add path for grep command

Signed-off-by: Emilien Macchi <emilien.macchi@enovance.com>

spec/classes/cloud_volume_storage_spec.rb

@@ -58,6 +58,13 @@ describe 'cloud::volume::storage' do
 
     end
 
+    it 'checks if Cinder DB is populated' do
+      should contain_exec('cinder_db_sync').with(
+        :command => '/usr/bin/cinder-manage db sync',
+        :unless  => '/usr/bin/mysql cinder -h 10.0.0.1 -u cinder -psecrete -e "show tables" | /bin/grep Tables'
+      )
+    end
+
     it 'configure cinder volume with rbd backend' do
 
       should include_class('cinder::volume')