Merge Pysch 3.0.3.pre1.

I added the following additional commits from 3.0.3.pre1:
    * https://github.com/ruby/psych/pull/356
    * https://github.com/ruby/psych/pull/357
    * https://github.com/ruby/psych/pull/359

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@63280 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/psych/test_psych.rb

@@ -144,12 +144,49 @@ class TestPsych < Psych::TestCase
     }
   end
 
+  def test_load_file_default_return_value
+    Tempfile.create(['empty', 'yml']) {|t|
+      assert_equal false, Psych.load_file(t.path)
+    }
+  end
+
   def test_load_file_with_fallback
+    Tempfile.create(['empty', 'yml']) {|t|
+      assert_equal 42, Psych.load_file(t.path, fallback: 42)
+    }
+  end
+
+  def test_load_file_with_fallback_nil_or_false
+    Tempfile.create(['empty', 'yml']) {|t|
+      assert_nil Psych.load_file(t.path, fallback: nil)
+      assert_equal false, Psych.load_file(t.path, fallback: false)
+    }
+  end
+
+  def test_load_file_with_fallback_hash
     Tempfile.create(['empty', 'yml']) {|t|
       assert_equal Hash.new, Psych.load_file(t.path, fallback: Hash.new)
     }
   end
 
+  def test_load_file_with_fallback_for_nil
+    Tempfile.create(['nil', 'yml']) {|t|
+      t.binmode
+      t.write('--- null')
+      t.close
+      assert_nil Psych.load_file(t.path, fallback: 42)
+    }
+  end
+
+  def test_load_file_with_fallback_for_false
+    Tempfile.create(['false', 'yml']) {|t|
+      t.binmode
+      t.write('--- false')
+      t.close
+      assert_equal false, Psych.load_file(t.path, fallback: 42)
+    }
+  end
+
   def test_parse_file
     Tempfile.create(['yikes', 'yml']) {|t|
       t.binmode

test/psych/test_stream.rb

@@ -3,6 +3,22 @@ require_relative 'helper'
 
 module Psych
   class TestStream < TestCase
+    [
+      [Psych::Nodes::Alias, :alias?],
+      [Psych::Nodes::Document, :document?],
+      [Psych::Nodes::Mapping, :mapping?],
+      [Psych::Nodes::Scalar, :scalar?],
+      [Psych::Nodes::Sequence, :sequence?],
+      [Psych::Nodes::Stream, :stream?],
+    ].each do |klass, block|
+      define_method :"test_predicate_#{block}" do
+        rb = Psych.parse_stream("---\n- foo: bar\n- &a !!str Anchored\n- *a")
+        nodes = rb.grep(klass)
+        assert_operator nodes.length, :>, 0
+        assert_equal nodes, rb.find_all(&block)
+      end
+    end
+
     def test_parse_partial
       rb = Psych.parse("--- foo\n...\n--- `").to_ruby
       assert_equal 'foo', rb