From 3485012819e9375a1665c0b32feefa4a565d2a01 Mon Sep 17 00:00:00 2001
From: Pedro Lambert <pedrolambert@gmail.com>
Date: Mon, 16 Oct 2017 14:45:20 -0400
Subject: [PATCH] Add `Configurable#merge_configuration` helper method

---
 lib/ddtrace/configurable.rb | 32 ++++++++++++++++++--------------
 test/configurable_test.rb   | 30 ++++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/lib/ddtrace/configurable.rb b/lib/ddtrace/configurable.rb
index caa762f5725..110a9c77f18 100644
--- a/lib/ddtrace/configurable.rb
+++ b/lib/ddtrace/configurable.rb
@@ -8,28 +8,32 @@ def self.included(base)
       base.singleton_class.send(:include, ClassMethods)
     end
 
+    def merge_configuration(options, defaults = self.class)
+      defaults.to_h.merge(options)
+    end
+
     # ClassMethods
     module ClassMethods
       def set_option(name, value)
-        assert_valid!(name)
+        __assert_valid!(name)
 
-        options[name][:value] = options[name][:setter].call(value)
+        __options[name][:value] = __options[name][:setter].call(value)
       end
 
       def get_option(name)
-        assert_valid!(name)
+        __assert_valid!(name)
 
-        options[name][:value] || options[name][:default]
+        __options[name][:value] || __options[name][:default]
       end
 
       def to_h
-        options.each_with_object({}) do |(key, meta), hash|
-          hash[key] = meta[:value]
+        __options.each_with_object({}) do |(key, _), hash|
+          hash[key] = get_option(key)
         end
       end
 
       def reset_options!
-        options.each do |name, meta|
+        __options.each do |name, meta|
           set_option(name, meta[:default])
         end
       end
@@ -39,19 +43,19 @@ def reset_options!
       def option(name, meta = {})
         name = name.to_sym
         meta[:setter] ||= IDENTITY
-        options[name] = meta
+        __options[name] = meta
       end
 
-      def options
-        @options ||= {}
+      def __options
+        @__options ||= {}
       end
 
-      def assert_valid!(name)
-        return if options.key?(name)
-        raise(InvalidOptionError, "#{pretty_name} doesn't have the option: #{name}")
+      def __assert_valid!(name)
+        return if __options.key?(name)
+        raise(InvalidOptionError, "#{__pretty_name} doesn't have the option: #{name}")
       end
 
-      def pretty_name
+      def __pretty_name
         entry = Datadog.registry.find { |el| el.klass == self }
 
         return entry.name if entry
diff --git a/test/configurable_test.rb b/test/configurable_test.rb
index 19cb54d4595..cd54fd33274 100644
--- a/test/configurable_test.rb
+++ b/test/configurable_test.rb
@@ -46,5 +46,35 @@ def test_invalid_option
         @module.get_option(:bad_option)
       end
     end
+
+    def test_merge_configuration
+      klass = Class.new do
+        include Configurable
+        option :x, default: :default_x
+        option :y, default: :default_y
+
+        attr_reader :options
+
+        def initialize(options = {})
+          @options = merge_configuration(options)
+        end
+      end
+
+      instance = klass.new(x: :custom_x, z: :custom_z)
+
+      assert_equal(:custom_x, instance.options[:x])
+      assert_equal(:default_y, instance.options[:y])
+      assert_equal(:custom_z, instance.options[:z])
+    end
+
+    def test_to_h
+      @module.class_eval do
+        option :x, default: 1
+        option :y, default: 2
+      end
+
+      @module.set_option(:y, 100)
+      assert_equal({ x: 1, y: 100 }, @module.to_h)
+    end
   end
 end