pull request #876 from chef/prevent_failure

Signed-off-by: Tim Smith <tsmith@chef.io>

lib/rubocop/cop/chef/deprecation/resource_without_unified_mode_true.rb

@@ -54,6 +54,9 @@ class ResourceWithoutUnifiedTrue < Base
           def_node_search :provides, '(send nil? :provides ...)'
 
           def on_new_investigation
+            # gracefully fail if the resource is empty
+            return if processed_source.ast.nil?
+
             # Using range similar to RuboCop::Cop::Naming::Filename (file_name.rb)
             return if unified_mode?(processed_source.ast)
             range = source_range(processed_source.buffer, 1, 0)

spec/rubocop/cop/chef/deprecation/resource_without_unified_mode_true_spec.rb

@@ -71,6 +71,10 @@
     RUBY
   end
 
+  it "doesn't register an offense when the custom resource file is empty" do
+    expect_no_offenses('')
+  end
+
   context 'with TargetChefVersion set before 15.3' do
     let(:config) { target_chef_version(15.2) }