tests/test_problems.py

"""The shipped problem-id whitelist (app/data/problem_ids.json).

Two properties matter and neither is about counting: the set has to be the real
canonical set (a regex would accept ids that do not exist), and the file must not
carry the ORACLE — era 2 removes statements and answers from the service path,
and this backend is the public face of the collab.
"""
from __future__ import annotations

import json

import pytest

from app.problems import DEFAULT_PATH, is_known_problem, problem_ids


def test_the_shipped_set_is_the_canonical_1669():
    ids = problem_ids()
    assert len(ids) == 1669
    counts = {
        prefix: sum(1 for i in ids if i.startswith(prefix + "_"))
        for prefix in ("normal", "hard1", "hard2", "hard3")
    }
    assert counts == {"normal": 1000, "hard1": 69, "hard2": 200, "hard3": 400}


def test_ids_that_only_match_the_grammar_are_not_in_the_set():
    """`^(normal|hard[123])_\\d{4}$` matches every one of these; the sets do
    not contain any of them. This is why the whitelist ships as data."""
    for absent in ("hard1_0070", "hard2_0201", "hard3_0401", "normal_1001", "normal_0000"):
        assert not is_known_problem(absent), absent
    for present in ("normal_0001", "normal_1000", "hard1_0069", "hard2_0141", "hard3_0400"):
        assert is_known_problem(present), present


def test_the_shipped_file_carries_no_statements_and_no_answers():
    doc = json.loads(DEFAULT_PATH.read_text())
    assert sorted(doc) == ["count", "ids", "provenance"]
    assert all(isinstance(i, str) for i in doc["ids"])
    # Provenance names the source and hashes it; it carries no problem content.
    assert sorted(doc["provenance"]["files"]) == [
        "hard1.jsonl", "hard2.jsonl", "hard3.jsonl", "normal.jsonl"
    ]
    for name, meta in doc["provenance"]["files"].items():
        assert len(meta["sha256"]) == 64, name


def test_an_overridden_path_is_honoured_and_a_broken_one_refuses_to_load(tmp_path):
    good = tmp_path / "ids.json"
    good.write_text(json.dumps({"count": 2, "ids": ["normal_0001", "hard2_0141"]}))
    assert problem_ids(str(good)) == frozenset({"normal_0001", "hard2_0141"})
    assert is_known_problem("hard2_0141", str(good))
    assert not is_known_problem("hard3_0400", str(good))

    # A set we cannot trust must never degrade to "accept everything".
    lying = tmp_path / "lying.json"
    lying.write_text(json.dumps({"count": 99, "ids": ["normal_0001"]}))
    with pytest.raises(ValueError):
        problem_ids(str(lying))

    empty = tmp_path / "empty.json"
    empty.write_text(json.dumps({"count": 0, "ids": []}))
    with pytest.raises(ValueError):
        problem_ids(str(empty))

    with pytest.raises(FileNotFoundError):
        problem_ids(str(tmp_path / "nope.json"))