from pathlib import Path
from unittest.mock import patch

from evanescere.services.thumbnail import select_character_overlay


def test_select_character_overlay_returns_none_for_empty_directory(tmp_path: Path):
    assert select_character_overlay(str(tmp_path)) is None


def test_select_character_overlay_filters_png_files(tmp_path: Path):
    first = tmp_path / "first.PNG"
    second = tmp_path / "second.png"
    first.write_bytes(b"")
    second.write_bytes(b"")
    (tmp_path / "notes.txt").write_text("ignore me")

    with patch("evanescere.services.thumbnail.random.choice", return_value=second) as choice:
        assert select_character_overlay(str(tmp_path)) == second

    assert choice.call_args.args[0] == [first, second]