diff --git test/yaml/test_string.rb test/yaml/test_string.rb
new file mode 100644
index 0000000..26229a6
--- /dev/null
+++ test/yaml/test_string.rb
@@ -0,0 +1,45 @@
+require 'test/unit'
+require 'yaml'
+
+module YAML
+  class TestString < Test::Unit::TestCase
+    def test_binary_string_null
+      string = "\x00"
+      yml = YAML.dump string
+      assert_match(/binary/, yml)
+      assert_equal string, YAML.load(yml)
+    end
+
+    def test_binary_string
+      string = binary_string
+      yml = YAML.dump string
+      assert_match(/binary/, yml)
+      assert_equal string, YAML.load(yml)
+    end
+
+    def test_non_binary_string
+      string = binary_string(0.29)
+      yml = YAML.dump string
+      refute_match(/binary/, yml)
+      assert_equal string, YAML.load(yml)
+    end
+
+    def test_string_with_ivars
+      food = "is delicious"
+      ivar = "on rock and roll"
+      food.instance_variable_set(:@we_built_this_city, ivar)
+
+      str = YAML.load YAML.dump food
+      assert_equal ivar, food.instance_variable_get(:@we_built_this_city)
+    end
+
+    def binary_string percentage = 0.31, length = 100
+      string = ''
+      (percentage * length).to_i.times do |i|
+        string << "\b"
+      end
+      string << 'a' * (length - string.length)
+      string
+    end
+  end
+end
diff --git test/yaml/test_yaml_properties.rb test/yaml/test_yaml_properties.rb
new file mode 100644
index 0000000..48bb878
--- /dev/null
+++ test/yaml/test_yaml_properties.rb
@@ -0,0 +1,64 @@
+require 'test/unit'
+require 'yaml'
+
+module YAML
+  class TestYamlProperties < Test::Unit::TestCase
+    class Foo
+      attr_reader :a, :b, :c
+      def initialize
+        @a = 1
+        @b = 2
+        @c = 3
+      end
+
+      def to_yaml_properties
+        [:@a, :@b]
+      end
+    end
+
+    def test_object_dump_yaml_properties
+      foo = YAML.load(YAML.dump(Foo.new))
+      assert_equal 1, foo.a
+      assert_equal 2, foo.b
+      assert_nil foo.c
+    end
+
+    class Bar < Struct.new(:foo, :bar)
+      attr_reader :baz
+      def initialize *args
+        super
+        @baz = 'hello'
+      end
+
+      def to_yaml_properties
+        []
+      end
+    end
+
+    def test_struct_dump_yaml_properties
+      bar = YAML.load(YAML.dump(Bar.new('a', 'b')))
+      assert_equal 'a', bar.foo
+      assert_equal 'b', bar.bar
+      assert_nil bar.baz
+    end
+
+    def test_string_dump
+      string = "okonomiyaki"
+      class << string
+        def to_yaml_properties
+          [:@tastes]
+        end
+      end
+
+      string.instance_variable_set(:@tastes, 'delicious')
+      v = YAML.load YAML.dump string
+      assert_equal 'delicious', v.instance_variable_get(:@tastes)
+    end
+
+    def test_string_load
+      str = YAML.load("--- !str \nstr: okonomiyaki\n:@tastes: delicious\n")
+      assert_equal 'okonomiyaki', str
+      assert_equal 'delicious', str.instance_variable_get(:@tastes)
+    end
+  end
+end