Add factory for fabricating new ci config nodes

lib/gitlab/ci/config/node/configurable.rb

@@ -30,19 +30,10 @@ module Gitlab
 
           private
 
-          def add_node(key, metadata)
-            entry = create_entry(key, metadata[:class])
-            entry.description = metadata[:description]
-
-            @nodes[key] = entry
-          end
-
-          def create_entry(key, entry_class)
-            if @value.has_key?(key)
-              entry_class.new(@value[key])
-            else
-              Node::Null.new(nil)
-            end
+          def create_node(key, factory)
+            factory.with_value(@value[key])
+            factory.null_node unless @value.has_key?(key)
+            factory.create!
           end
 
           class_methods do
@@ -51,9 +42,8 @@ module Gitlab
             private
 
             def allow_node(symbol, entry_class, metadata)
-              node = { symbol.to_sym =>
-                       { class: entry_class,
-                         description: metadata[:description] } }
+              factory = Node::Factory.new(entry_class)
+                .with_description(metadata[:description])
 
               define_method(symbol) do
                 raise Entry::InvalidError unless valid?
@@ -61,7 +51,7 @@ module Gitlab
                 @nodes[symbol].try(:value)
               end
 
-              (@allowed_nodes ||= {}).merge!(node)
+              (@allowed_nodes ||= {}).merge!(symbol => factory)
             end
           end
         end

lib/gitlab/ci/config/node/entry.rb

@@ -27,8 +27,8 @@ module Gitlab
           end
 
           def compose!
-            allowed_nodes.each do |key, entry|
-              add_node(key, entry)
+            allowed_nodes.each do |key, factory|
+              @nodes[key] = create_node(key, factory.dup)
             end
           end
 
@@ -52,7 +52,7 @@ module Gitlab
             {}
           end
 
-          def add_node(key, entry)
+          def validate!
             raise NotImplementedError
           end
 
@@ -60,7 +60,9 @@ module Gitlab
             raise NotImplementedError
           end
 
-          def validate!
+          private
+
+          def create_node(key, factory)
             raise NotImplementedError
           end
         end

lib/gitlab/ci/config/node/factory.rb

+module Gitlab
+  module Ci
+    class Config
+      module Node
+        ##
+        # Factory class responsible for fabricating node entry objects.
+        #
+        # It uses Fluent Interface pattern to set all necessary attributes.
+        #
+        class Factory
+          class InvalidFactory < StandardError; end
+
+          def initialize(entry_class)
+            @entry_class = entry_class
+            @attributes = {}
+          end
+
+          def with_value(value)
+            @attributes[:value] = value
+            self
+          end
+
+          def with_description(description)
+            @attributes[:description] = description
+            self
+          end
+
+          def null_node
+            @entry_class = Node::Null
+            self
+          end
+
+          def create!
+            raise InvalidFactory unless @attributes.has_key?(:value)
+
+            @entry_class.new(@attributes[:value]).tap do |entry|
+              entry.description = @attributes[:description]
+            end
+          end
+        end
+      end
+    end
+  end
+end

spec/lib/gitlab/ci/config/node/factory_spec.rb

+require 'spec_helper'
+
+describe Gitlab::Ci::Config::Node::Factory do
+  describe '#create!' do
+    let(:factory) { described_class.new(entry_class) }
+    let(:entry_class) { Gitlab::Ci::Config::Node::Script }
+
+    context 'when value setting value' do
+      it 'creates entry with valid value' do
+        entry = factory
+          .with_value(['ls', 'pwd'])
+          .create!
+
+        expect(entry.value).to eq "ls\npwd"
+      end
+
+      context 'when setting description' do
+        it 'creates entry with description' do
+          entry = factory
+            .with_value(['ls', 'pwd'])
+            .with_description('test description')
+            .create!
+
+          expect(entry.value).to eq "ls\npwd"
+          expect(entry.description).to eq 'test description'
+        end
+      end
+    end
+
+    context 'when not setting value' do
+      it 'raises error' do
+        expect { factory.create! }.to raise_error(
+          Gitlab::Ci::Config::Node::Factory::InvalidFactory
+        )
+      end
+    end
+
+    context 'when creating a null entry' do
+      it 'creates a null entry' do
+        entry = factory
+          .with_value(nil)
+          .null_node
+          .create!
+
+        expect(entry).to be_an_instance_of Gitlab::Ci::Config::Node::Null
+      end
+    end
+  end
+end