public void Edit()
        {
            var dest = new MemoryStream();
            long size = 0;
            {
                var src1 = new MemoryStream();
                var obj  = new ContentDescriptionObject( null, 0 );
                foreach( var data in TestData )
                {
                    obj.Write( data.Key, data.Value );
                }

                obj.Save( src1, dest );
                dest.Seek( 0, SeekOrigin.Begin );
                size = obj.Size;
            }

            var header = new ObjectHeader( dest );
            var obj2   = new ContentDescriptionObject( dest, header.Size );

            Assert.AreEqual( size, dest.Length, "サイズ" );
            foreach( var data in TestData )
            {
                var value = obj2.Read( dest, data.Key );
                Assert.AreEqual( data.Value, value, "タグ情報" );
            }
        }
        /// <summary>
        /// テスト用の ContentDescriptionObject を生成します。
        /// </summary>
        /// <returns>オブジェクト。</returns>
        private static ContentDescriptionObject CreateTestObject()
        {
            var obj = new ContentDescriptionObject( null, 0 );
            foreach( var testValue in TestData )
            {
                obj.Write( testValue.Key, testValue.Value );
            }

            return obj;
        }