Add in-tree mspec and ruby/spec

* For easier modifications of ruby/spec by MRI developers.
* .gitignore: track changes under spec.
* spec/mspec, spec/rubyspec: add in-tree mspec and ruby/spec.
  These files can therefore be updated like any other file in MRI.
  Instructions are provided in spec/README.
  [Feature #13156] [ruby-core:79246]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@58595 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

spec/rubyspec/shared/enumerator/with_object.rb

@@ -0,0 +1,42 @@
+require File.expand_path('../../../spec_helper', __FILE__)
+
+describe :enum_with_object, shared: true do
+  before :each do
+    @enum = [:a, :b].to_enum
+    @memo = ''
+    @block_params = @enum.send(@method, @memo).to_a
+  end
+
+  it "receives an argument" do
+    @enum.method(@method).arity.should == 1
+  end
+
+  context "with block" do
+    it "returns the given object" do
+      ret = @enum.send(@method, @memo) do |elm, memo|
+        # nothing
+      end
+      ret.should equal(@memo)
+    end
+
+    context "the block parameter" do
+      it "passes each element to first parameter" do
+        @block_params[0][0].should equal(:a)
+        @block_params[1][0].should equal(:b)
+      end
+
+      it "passes the given object to last parameter" do
+        @block_params[0][1].should equal(@memo)
+        @block_params[1][1].should equal(@memo)
+      end
+    end
+  end
+
+  context "without block" do
+    it "returns new Enumerator" do
+      ret = @enum.send(@method, @memo)
+      ret.should be_an_instance_of(Enumerator)
+      ret.should_not equal(@enum)
+    end
+  end
+end