MIL-005: Step 4 - Save progress

Review record RC-027 (Go, autonomous mode, not independent).

Task: MIL-005#1
Task: MIL-005#2
Task: MIL-005#3
Task: MIL-005#4
Task: MIL-005#5

tests/integration/test_progress_file.py

@@ -0,0 +1,96 @@
+"""Integration tests of saving and resuming progress over real CSV files."""
+
+from collections.abc import Callable, Sequence
+from pathlib import Path
+
+from flash_card.application.use_cases.open_study_session import open_study_session
+from flash_card.application.use_cases.study_session import StudySession
+from flash_card.domain.entities.card import Card
+from flash_card.infrastructure.persistence.csv_progress_repository import (
+    CsvProgressRepository,
+)
+from flash_card.infrastructure.persistence.csv_vocabulary_repository import (
+    CsvVocabularyRepository,
+)
+
+WORDS = "fr;en\nchaque;each\nparlé;speak\narrivé;come\n"
+
+Choose = Callable[[Sequence[Card]], Card]
+
+
+def _first(cards: Sequence[Card]) -> Card:
+    return cards[0]
+
+
+def _choose_front(front: str) -> Choose:
+    def choose(cards: Sequence[Card]) -> Card:
+        return next(card for card in cards if card.front == front)
+
+    return choose
+
+
+def _open(folder: Path, choose: Choose = _first) -> StudySession:
+    return open_study_session(
+        CsvVocabularyRepository(folder / "words.csv"),
+        CsvProgressRepository(folder / "words_to_learn.csv"),
+        choose,
+    )
+
+
+def _setup(folder: Path) -> Path:
+    (folder / "words.csv").write_text(WORDS, encoding="utf-8")
+    return folder / "words_to_learn.csv"
+
+
+def _text(path: Path) -> str:
+    return path.read_bytes().decode("utf-8-sig")
+
+
+def test_mark_known_writes_remaining_cards_in_order(tmp_path: Path) -> None:
+    progress = _setup(tmp_path)
+    session = _open(tmp_path, _choose_front("parlé"))
+    session.next_card()
+    session.mark_known()
+    assert _text(progress) == "fr;en\nchaque;each\narrivé;come\n"
+
+
+def test_restart_draws_only_from_progress_file(tmp_path: Path) -> None:
+    _setup(tmp_path)
+    first = _open(tmp_path, _choose_front("parlé"))
+    first.next_card()
+    first.mark_known()
+
+    second = _open(tmp_path)
+    fronts: set[str] = set()
+    for _ in range(6):
+        card = second.next_card()
+        assert card is not None
+        fronts.add(card.front_text)
+
+    assert second.remaining == 2
+    assert fronts == {"chaque", "arrivé"}
+
+
+def test_progress_file_is_readable_as_vocabulary(tmp_path: Path) -> None:
+    progress = _setup(tmp_path)
+    session = _open(tmp_path, _choose_front("chaque"))
+    session.next_card()
+    session.mark_known()
+    vocabulary = CsvVocabularyRepository(progress).load()
+    assert vocabulary.cards == (Card("parlé", "speak"), Card("arrivé", "come"))
+
+
+def test_header_only_progress_file_gives_finished_session(tmp_path: Path) -> None:
+    progress = _setup(tmp_path)
+    progress.write_text("fr;en\n", encoding="utf-8")
+    session = _open(tmp_path)
+    assert session.remaining == 0
+    assert session.next_card() is None
+
+
+def test_unknown_card_never_creates_progress_file(tmp_path: Path) -> None:
+    progress = _setup(tmp_path)
+    session = _open(tmp_path)
+    session.next_card()
+    session.next_card()
+    assert not progress.exists()