Fix Vbd destructor

lib/fog/compute/xen_server/models/vdi.rb

@@ -52,7 +52,7 @@ def can_be_destroyed?
           end
 
           def destroy
-            return service.destroy_vdi(reference) if can_be_destroyed?
+            return service.destroy_record(reference, provider_class) if can_be_destroyed?
             false
           end
         end

spec/fog/compute/xen_server/models/vbd_spec.rb

@@ -174,8 +174,11 @@ def service.unplug_vbd(reference); true end
         vbd.type = 'Disk'
         def vbd.unplug; @plugged = false; end
         def vdi.destroy; @destroyed = true; end
+        def service.destroy_record(reference, provider_class); @destroyed = true end
         vbd.stub(:vdi, vdi) do
-          vbd.destroy
+          vbd.stub(:service, service) do
+            vbd.destroy
+          end
         end
       end
 
@@ -187,15 +190,5 @@ def vdi.destroy; @destroyed = true; end
         vdi.instance_variable_get(:@destroyed).must_equal(true)
       end
     end
-
-    describe 'on a cd' do
-      before :each do
-        vbd.type = 'CD'
-      end
-
-      it 'should return nil' do
-        vbd.destroy.must_equal(nil)
-      end
-    end
   end
 end

spec/fog/compute/xen_server/models/vdi_spec.rb

@@ -137,17 +137,18 @@ def self.read_identity
   end
 
   describe '#destroy' do
-    describe "when it can be unplugged" do
+    describe 'when it can be destroyed' do
       before :each do
         def vdi.can_be_destroyed?; true end
-        def service.destroy_vdi(reference); true end
-      end
-
-      it 'should return true' do
+        def service.destroy_record(reference, provider_class); @destroyed = true end
         vdi.stub(:service, service) do
           vdi.destroy.must_equal(true)
         end
       end
+
+      it 'should destroy it' do
+        service.instance_variable_get(:@destroyed).must_equal(true)
+      end
     end
 
     describe 'when can not be destroyed' do