Make the position parameter work properly

lib/puppet/provider/pam/augeas.rb

@@ -45,6 +45,37 @@ def self.target(resource = nil)
     end
   end
 
+  def self.position_path (position, type)
+    placement, identifier, value = position.split(/ /)
+    key = !!value
+    if PAM_POSITION_ALIASES[key].has_key? identifier
+      expr = PAM_POSITION_ALIASES[key][identifier]
+      expr = key ? expr % [type, value] : expr % [type]
+    else
+      # if the identifier is not in the mapping
+      # we assume that its an xpath and so
+      # join everything after the placement
+      expr = position.split(/ /)[1..-1].join(" ")
+    end
+    return expr, placement
+  end
+
+  def in_position?
+    unless resource[:position].nil?
+      path, before = self.class.position_path(resource[:position], resource[:type])
+
+      if before == 'before'
+        mpath = "#{resource_path}[following-sibling::#{path}]"
+      else
+        mpath = "#{resource_path}[preceding-sibling::#{path}]"
+      end
+
+      augopen do |aug|
+        !aug.match(mpath).empty?
+      end
+    end
+  end
+
   def self.instances
     augopen do |aug|
       resources = []
@@ -78,19 +109,10 @@ def self.instances
     type = resource[:type].to_s
     control = resource[:control]
     position = resource[:position]
-    placement, identifier, value = position.split(/ /)
-    key = !!value
-    if PAM_POSITION_ALIASES[key].has_key?(identifier)
-      expr = PAM_POSITION_ALIASES[key][identifier]
-      expr = key ? expr % [type, value] : expr % [type]
-    else
-      # if the identifier is not in the mapping
-      # we assume that its an xpath and so
-      # join everything after the placement
-      identifier = position.split(/ /)[1..-1].join(" ")
-      expr = identifier
+    unless position.nil?
+      expr, placement = self.position_path(position, type)
+      aug.insert("$target/#{expr}", path, placement == 'before')
     end
-    aug.insert("$target/#{expr}", path, placement == 'before')
     if resource[:optional] == :true
       aug.touch("#{entry_path}/optional")
     end

spec/unit/puppet/provider/pam/augeas_spec.rb

@@ -131,6 +131,27 @@
                           :arguments => ["try_first_pass","retry=3","type="],})
     end
 
+    describe "when reodering settings" do
+      it "should change the order of an entry" do
+        apply!(Puppet::Type.type(:pam).new(
+          :title       => "Change the order of pam_unix.so",
+          :service     => "system-auth",
+          :type        => "auth",
+          :control     => "sufficient",
+          :module      => "pam_unix.so",
+          :arguments   => ["nullok","try_first_pass"],
+          :target      => target,
+          :provider    => "augeas",
+          :position    => "before module pam_env.so",
+          :ensure      => "positioned"
+        ))
+
+        aug_open(target, "Pam.lns") do |aug|
+          expect(aug.get("./1/module")).to eq("pam_unix.so")
+        end
+      end
+    end
+
     describe "when creating settings" do
       it "should create simple new entry" do
         apply!(Puppet::Type.type(:pam).new(