* ext/psych/lib/psych.rb: Syck api compatibility [ruby-core:29157]

* ext/psych/lib/psych/nodes/node.rb: ditto
* test/psych/test_psych.rb: ditto

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@27134 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

ext/psych/lib/psych.rb

@@ -153,10 +153,15 @@ module Psych
   # Example:
   #
   #   Psych.dump(['a', 'b'])  # => "---\n- a\n- b\n"
-  def self.dump o, options = {}
+  def self.dump o, io = nil, options = {}
+    if Hash === io
+      options = io
+      io      = nil
+    end
+
     visitor = Psych::Visitors::YAMLTree.new options
     visitor << o
-    visitor.tree.to_yaml
+    visitor.tree.to_yaml io
   end
 
   ###

ext/psych/lib/psych/nodes/node.rb

@@ -30,10 +30,12 @@ module Psych
       # Convert this node to YAML.
       #
       # See also Psych::Visitors::Emitter
-      def to_yaml
-        io = StringIO.new
-        Visitors::Emitter.new(io).accept self
-        io.string
+      def to_yaml io = nil
+        real_io = io || StringIO.new
+
+        Visitors::Emitter.new(real_io).accept self
+        return real_io.string unless io
+        io
       end
     end
   end

test/psych/test_psych.rb

@@ -1,5 +1,8 @@
 require_relative 'helper'
 
+require 'stringio'
+require 'tempfile'
+
 class TestPsych < Psych::TestCase
   def test_dump_stream
     things = [22, "foo \n", {}]
@@ -7,6 +10,22 @@ class TestPsych < Psych::TestCase
     assert_equal things, Psych.load_stream(stream)
   end
 
+  def test_dump_file
+    hash = {'hello' => 'TGIF!'}
+    Tempfile.open('fun.yml') do |io|
+      assert_equal io, Psych.dump(hash, io)
+      io.rewind
+      assert_equal Psych.dump(hash), io.read
+    end
+  end
+
+  def test_dump_io
+    hash = {'hello' => 'TGIF!'}
+    stringio = StringIO.new ''
+    assert_equal stringio, Psych.dump(hash, stringio)
+    assert_equal Psych.dump(hash), stringio.string
+  end
+
   def test_simple
     assert_equal 'foo', Psych.load("--- foo\n")
   end