[AbstractTarget] Document and clean up #add_build_configuration behav…

…iour

lib/xcodeproj/project/object/native_target.rb

@@ -124,7 +124,8 @@ def build_configurations
         end
 
         # Adds a new build configuration to the target and populates its with
-        # default settings according to the provided type.
+        # default settings according to the provided type if one doesn't
+        # exists.
         #
         # @note   If a build configuration with the given name is already
         #         present no new build configuration is added.
@@ -136,8 +137,13 @@ def build_configurations
         #         The type of the build configuration used to populate the build
         #         settings, must be :debug or :release.
         #
-        def add_build_configuration(name, type, skip_existing_names = true)
-          unless build_configuration_list[name]
+        # @return [XCBuildConfiguration] the created build configuration or the
+        #         existing one with the same name.
+        #
+        def add_build_configuration(name, type)
+          if existing = build_configuration_list[name]
+            existing
+          else
             build_configuration = project.new(XCBuildConfiguration)
             build_configuration.name = name
             build_configuration.build_settings = ProjectHelper.common_build_settings(type, platform_name, deployment_target, product_type)

spec/project/object/native_target_spec.rb

@@ -155,6 +155,17 @@ module ProjectSpecs
           @sut.build_configurations.map(&:name).grep('App Store').size.should == 1
         end
 
+        it "returns the new build configuration" do
+          conf = @sut.add_build_configuration('App Store', :release)
+          conf.name.should == 'App Store'
+        end
+
+        it "returns the existing build configuration" do
+          conf_1 = @sut.add_build_configuration('App Store', :release)
+          conf_2 = @sut.add_build_configuration('App Store', :release)
+          conf_1.object_id.should == conf_2.object_id
+        end
+
       end
 
       #----------------------------------------#