from engine.effects.legacy import vis_offset, vis_trunc


def test_vis_offset_no_change():
    """vis_offset with offset 0 returns original."""
    result = vis_offset("hello", 0)
    assert result == "hello"


def test_vis_offset_trims_start():
    """vis_offset skips first N characters."""
    result = vis_offset("hello world", 6)
    assert result == "world"


def test_vis_offset_handles_ansi():
    """vis_offset handles ANSI codes correctly."""
    result = vis_offset("\033[31mhello\033[0m", 3)
    assert result == "lo\x1b[0m" or "lo" in result


def test_vis_offset_greater_than_length():
    """vis_offset with offset > length returns empty-ish."""
    result = vis_offset("hi", 10)
    assert result == ""


def test_vis_trunc_still_works():
    """Ensure vis_trunc still works after changes."""
    result = vis_trunc("hello world", 5)
    assert result == "hello"