Pass parameters given to #it_should_behave_like on to the shared exam…

…ple group.

features/example_groups/shared_example_group.feature

@@ -96,6 +96,38 @@ Feature: Shared example group
             adds objects to the end of the collection
       """
 
+  Scenario: Passing parameters to a shared example group
+    Given a file named "shared_example_group_params_spec.rb" with:
+    """
+    shared_examples_for "a measurable object" do |measurement_method, measurement|
+      it "should return #{measurement} from ##{measurement_method}" do
+        subject.send(measurement_method).should == measurement
+      end
+    end
+
+    describe Array, "with 3 items" do
+      subject { [1, 2, 3] }
+      it_should_behave_like "a measurable object", :size, 3
+    end
+
+    describe String, "of 6 characters" do
+      subject { "FooBar" }
+      it_should_behave_like "a measurable object", :length, 6
+    end
+    """
+    When I run "rspec shared_example_group_params_spec.rb --format documentation"
+    Then the output should contain "2 examples, 0 failures"
+    And the output should contain:
+      """
+      Array with 3 items
+        it should behave like a measurable object
+          should return 3 from #size
+
+      String of 6 characters
+        it should behave like a measurable object
+          should return 6 from #length
+      """
+
   Scenario: Aliasing "it_should_behave_like" to "it_has_behavior"
     Given a file named "shared_example_group_spec.rb" with:
       """

lib/rspec/core/example_group.rb

@@ -60,12 +60,12 @@ class << self
 
       def self.define_shared_group_method(new_name, report_label=nil)
         module_eval(<<-END_RUBY, __FILE__, __LINE__)
-          def self.#{new_name}(name, &customization_block)
+          def self.#{new_name}(name, *args, &customization_block)
             shared_block = world.shared_example_groups[name]
             raise "Could not find shared example group named \#{name.inspect}" unless shared_block
 
             describe("#{report_label || "it should behave like"} \#{name}") do
-              module_eval &shared_block
+              module_exec *args, &shared_block
               module_eval &customization_block if customization_block
             end
           end

spec/rspec/core/shared_example_group_spec.rb

@@ -80,6 +80,26 @@ def self.foo; end
         shared_group.methods.map{|m| m.to_s}.should include("foo")
       end
 
+      context "given some parameters" do
+        it "passes the parameters to the shared example group" do
+          passed_params = {}
+
+          shared_examples_for("thing") do |param1, param2|
+            it("has access to the given parameters") do
+              passed_params[:param1] = param1
+              passed_params[:param2] = param2
+            end
+          end
+
+          group = ExampleGroup.describe("group") do
+            it_should_behave_like "thing", :value1, :value2
+          end
+          group.run_all
+
+          passed_params.should == { :param1 => :value1, :param2 => :value2 }
+        end
+      end
+
       context "given a block" do
         it "evaluates the block in nested group" do
           scopes = []