Create Configurable module

lib/ddtrace/configurable.rb

@@ -0,0 +1,52 @@
+module Datadog
+  InvalidOptionError = Class.new(StandardError)
+  # Configuratble provides configuration methods for a given class/module
+  module Configurable
+    IDENTITY = ->(x) { x }
+
+    def self.included(base)
+      base.singleton_class.include(ClassMethods)
+    end
+
+    # ClassMethods
+    module ClassMethods
+      def set_option(name, value)
+        name = name.to_sym
+
+        invalid!(name) unless options.key?(name)
+
+        options[name] = setters[name].call(value)
+      end
+
+      def get_option(name)
+        invalid!(name) unless options.key?(name)
+
+        options[name]
+      end
+
+      def configure_pin(pin)
+        pin.config = Hash(pin.config).merge(options)
+      end
+
+      private
+
+      def option(name, opts = {})
+        name = name.to_sym
+        setters[name] = opts.fetch(:setter, IDENTITY)
+        options[name] = opts[:default]
+      end
+
+      def options
+        @options ||= {}
+      end
+
+      def setters
+        @setters ||= {}
+      end
+
+      def invalid!(name)
+        raise(InvalidOptionError, "#{self} doesn't have the option: #{name}")
+      end
+    end
+  end
+end

lib/ddtrace/contrib/base.rb

@@ -1,11 +1,13 @@
 require 'ddtrace/registry'
+require 'ddtrace/configurable'
 
 module Datadog
   module Contrib
     # Base provides features that are shared across all integrations
     module Base
       def self.included(base)
         base.include(Registry::Registerable)
+        base.include(Configurable)
       end
     end
   end

test/configurable_test.rb

@@ -0,0 +1,63 @@
+require 'ddtrace/configurable'
+
+module Datadog
+  class ConfigurableTest < Minitest::Test
+    def setup
+      @module = Module.new { include(Configurable) }
+    end
+
+    def test_option_methods
+      assert_respond_to(@module, :set_option)
+      assert_respond_to(@module, :get_option)
+      assert_respond_to(@module, :configure_pin)
+    end
+
+    def test_option_default
+      @module.class_eval do
+        option :foo, default: :bar
+      end
+
+      assert_equal(:bar, @module.get_option(:foo))
+    end
+
+    def test_setting_an_option
+      @module.class_eval do
+        option :foo, default: :bar
+      end
+
+      @module.set_option(:foo, 'baz!')
+      assert_equal('baz!', @module.get_option(:foo))
+    end
+
+    def test_custom_setter
+      @module.class_eval do
+        option :shout, setter: ->(v) { v.upcase }
+      end
+
+      @module.set_option(:shout, 'loud')
+      assert_equal('LOUD', @module.get_option(:shout))
+    end
+
+    def test_pin_configuration
+      @module.class_eval do
+        option :foo
+      end
+
+      pin = Pin.new(:test_service)
+      @module.set_option(:foo, :bar)
+      @module.configure_pin(pin)
+
+      assert_equal(:bar, pin.config[:foo])
+    end
+
+    def test_invalid_option
+      assert_raises(InvalidOptionError) do
+        @module.set_option(:bad_option, 'foo')
+      end
+
+      assert_raises(InvalidOptionError) do
+        @module.get_option(:bad_option)
+      end
+    end
+  end
+end