improve code to return an empty list of packages if no packages are found

lib/puppet/provider/package/pkgng.rb

@@ -9,12 +9,15 @@ Puppet::Type.type(:package).provide :pkgng, :parent => Puppet::Provider::Package
 
   def self.instances
     packages = []
-    inst = []
     begin
-      pkg_list = pkg(['info','-a']).lines
+      output = pkg(['info','-a'])
 
-      pkg_list.each do |pkgs|
-        pkgs = pkgs.split
+      if output == nil
+        return packages
+      end
+
+      output.lines.each do |line|
+        pkgs = line.split
         pkg_info = pkgs[0].split('-')
         pkg = {
           :ensure   => pkg_info.pop,

spec/unit/puppet/provider/pkgng_spec.rb

@@ -23,6 +23,11 @@ describe provider_class do
       provider_class.expects(:pkg).raises(Puppet::ExecutionFailure, 'wawawa')
       provider_class.instances.should be_nil
     end
+
+    it "should return the empty set if no packages are listed" do
+      provider_class.expects(:pkg).with(['info','-a']).yields('')
+      provider_class.instances.should be_empty
+    end
   end
 
 end