Allow updating of settings through the gui

lib/launchpad/settings.rb

@@ -21,10 +21,29 @@ def initialize
       @settings = YAML.load_file PATH
     end
 
+    # Reads the given attribute from memory.
     # @param option [Symbol] the attribute to be accessed from settings.
     # @return [String] the value associated with the provided attribute.
     def read(option)
       settings[option.to_s].to_s
     end
+
+    # Updates the given value in memory.
+    # @param option [Symbol] the attribute to be updated.
+    # @param value [String] the new value to be used.
+    # @return self
+    def update(option, value)
+      settings[option.to_s] = value
+    end
+
+    # Writes the current settings and their and values to disk as yaml.
+    # @return self
+    def save
+      File.open PATH, 'w' do |file|
+        file.write settings.to_yaml
+      end
+
+      self
+    end
   end
 end

spec/fixtures/config/settings.yml

@@ -0,0 +1,5 @@
+install: test/install
+local_index_path: test/index
+remote_index_uri: http://patcher.example.com/index
+login_server: http://login.example.com/
+port: 12345

spec/lib/launchpad/settings_spec.rb

@@ -1,12 +1,46 @@
 require 'spec_helper'
 
 describe Launchpad::Settings do
+  let(:settings_fixture) { 'spec/fixtures/config/settings.yml' }
+  let(:settings_path) { 'spec/fixtures/config/current-settings.yml' }
+
+  before do
+    FileUtils.copy settings_fixture, settings_path
+    stub_const 'Launchpad::Settings::PATH', settings_path
+  end
+
+  after do
+    File.delete settings_path
+  end
+
   describe '.read' do
     it 'should access saved settings' do
       expect(described_class.read :install)
         .to eq 'test/install'
+
       expect(described_class.read :login_server)
         .to eq 'http://login.example.com/'
     end
   end
+
+  describe '.update' do
+    it 'should update a given settings value' do
+      expect { described_class.update :install, 'test/updated' }
+        .to change { described_class.read :install }
+        .from('test/install')
+        .to('test/updated')
+    end
+  end
+
+  describe '.save' do
+    before do
+      described_class.update :install, 'test/updated'
+      described_class.save
+    end
+
+    it 'should update the yaml file with new values' do
+      expect(described_class.clone.read :install)
+        .to eq 'test/updated'
+    end
+  end
 end