Extract configuration objects!

- Remove serializers and readers logic from Rambling::Trie module
- Add Configuration module
- Add Configuration::Properties module
- Unify readers and serializers configuration in Configuration::ProviderCollection
- Ensure tests use new configuration options appropriately

[Related to #10]

lib/rambling/trie.rb

@@ -1,8 +1,9 @@
 require 'forwardable'
+
 %w{
-  forwardable comparable compressable compressor container enumerable
-  inspectable invalid_operation readers serializers stringifyable node
-  missing_node compressed_node raw_node version
+  forwardable comparable compressable compressor configuration container
+  enumerable inspectable invalid_operation readers serializers stringifyable
+  node missing_node compressed_node raw_node version
 }.each do |file|
   require File.join('rambling', 'trie', file)
 end
@@ -12,6 +13,13 @@ module Rambling
   # Entry point for rambling-trie API.
   module Trie
     class << self
+      extend Rambling::Trie::Forwardable
+
+      delegate [
+        :readers,
+        :serializers
+      ] => :properties
+
       # Creates a new Rambling::Trie. Entry point for the Rambling::Trie API.
       # @param [String, nil] filepath the file to load the words from.
       # @param [Reader, nil] reader the file parser to get each word. See
@@ -21,7 +29,7 @@ class << self
       def create filepath = nil, reader = nil
         Rambling::Trie::Container.new do |container|
           if filepath
-            reader ||= default_reader
+            reader ||= readers.resolve filepath
             reader.each_word filepath do |word|
               container << word
             end
@@ -38,7 +46,7 @@ def create filepath = nil, reader = nil
       # @return [Container] the trie just loaded.
       # @yield [Container] the trie just loaded.
       def load filepath, serializer = nil
-        serializer ||= serializer filepath
+        serializer ||= serializers.resolve filepath
         root = serializer.load filepath
         Rambling::Trie::Container.new root do |container|
           yield container if block_given?
@@ -52,32 +60,22 @@ def load filepath, serializer = nil
       #   serializing and dumping the trie into disk. See
       #   {Rambling::Trie::Serializers Serializers}.
       def dump trie, filepath, serializer = nil
-        serializer ||= serializer filepath
+        serializer ||= serializers.resolve filepath
         serializer.dump trie.root, filepath
       end
 
-      private
-
-      def default_reader
-        Rambling::Trie::Readers::PlainText.new
+      # Provides configuration properties for the Rambling::Trie gem.
+      # @return [Properties] the configured properties of the gem.
+      # @yield [Properties] the configured properties of the gem.
+      def config
+        yield properties if block_given?
+        properties
       end
 
-      def default_serializer
-        serializers[:marshal]
-      end
-
-      def serializer filepath
-        format = File.extname filepath
-        format.slice! 0
-        serializers[format.to_sym] || default_serializer
-      end
+      private
 
-      def serializers
-        {
-          marshal: Rambling::Trie::Serializers::Marshal.new,
-          yml: Rambling::Trie::Serializers::Yaml.new,
-          yaml: Rambling::Trie::Serializers::Yaml.new,
-        }
+      def properties
+        @properties ||= Rambling::Trie::Configuration::Properties.new
       end
     end
   end

lib/rambling/trie/configuration.rb

@@ -0,0 +1,11 @@
+%w{properties provider_collection}.each do |file|
+  require File.join('rambling', 'trie', 'configuration', file)
+end
+
+module Rambling
+  module Trie
+    # Namespace for configuration classes.
+    module Configuration
+    end
+  end
+end

lib/rambling/trie/configuration/properties.rb

@@ -0,0 +1,38 @@
+module Rambling
+  module Trie
+    module Configuration
+      class Properties
+        attr_reader :readers, :serializers
+
+        def initialize
+          reset
+        end
+
+        def reset
+          reset_readers
+          reset_serializers
+        end
+
+        private
+
+        attr_writer :readers, :serializers
+
+        def reset_readers
+          plain_text_reader = Rambling::Trie::Readers::PlainText.new
+
+          self.readers = Rambling::Trie::Configuration::ProviderCollection.new 'reader', txt: plain_text_reader
+        end
+
+        def reset_serializers
+          marshal_serializer = Rambling::Trie::Serializers::Marshal.new
+          yaml_serializer = Rambling::Trie::Serializers::Yaml.new
+
+          self.serializers = Rambling::Trie::Configuration::ProviderCollection.new 'serializer',
+            marshal: marshal_serializer,
+            yml: yaml_serializer,
+            yaml: yaml_serializer
+        end
+      end
+    end
+  end
+end

lib/rambling/trie/configuration/provider_collection.rb

@@ -0,0 +1,62 @@
+module Rambling
+  module Trie
+    module Configuration
+      class ProviderCollection
+        extend Rambling::Trie::Forwardable
+
+        attr_reader :default, :name
+
+        delegate [
+          :[],
+          :[]=,
+          :keys,
+          :values,
+        ] => :providers
+
+        def initialize name, providers = {}, default = nil
+          @name = name
+          @configured_providers = providers
+          @configured_default = default || providers.values.first
+
+          reset
+        end
+
+        def add extension, provider
+          providers[extension] = provider
+        end
+
+        def default= item
+          if providers.values.any? && !providers.values.include?(item)
+            raise ArgumentError, "default #{name} should be part of configured #{name}s"
+          end
+
+          @default = item
+        end
+
+        def providers
+          @providers ||= {}
+        end
+
+        def resolve filepath
+          providers[format filepath] || default
+        end
+
+        def reset
+          providers.clear
+          configured_providers.each { |k, v| providers[k] = v }
+          self.default = configured_default
+        end
+
+        private
+
+        attr_reader :configured_providers, :configured_default
+
+        def format filepath
+          format = File.extname filepath
+          format.slice! 0
+          format.to_sym
+        end
+      end
+    end
+  end
+end

