public void GetPositionFromLineColumnTest()
{
var tb = new TextBufferMock("a\r\nb", "R");
int?position;
position = tb.GetPositionFromLineColumn(0, 0);
position.Should().Be(0);
position = tb.GetPositionFromLineColumn(1, 0);
position.Should().Be(3);
position = tb.GetPositionFromLineColumn(100, 100);
position.Should().NotHaveValue();
}