import os

import feed_file_exporter as ffe
from constants import files as file_consts


def test_slice_rows_edge_cases():
    assert list(ffe.slice_rows([], 3)) == []
    assert list(ffe.slice_rows([1], 5)) == [[1]]
    assert list(ffe.slice_rows([1, 2, 3, 4], 2)) == [[1, 2], [3, 4]]
    assert list(ffe.slice_rows([1, 2, 3, 4, 5], 2)) == [[1, 2], [3, 4], [5]]


def test_write_rows_to_file_writes_correct_order(tmp_path):
    outdir = str(tmp_path)
    fn = 'sample.txt'
    rows = {
        'header': 'H',
        'body': ['B1', 'B2'],
        'tail': 'T',
    }
    path = ffe.write_rows_to_file(outdir, fn, rows)
    assert os.path.exists(path)
    with open(path, 'r', encoding='utf8') as f:
        content = f.read()
    expected = 'H' + file_consts.LINE_TERMINATOR
    expected += 'B1' + file_consts.LINE_TERMINATOR
    expected += 'B2' + file_consts.LINE_TERMINATOR
    expected += 'T'
    # Normalize line endings for robust assertion across platforms
    assert content.replace('\r\n', '\n') == expected.replace('\r\n', '\n')