add filter_run_excluding

lib/rspec/core/configuration.rb

@@ -213,10 +213,16 @@ def alias_example_to(new_name, extra_options={})
         RSpec::Core::ExampleGroup.alias_example_to(new_name, extra_options)
       end
 
-      def filter_run(options={})
+      def filter_run_including(options={})
         self.filter = options unless filter and filter[:line_number] || filter[:full_description]
       end
 
+      alias_method :filter_run, :filter_run_including
+
+      def filter_run_excluding(options={})
+        self.exclusion_filter = options
+      end
+
       def include(mod, filters={})
         include_or_extend_modules << [:include, mod, filters]
       end

spec/rspec/core/configuration_spec.rb

@@ -252,6 +252,20 @@ def that_thing
 
     end
 
+    describe "#filter_run" do
+      it "sets the filter" do
+        config.filter_run :focus => true
+        config.filter.should eq({:focus => true})
+      end
+    end
+
+    describe "#filter_run_excluding" do
+      it "sets the filter" do
+        config.filter_run_excluding :slow => true
+        config.exclusion_filter.should eq({:slow => true})
+      end
+    end
+
     describe "line_number=" do
       it "sets the line number" do
         config.line_number = '37'

spec/spec_helper.rb

@@ -54,9 +54,9 @@ def in_editor?
     c.color_enabled = !in_editor?
     c.filter_run :focus => true
     c.run_all_when_everything_filtered = true
-    c.exclusion_filter = { :ruby => lambda {|version|
+    c.filter_run_excluding :ruby => lambda {|version|
       !(RUBY_VERSION.to_s =~ /^#{version.to_s}/)
-    }}
+    }
     c.before(:each) do
       @real_world = RSpec.world
       RSpec.instance_variable_set(:@world, RSpec::Core::World.new)