add boolean custom option

features/configuration/custom_options.feature

@@ -1,4 +1,3 @@
-@wip
 Feature: custom options
 
   In order to seamlessly provide my users more options
@@ -45,6 +44,7 @@ Feature: custom options
     When I run "rspec boolean_option_spec.rb"
     Then I should see "2 examples, 0 failures"
 
+@wip
   Scenario: boolean option overridden in client app
     Given a file named "boolean_option_spec.rb" with:
       """
@@ -53,12 +53,12 @@ Feature: custom options
       end
 
       Rspec.configure do |c|
-        c.custom_option = :reset
+        c.custom_option = true
       end
 
       describe "custom option" do
         it "returns the value set in the client app" do
-          Rspec.configuration.custom_option.should == :reset
+          Rspec.configuration.custom_option.should be_true
         end
 
         it "is exposed as a predicate" do

lib/rspec/core/configuration.rb

@@ -239,6 +239,17 @@ def require_files_to_run
         files_to_run.map {|f| require f }
       end
 
+      def add_option(mname, options)
+        case options[:type]
+        when :boolean
+          (class << self; self; end).class_eval do
+            attr_reader mname
+            define_method("#{mname}?") { !!(send mname) }
+          end
+          instance_variable_set "@#{mname}", options[:default]
+        end
+      end
+
     end
   end
 end

spec/rspec/core/configuration_spec.rb

@@ -261,6 +261,33 @@ def that_thing
       end
     end
 
-  end
+    describe "#add_option" do
+      describe ":type => :boolean" do
+        context "with no additional options" do
+          before { config.add_option :custom_option, :type => :boolean }
+
+          it "defaults to false" do
+            config.custom_option.should be_false
+          end
+
+          it "adds a predicate" do
+            config.custom_option?.should be_false
+          end
+        end
+
+        context "with :default => true" do
+          before { config.add_option :custom_option, :type => :boolean, :default => true }
 
+          it "defaults to false" do
+            config.custom_option.should be_true
+          end
+
+          it "adds a predicate" do
+            config.custom_option?.should be_true
+          end
+        end
+      end
+    end
+
+  end
 end