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/socket/unixsocket/peeraddr_spec.rb

@@ -0,0 +1,30 @@
+require File.expand_path('../../../../spec_helper', __FILE__)
+require File.expand_path('../../fixtures/classes', __FILE__)
+
+describe "UNIXSocket#peeraddr" do
+
+  platform_is_not :windows do
+    before :each do
+      @path = SocketSpecs.socket_path
+      rm_r @path
+
+      @server = UNIXServer.open(@path)
+      @client = UNIXSocket.open(@path)
+    end
+
+    after :each do
+      @client.close
+      @server.close
+      rm_r @path
+    end
+
+    it "returns the address familly and path of the server end of the connection" do
+      @client.peeraddr.should == ["AF_UNIX", @path]
+    end
+
+    it "raises an error in server sockets" do
+      lambda { @server.peeraddr }.should raise_error
+    end
+  end
+
+end