public void CopyTo()
{
var buffer = new BufferReaderWriter(new byte[10], 0, 0, false);
buffer.WriteByte(1);
buffer.Seek(0, SeekOrigin.End);
buffer.WriteByte(2);
var arr = new byte[10];
buffer.CopyTo(arr, 0);
Assert.Equal(new byte[] { 1, 0, 0, 0, 0, 0, 0, 0, 0, 2 }, arr);
Assert.Throws <InvalidOperationException>(() => buffer.CopyTo(arr, -1));
arr = new byte[9];
Assert.Throws <InvalidOperationException>(() => buffer.CopyTo(arr, 0));
arr = new byte[12];
buffer.CopyTo(arr, 2);
Assert.Equal(new byte[] { 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2 }, arr);
buffer = new BufferReaderWriter(new byte[10] {
1, 2, 3, 4, 5, 6, 7, 8, 9, 10
});
arr = new byte[8];
buffer.CopyTo(arr, 0, 2);
Assert.Equal(new byte[] { 3, 4, 5, 6, 7, 8, 9, 10 }, arr);
}