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/library/rexml/element/namespace_spec.rb

@@ -0,0 +1,27 @@
+require 'rexml/document'
+require File.expand_path('../../../../spec_helper', __FILE__)
+
+describe "REXML::Element#namespace" do
+  before :each do
+    @doc = REXML::Document.new("<a xmlns='1' xmlns:y='2'><b/><c xmlns:z='3'/></a>")
+    @elem = @doc.elements["//b"]
+  end
+
+  it "returns the default namespace" do
+    @elem.namespace.should == "1"
+  end
+
+  it "accepts a namespace prefix" do
+    @elem.namespace("y").should == "2"
+    @doc.elements["//c"].namespace("z").should == "3"
+  end
+
+  it "returns an empty String if default namespace is not defined" do
+    e = REXML::Document.new("<a/>")
+    e.root.namespace.should be_empty
+  end
+
+  it "returns nil if namespace is not defined" do
+    @elem.namespace("z").should be_nil
+  end
+end