"""Edge-case unit tests for _parse_range_header (PR #1290). The byte-range parser is security-relevant — malformed Range headers fromclients can cause off-by-one bugs, integer overflows, or info disclosureif not handled correctly per RFC 7233. The PR adds higher-level testsfor media inline streaming, but the range parser itself has no directunit tests. This file pins the parser's contract."""import pytest from api.routes import _parse_range_header  # Each tuple: (header, file_size, expected_result)# expected_result is None for invalid/unsatisfiable, or (start, end) inclusive.RANGE_CASES = [    # ── Valid ranges ─────────────────────────────────────────────────────    ("bytes=0-99", 1000, (0, 99), "explicit start-end"),    ("bytes=0-", 1000, (0, 999), "open-ended start"),    ("bytes=100-", 1000, (100, 999), "open-ended from middle"),    ("bytes=-500", 1000, (500, 999), "suffix range — last 500 bytes"),    ("bytes=-99999", 1000, (0, 999), "suffix > file_size clamps to start=0"),    ("bytes=0-99999", 1000, (0, 999), "end > file_size clamps to file_size-1"),    ("bytes=999-1500", 1000, (999, 999), "end past file clamps to last byte"),    ("bytes=100-100", 1000, (100, 100), "single-byte range"),    ("bytes=999-999", 1000, (999, 999), "last byte"),    ("bytes= 0-99", 1000, (0, 99), "whitespace inside trimmed"),    # ── Invalid → None (caller sends 416 Range Not Satisfiable) ─────────    ("", 1000, None, "empty header"),    ("bytes 0-100", 1000, None, "wrong format — space instead of ="),    ("bytes=", 1000, None, "no spec after ="),    ("bytes=-", 1000, None, "bare dash, no numbers"),    ("bytes=-0", 1000, None, "zero-length suffix"),    ("bytes=0-99,200-299", 1000, None, "multipart not supported"),    ("bytes=500-100", 1000, None, "reversed range"),    ("bytes=999999-", 1000, None, "start past file"),    ("bytes=abc-def", 1000, None, "non-numeric"),    ("bytes=-abc", 1000, None, "non-numeric suffix"),    (" bytes=0-99", 1000, None, "leading space — must startswith bytes="),    # ── Empty/zero file ─────────────────────────────────────────────────    ("bytes=0-99", 0, None, "empty file always None"),    # ── Negative numbers (should not yield negative offsets) ────────────    ("bytes=-1", 1000, (999, 999), "suffix=1 — last byte"),]  @pytest.mark.parametrize(    "header,file_size,expected,description",    RANGE_CASES,    ids=[c[3] for c in RANGE_CASES],)def test_parse_range_header(header, file_size, expected, description):    actual = _parse_range_header(header, file_size)    assert actual == expected, (        f"_parse_range_header({header!r}, {file_size}) = {actual!r}, "        f"expected {expected!r} — {description}"    )  # ── Invariants beyond the case table ────────────────────────────────────  def test_returned_offsets_are_non_negative_for_valid_inputs():    for header, file_size, expected, _ in RANGE_CASES:        if expected is None:            continue        start, end = _parse_range_header(header, file_size)        assert start >= 0, f"start must be non-negative: {start} from {header!r}"        assert end >= start, f"end must be >= start: ({start},{end}) from {header!r}"        assert end < file_size, (            f"end must be < file_size for valid range: {end} >= {file_size} "            f"from {header!r}"        )  def test_content_length_is_positive_for_valid_ranges():    """The (start, end) returned must always describe at least one byte —    otherwise _serve_file_bytes would compute Content-Length=0 incorrectly."""    for header, file_size, expected, _ in RANGE_CASES:        if expected is None:            continue        start, end = _parse_range_header(header, file_size)        content_length = end - start + 1        assert content_length >= 1, (            f"Valid range must have positive content-length, got {content_length} "            f"from {header!r} on size {file_size}"        )