spec/lib/rambling/trie/configuration/properties_spec.rb

@@ -0,0 +1,37 @@
+require 'spec_helper'
+
+describe Rambling::Trie::Configuration::Properties do
+  let(:properties) { Rambling::Trie::Configuration::Properties.new }
+
+  describe '.new' do
+    it 'configures the serializers' do
+      serializers = properties.serializers
+      expect(serializers.keys).to match_array %i(marshal yaml yml)
+
+      expect(serializers[:marshal]).to be_instance_of Rambling::Trie::Serializers::Marshal
+      expect(serializers[:yaml]).to be_instance_of Rambling::Trie::Serializers::Yaml
+      expect(serializers[:yml]).to be_instance_of Rambling::Trie::Serializers::Yaml
+    end
+
+    it 'configures the readers' do
+      readers = properties.readers
+      expect(readers.keys).to match_array %i(txt)
+
+      expect(readers[:txt]).to be_instance_of Rambling::Trie::Readers::PlainText
+    end
+  end
+
+  describe '#reset' do
+    before do
+      properties.serializers.add :test, 'test'
+      properties.readers.add :test, 'test'
+
+      properties.reset
+    end
+
+    it 'resets the serializers and readers to initial values' do
+      expect(properties.serializers.keys).to match_array %i(marshal yaml yml)
+      expect(properties.readers.keys).to match_array %i(txt)
+    end
+  end
+end

spec/lib/rambling/trie/configuration/provider_collection_spec.rb

@@ -0,0 +1,143 @@
+require 'spec_helper'
+
+describe Rambling::Trie::Configuration::ProviderCollection do
+  let(:first_provider) { double :first_provider }
+  let(:second_provider) { double :second_provider }
+  let(:default) { nil }
+
+  let(:provider_collection) do
+    Rambling::Trie::Configuration::ProviderCollection.new(
+      'provider',
+      { one: first_provider, two: second_provider },
+      default
+    )
+  end
+
+  describe '.new' do
+    it 'has a name' do
+      expect(provider_collection.name).to eq 'provider'
+    end
+
+    it 'has the given providers' do
+      expect(provider_collection.providers)
+        .to eq one: first_provider, two: second_provider
+    end
+
+    it 'has a default provider' do
+      expect(provider_collection.default).to eq first_provider
+    end
+
+    context 'when a default is provided' do
+      let(:default) { second_provider }
+
+      it 'has that as the default provider' do
+        expect(provider_collection.default).to eq second_provider
+      end
+    end
+  end
+
+  describe 'aliases and delegates' do
+    let(:providers) { provider_collection.providers }
+
+    before do
+      allow(providers) .to receive_messages(
+        :[] => nil,
+        :[]= => nil,
+        keys: nil,
+        values: nil,
+      )
+    end
+
+    it 'delegates #[] to providers' do
+      provider_collection[:key]
+      expect(providers).to have_received(:[]).with :key
+    end
+
+    it 'delegates #[]= to providers' do
+      provider_collection[:key] = 'hello'
+      expect(providers).to have_received(:[]=).with :key, 'hello'
+    end
+
+    it 'delegates #keys to providers' do
+      provider_collection.keys
+      expect(providers).to have_received :keys
+    end
+
+    it 'delegates #values to providers' do
+      provider_collection.values
+      expect(providers).to have_received :values
+    end
+  end
+
+  describe '#add' do
+    let(:provider) { double :provider }
+
+    before do
+      provider_collection.add :three, provider
+    end
+
+    it 'adds a new provider' do
+      expect(provider_collection.providers[:three]).to eq provider
+    end
+  end
+
+  describe '#default=' do
+    context 'when the given value is in the providers list' do
+      it 'changes the default provider' do
+        provider_collection.default = second_provider
+        expect(provider_collection.default).to eq second_provider
+      end
+    end
+
+    context 'when the given value is not in the providers list' do
+      let(:provider) { double :provider }
+
+      it 'does not change the default provider' do
+        expect do
+          begin
+            provider_collection.default = provider
+          rescue
+          end
+        end.not_to change { provider_collection.default }
+      end
+
+      it 'raises an ArgumentError' do
+        expect do
+          provider_collection.default = provider
+        end.to raise_error ArgumentError
+      end
+    end
+  end
+
+  describe '#resolve' do
+    context 'when the file extension is one of the providers' do
+      it 'returns the corresponding provider' do
+        expect(provider_collection.resolve 'hola.one').to eq first_provider
+        expect(provider_collection.resolve 'hola.two').to eq second_provider
+      end
+    end
+
+    context 'when the file extension is not one of the providers' do
+      it 'returns the default provider' do
+        expect(provider_collection.resolve 'hola.unknown').to eq first_provider
+        expect(provider_collection.resolve 'hola').to eq first_provider
+      end
+    end
+  end
+
+  describe '#reset' do
+    let(:default) { second_provider }
+    let(:provider) { double :provider }
+
+    before do
+      provider_collection.add :three, provider
+      provider_collection.default = provider
+    end
+
+    it 'resets to back to the initially configured values' do
+      provider_collection.reset
+      expect(provider_collection[:three]).to be_nil
+      expect(provider_collection.default).to eq second_provider
+    end
+  end
+end