feat(taskflow): add core task API, storage persistence, csv export, stats page, and test coverage

tests/test_domain_tasks.py

@@ -0,0 +1,96 @@
+from __future__ import annotations
+
+from datetime import UTC, datetime, timedelta
+from uuid import uuid4
+
+import pytest
+
+from app.domain import InvalidTransitionError, complete_task, start_task
+from app.storage import StoredTask
+
+
+def make_task(
+    *,
+    title: str = "Task",
+    started_at: datetime | None = None,
+    done_at: datetime | None = None,
+) -> StoredTask:
+    return StoredTask(
+        id=uuid4(),
+        title=title,
+        created_at=datetime.now(UTC),
+        started_at=started_at,
+        done_at=done_at,
+    )
+
+
+def test_start_task_from_backlog_sets_started_at():
+    task = make_task(started_at=None, done_at=None)
+    before_call = datetime.now(UTC)
+
+    result = start_task(task)
+
+    after_call = datetime.now(UTC)
+
+    assert result.id == task.id
+    assert result.title == task.title
+    assert result.created_at == task.created_at
+    assert result.done_at is None
+    assert result.started_at is not None
+    assert before_call <= result.started_at <= after_call
+
+
+def test_start_task_is_idempotent_for_already_started_task():
+    started_at = datetime.now(UTC) - timedelta(minutes=5)
+    task = make_task(started_at=started_at, done_at=None)
+
+    result = start_task(task)
+
+    assert result == task
+    assert result.started_at == started_at
+
+
+def test_start_task_raises_for_completed_task():
+    started_at = datetime.now(UTC) - timedelta(minutes=10)
+    done_at = datetime.now(UTC) - timedelta(minutes=1)
+    task = make_task(started_at=started_at, done_at=done_at)
+
+    with pytest.raises(InvalidTransitionError, match="invalid_transaction"):
+        start_task(task)
+
+
+def test_complete_task_from_in_progress_sets_done_at():
+    started_at = datetime.now(UTC) - timedelta(minutes=10)
+    task = make_task(started_at=started_at, done_at=None)
+    before_call = datetime.now(UTC)
+
+    result = complete_task(task)
+
+    after_call = datetime.now(UTC)
+
+    assert result.id == task.id
+    assert result.title == task.title
+    assert result.created_at == task.created_at
+    assert result.started_at == started_at
+    assert result.done_at is not None
+    assert result.started_at <= result.done_at
+    assert before_call <= result.done_at <= after_call
+
+
+def test_complete_task_is_idempotent_for_already_completed_task():
+    started_at = datetime.now(UTC) - timedelta(minutes=10)
+    done_at = datetime.now(UTC) - timedelta(minutes=1)
+    task = make_task(started_at=started_at, done_at=done_at)
+
+    result = complete_task(task)
+
+    assert result == task
+    assert result.done_at == done_at
+
+
+def test_complete_task_raises_for_backlog_task():
+    task = make_task(started_at=None, done_at=None)
+
+    with pytest.raises(InvalidTransitionError, match="invalid_transaction"):
+        complete_task(task)
+