Merge pull request #150 from ggiamarchi/issu146

Override default merge method for our configuration

source/lib/vagrant-openstack-provider/config.rb

@@ -174,6 +174,36 @@ def initialize
         @ssh_disabled = UNSET_VALUE
       end
 
+      def merge(other)
+        result = self.class.new
+
+        # Set all of our instance variables on the new class
+        [self, other].each do |obj|
+          obj.instance_variables.each do |key|
+            # Ignore keys that start with a double underscore. This allows
+            # configuration classes to still hold around internal state
+            # that isn't propagated.
+            next if key.to_s.start_with?('@__')
+
+            # Don't set the value if it is the unset value, either.
+            value = obj.instance_variable_get(key)
+            print key
+            if [:@networks, :@volumes, :@rsync_includes].include? key
+              result.instance_variable_set(key, value) unless value.empty?
+            else
+              result.instance_variable_set(key, value) if value != UNSET_VALUE
+            end
+          end
+        end
+
+        # Persist through the set of invalid methods
+        this_invalid  = @__invalid_methods || Set.new
+        other_invalid = other.instance_variable_get(:"@__invalid_methods") || Set.new
+        result.instance_variable_set(:"@__invalid_methods", this_invalid + other_invalid)
+
+        result
+      end
+
       # rubocop:disable Style/CyclomaticComplexity
       def finalize!
         @password = nil if @password == UNSET_VALUE

source/spec/vagrant-openstack-provider/config_spec.rb

@@ -62,6 +62,55 @@
     end
   end
 
+  describe 'merge' do
+    let(:foo_class) do
+      Class.new(described_class) do
+        attr_accessor :networks
+      end
+    end
+
+    subject { foo_class.new }
+
+    context 'with original network not empty' do
+      it 'should overidde the config' do
+        one = foo_class.new
+        one.networks = ['foo']
+
+        two = foo_class.new
+        two.networks = ['bar']
+
+        result = one.merge(two)
+        result.networks.should =~ ['bar']
+      end
+    end
+
+    context 'with original network empty' do
+      it 'should add the network to the existing list' do
+        one = foo_class.new
+        one.networks = []
+
+        two = foo_class.new
+        two.networks = ['bar']
+
+        result = one.merge(two)
+        result.networks.should =~ ['bar']
+      end
+    end
+
+    context 'with original network not empty and new empty' do
+      it 'should keep the original network' do
+        one = foo_class.new
+        one.networks = ['foo']
+
+        two = foo_class.new
+        two.networks = []
+
+        result = one.merge(two)
+        result.networks.should =~ ['foo']
+      end
+    end
+  end
+
   describe 'validation' do
     let(:machine) { double('machine') }
     let(:validation_errors) { subject.validate(machine)['Openstack Provider'] }