Implement better nova_admin_tenant_id_setter exists? method

Actually do some checking in the exists? method here to see if the
neutron.conf nova_admin_tenant_id setting is correct already.  That
way Puppet can properly recognize when the resource is already in
the right state.

Change-Id: I9692f4689683298cba4af1cacd700975f7e50b17
Closes-bug: 1392862

lib/puppet/provider/nova_admin_tenant_id_setter/ini_setting.rb

@@ -12,6 +12,7 @@ require 'rubygems'
 require 'net/http'
 require 'net/https'
 require 'json'
+require 'puppet/util/inifile'
 
 class KeystoneError < Puppet::Error
 end
@@ -126,6 +127,8 @@ def keystone_v2_tenants(auth_url,
 end
 
 Puppet::Type.type(:nova_admin_tenant_id_setter).provide(:ruby) do
+    @tenant_id = nil
+
     def authenticate
         keystone_v2_authenticate(
           @resource[:auth_url],
@@ -144,13 +147,19 @@ Puppet::Type.type(:nova_admin_tenant_id_setter).provide(:ruby) do
     end
 
     def exists?
-        false
+      ini_file  = Puppet::Util::IniConfig::File.new
+      ini_file.read("/etc/neutron/neutron.conf")
+      ini_file['DEFAULT'] && ini_file['DEFAULT']['nova_admin_tenant_id'] && ini_file['DEFAULT']['nova_admin_tenant_id'] == tenant_id
     end
 
     def create
         config
     end
 
+    def tenant_id
+      @tenant_id ||= get_tenant_id
+    end
+
     # This looks for the tenant specified by the 'tenant_name' parameter to
     # the resource and returns the corresponding UUID if there is a single
     # match.
@@ -174,7 +183,7 @@ Puppet::Type.type(:nova_admin_tenant_id_setter).provide(:ruby) do
 
     def config
         Puppet::Type.type(:neutron_config).new(
-            {:name => 'DEFAULT/nova_admin_tenant_id', :value => "#{get_tenant_id}"}
+            {:name => 'DEFAULT/nova_admin_tenant_id', :value => "#{tenant_id}"}
         ).create
     end
 

spec/unit/provider/nova_admin_tenant_id_setter/neutron_spec.rb

@@ -77,6 +77,19 @@ describe 'Puppet::Type.type(:nova_admin_tenant_id_setter)' do
             expect(provider.exists?).to be_false
             expect(provider.create).to be_nil
         end
+
+        context 'when tenant id already set' do
+            it 'should create a resource, with exists? true' do
+                mock = { 'DEFAULT' => { 'nova_admin_tenant_id' => 'UUID_SERVICES' } }
+                Puppet::Util::IniConfig::File.expects(:new).returns(mock)
+                mock.expects(:read).with('/etc/neutron/neutron.conf')
+
+                resource = Puppet::Type::Nova_admin_tenant_id_setter.new(params)
+                provider = provider_class.new(resource)
+                expect(provider.exists?).to be_true
+                expect(provider.create).to be_nil
+            end
+        end
     end
 
     # What happens if we ask for a tenant that does not exist?