Configuration#inclusion_filter and #exclusion_filter guarantee non-nil

- Fixes #376.

lib/rspec/core/configuration.rb

@@ -349,10 +349,17 @@ def exclusion_filter=(filter)
         settings[:exclusion_filter] = filter
       end
 
+      def exclusion_filter
+        settings[:exclusion_filter] || {}
+      end
+
       def inclusion_filter=(filter)
         settings[:inclusion_filter] = filter
       end
 
+      def inclusion_filter
+        settings[:inclusion_filter] || {}
+      end
       def filter_run_including(*args)
         force_overwrite = if args.last.is_a?(Hash) || args.last.is_a?(Symbol)
           false
@@ -362,7 +369,7 @@ def filter_run_including(*args)
 
         options = build_metadata_hash_from(args)
 
-        if inclusion_filter and inclusion_filter[:line_number] || inclusion_filter[:full_description]
+        if inclusion_filter[:line_number] || inclusion_filter[:full_description]
           warn "Filtering by #{options.inspect} is not possible since " \
                "you are already filtering by #{inclusion_filter.inspect}"
         else

lib/rspec/core/world.rb

@@ -34,8 +34,8 @@ def initialize(configuration=RSpec.configuration)
         @filtered_examples = Hash.new { |hash,group|
           hash[group] = begin
             examples = group.examples.dup
-            examples = apply_exclusion_filters(examples, exclusion_filter) if exclusion_filter
-            examples = apply_inclusion_filters(examples, inclusion_filter) if inclusion_filter
+            examples = apply_exclusion_filters(examples, exclusion_filter)
+            examples = apply_inclusion_filters(examples, inclusion_filter)
             examples.uniq
           end
         }
@@ -106,13 +106,13 @@ def announce_filters
           example_groups.clear
           if filter_announcements.empty?
             reporter.message("No examples found.")
-          elsif inclusion_filter
+          elsif !inclusion_filter.empty?
             message = "No examples matched #{inclusion_filter.description}."
             if @configuration.run_all_when_everything_filtered?
               message << " Running all."
             end
             reporter.message(message)
-          elsif exclusion_filter
+          elsif !exclusion_filter.empty?
             reporter.message(
               "No examples were matched. Perhaps #{exclusion_filter.description} is excluding everything?")
           end
@@ -122,7 +122,7 @@ def announce_filters
       end
 
       def announce_inclusion_filter(announcements)
-        if inclusion_filter
+        unless inclusion_filter.empty?
           announcements << "including #{inclusion_filter.description}"
         end
       end
@@ -139,8 +139,8 @@ def find_hook(hook, scope, group, example = nil)
 
     private
 
-      def apply?(predicate, conditions)
-        lambda {|example| example.metadata.apply?(predicate, conditions)}
+      def apply?(predicate, filter)
+        lambda {|example| filter.empty? || example.metadata.apply?(predicate, filter)}
       end
 
       def declaration_line_numbers

spec/rspec/core/configuration_spec.rb

@@ -527,7 +527,20 @@ def metadata_hash(*args)
       end
     end
 
+    describe "#inclusion_filter" do
+      it "returns {} even if set to nil" do
+        config.inclusion_filter = nil
+        config.inclusion_filter.should eq({})
+      end
+    end
+
+
     describe "#exclusion_filter" do
+      it "returns {} even if set to nil" do
+        config.exclusion_filter = nil
+        config.exclusion_filter.should eq({})
+      end
+
       describe "the default :if filter" do
         it "does not exclude a spec with no :if metadata" do
           config.exclusion_filter[:if].call(nil, {}).should be_false