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/unit/application/test_open_study_session.py

@@ -7,6 +7,7 @@ import pytest
 from flash_card.application.dto.card_dto import CardDto
 from flash_card.application.use_cases.open_study_session import open_study_session
 from flash_card.domain.entities.card import Card
+from flash_card.domain.entities.deck import Deck
 from flash_card.domain.entities.vocabulary import Vocabulary
 from flash_card.domain.errors.vocabulary_errors import VocabularyNotFoundError
 from flash_card.domain.value_objects.language_pair import LanguagePair
@@ -20,6 +21,18 @@ class _FakeRepository:
         return self._vocabulary
 
 
+class _RecordingProgress:
+    def __init__(self, stored: Deck | None = None) -> None:
+        self.stored = stored
+        self.saved: list[tuple[Card, ...]] = []
+
+    def load(self) -> Deck | None:
+        return self.stored
+
+    def save(self, deck: Deck) -> None:
+        self.saved.append(deck.cards)
+
+
 class _MissingRepository:
     def load(self) -> Vocabulary:
         raise VocabularyNotFoundError("missing")
@@ -33,7 +46,7 @@ def test_open_study_session_builds_session_over_all_cards() -> None:
     cards = (Card("aku", "mig"), Card("kau", "du"))
     repository = _FakeRepository(Vocabulary(LanguagePair("ms", "da"), cards))
 
-    session = open_study_session(repository, _first)
+    session = open_study_session(repository, _RecordingProgress(), _first)
 
     assert session.remaining == 2
     assert session.next_card() == CardDto("aku", "mig", "ms", "da")
@@ -41,4 +54,33 @@ def test_open_study_session_builds_session_over_all_cards() -> None:
 
 def test_open_study_session_propagates_repository_error() -> None:
     with pytest.raises(VocabularyNotFoundError):
-        open_study_session(_MissingRepository(), _first)
+        open_study_session(_MissingRepository(), _RecordingProgress(), _first)
+
+
+def test_open_study_session_prefers_saved_progress() -> None:
+    pair = LanguagePair("ms", "da")
+    vocabulary = Vocabulary(pair, (Card("aku", "mig"), Card("kau", "du")))
+    progress = _RecordingProgress(Deck(pair, [Card("kau", "du")]))
+
+    session = open_study_session(_FakeRepository(vocabulary), progress, _first)
+
+    assert session.remaining == 1
+    assert session.next_card() == CardDto("kau", "du", "ms", "da")
+
+
+def test_open_study_session_skips_vocabulary_when_progress_exists() -> None:
+    progress = _RecordingProgress(Deck(LanguagePair("ms", "da"), []))
+
+    session = open_study_session(_MissingRepository(), progress, _first)
+
+    assert session.remaining == 0
+
+
+def test_open_study_session_never_saves_on_start() -> None:
+    vocabulary = Vocabulary(LanguagePair("ms", "da"), (Card("aku", "mig"),))
+    progress = _RecordingProgress()
+
+    session = open_study_session(_FakeRepository(vocabulary), progress, _first)
+    session.next_card()
+
+    assert progress.saved == []