Fixes #202 - Implement a feature check for npm

lib/puppet/feature/npm.rb

@@ -0,0 +1,18 @@
+require 'puppet/util/feature'
+
+Puppet.features.add(:npm) do
+
+  def self.which(cmd)
+    exts = ENV['PATHEXT'] ? ENV['PATHEXT'].split(';') : ['']
+    ENV['PATH'].split(File::PATH_SEPARATOR).each do |path|
+      exts.each { |ext|
+        exe = File.join(path, "#{cmd}#{ext}")
+        return exe if File.executable?(exe) && !File.directory?(exe)
+      }
+    end
+    return nil
+  end
+
+  !self.which('npm').nil? && !self.which('npm').empty?
+
+end

lib/puppet/provider/package/npm.rb

@@ -3,6 +3,8 @@
 Puppet::Type.type(:package).provide :npm, :parent => Puppet::Provider::Package do
   desc 'npm is the package manager for Node.js. This provider only handles global packages.'
 
+  confine :feature => :npm
+
   has_feature :versionable
 
   if Puppet::Util::Package.versioncmp(Puppet.version, '3.0') >= 0