System.IO.Tests.StreamMethods.SeekTest C# (CSharp) Méthode

        public static void SeekTest(Stream stream, Boolean fSuppres)
        {
            long lngPos;
            byte btValue;

            stream.Position = 0;

            Assert.Equal(0, stream.Position);

            int length = 1 << 10; //fancy way of writing 2 to the pow 10
            byte[] btArr = new byte[length];
            for (int i = 0; i < btArr.Length; i++)
                btArr[i] = (byte)i;

            if (stream.CanWrite)
                stream.Write(btArr, 0, btArr.Length);
            else
                stream.Position = btArr.Length;

            Assert.Equal(btArr.Length, stream.Position);

            lngPos = stream.Seek(0, SeekOrigin.Begin);
            Assert.Equal(0, lngPos);

            Assert.Equal(0, stream.Position);

            for (int i = 0; i < btArr.Length; i++)
            {
                if (stream.CanWrite)
                {
                    btValue = (byte)stream.ReadByte();
                    Assert.Equal(btArr[i], btValue);
                }
                else
                {
                    stream.Seek(1, SeekOrigin.Current);
                }
                Assert.Equal(i + 1, stream.Position);
            }

            Assert.Throws<IOException>(() => stream.Seek(-5, SeekOrigin.Begin));

            lngPos = stream.Seek(5, SeekOrigin.Begin);
            Assert.Equal(5, lngPos);
            Assert.Equal(5, stream.Position);

            lngPos = stream.Seek(5, SeekOrigin.End);
            Assert.Equal(length + 5, lngPos);
            Assert.Throws<IOException>(() => stream.Seek(-(btArr.Length + 1), SeekOrigin.End));

            lngPos = stream.Seek(-5, SeekOrigin.End);
            Assert.Equal(btArr.Length - 5, lngPos);
            Assert.Equal(btArr.Length - 5, stream.Position);

            lngPos = stream.Seek(0, SeekOrigin.End);
            Assert.Equal(btArr.Length, stream.Position);

            for (int i = btArr.Length; i > 0; i--)
            {
                stream.Seek(-1, SeekOrigin.Current);
                Assert.Equal(i - 1, stream.Position);
            }

            Assert.Throws<IOException>(() => stream.Seek(-1, SeekOrigin.Current));
        }