diff --git a/ruby/test_case.rb b/ruby/test_case.rb
new file mode 100644
index 0000000..af6d160
--- /dev/null
+++ b/ruby/test_case.rb
@@ -0,0 +1,142 @@
+require 'test/unit'
+require 'msgpack'
+
+class MessagePackTestFormat < Test::Unit::TestCase
+	def self.it(name, &block)
+		define_method("test_#{name}", &block)
+	end
+
+	it "nil" do
+		check 1, nil
+	end
+
+	it "true" do
+		check 1, true
+	end
+
+	it "false" do
+		check 1, false
+	end
+
+	it "zero" do
+		check 1, 0
+	end
+
+	it "positive fixnum" do
+		check 1, 1
+		check 1, (1<<6)
+		check 1, (1<<7)-1
+	end
+
+	it "positive int 8" do
+		check 1, -1
+		check 2, (1<<7)
+		check 2, (1<<8)-1
+	end
+
+	it "positive int 16" do
+		check 3, (1<<8)
+		check 3, (1<<16)-1
+	end
+
+	it "positive int 32" do
+		check 5, (1<<16)
+		check 5, (1<<32)-1
+	end
+
+	it "positive int 64" do
+		check 9, (1<<32)
+		check 9, (1<<64)-1
+	end
+
+	it "negative fixnum" do
+		check 1, -1
+		check 1, -((1<<5)-1)
+		check 1, -(1<<5)
+	end
+
+	it "negative int 8" do
+		check 2, -((1<<5)+1)
+		check 2, -(1<<7)
+	end
+
+	it "negative int 16" do
+		check 3, -((1<<7)+1)
+		check 3, -(1<<15)
+	end
+
+	it "negative int 32" do
+		check 5, -((1<<15)+1)
+		check 5, -(1<<31)
+	end
+
+	it "negative int 64" do
+		check 9, -((1<<31)+1)
+		check 9, -(1<<63)
+	end
+
+	it "fixraw" do
+		check_raw 1, 0
+		check_raw 1, (1<<5)-1
+	end
+
+	it "raw 16" do
+		check_raw 3, (1<<5)
+		check_raw 3, (1<<16)-1
+	end
+
+	it "raw 32" do
+		check_raw 5, (1<<16)
+		#check_raw 5, (1<<32)-1  # memory error
+	end
+
+	it "fixarray" do
+		check_array 1, 0
+		check_array 1, (1<<4)-1
+	end
+
+	it "array 16" do
+		check_array 3, (1<<4)
+		check_array 3, (1<<16)-1
+	end
+
+	it "array 32" do
+		check_array 5, (1<<16)
+		#check_array 5, (1<<32)-1  # memory error
+	end
+
+#	it "fixmap" do
+#		check_map 1, 0
+#		check_map 1, (1<<4)-1
+#	end
+#
+#	it "map 16" do
+#		check_map 3, (1<<4)
+#		check_map 3, (1<<16)-1
+#	end
+#
+#	it "map 32" do
+#		check_map 5, (1<<16)
+#		#check_map 5, (1<<32)-1  # memory error
+#	end
+
+	private
+	def check(len, obj)
+		v = obj.to_msgpack
+		assert_equal(v.length, len)
+		assert_equal(MessagePack.unpack(v), obj)
+	end
+
+	def check_raw(overhead, num)
+		check num+overhead, " "*num
+	end
+
+	def check_array(overhead, num)
+		check num+overhead, Array.new(num)
+	end
+
+	def check_map(overhead, num)
+		# FIXME
+	end
+end
+