decomposer: generate deliverable files for Implement the task REST API service with FastAPI, including standard CRUD endpoints, HTTP status semantics, request and response models, and structured error handling.; Add a PostgreSQL persistence layer for the task service using SQLAlchemy models, session management, database initialization or migrations, and durable task storage integrated with the existing API contract.; Define and integrate Pydantic request and response schemas for task fields, status values, identifiers, timestamps, and validation errors across the existing FastAPI service and persistence contract.; Add automated pytest coverage for the task API, including CRUD behavior, request and response validation failures, HTTP status semantics, and persistence interactions using isolated test data.; Containerize the FastAPI task service and PostgreSQL persistence service with Docker Compose, including environment-based configuration, health checks, networking, startup dependencies, and persistent database storage.; Create project documentation and operational guidance covering local setup, Docker Compose configuration, environment variables, API endpoints, validation and error responses, testing commands, persistence behavior, and relevant best-practice notes.

tests/conftest.py

@@ -1 +1,27 @@
-# Env var setup that must run before app.config is imported.
+import pytest
+from fastapi.testclient import TestClient
+from sqlalchemy import create_engine
+from sqlalchemy.orm import sessionmaker
+
+from app.db import Base, get_db
+from app.main import app
+
+
+@pytest.fixture()
+def client(tmp_path):
+    engine = create_engine(f"sqlite:///{tmp_path}/test.db", connect_args={"check_same_thread": False})
+    Base.metadata.create_all(engine)
+    TestingSession = sessionmaker(bind=engine, expire_on_commit=False)
+
+    def override_db():
+        db = TestingSession()
+        try:
+            yield db
+        finally:
+            db.close()
+
+    app.dependency_overrides[get_db] = override_db
+    with TestClient(app) as test_client:
+        yield test_client
+    app.dependency_overrides.clear()
+    Base.metadata.drop_all(engine)

tests/test_tasks.py

@@ -0,0 +1,31 @@
+def test_crud_and_persistence(client):
+    response = client.post('/tasks', json={'title': 'Ship API', 'description': 'release it'})
+    assert response.status_code == 201
+    task = response.json()
+    assert task['status'] == 'pending'
+    task_id = task['id']
+
+    assert client.get('/tasks').status_code == 200
+    assert client.get(f'/tasks/{task_id}').json()['title'] == 'Ship API'
+    updated = client.patch(f'/tasks/{task_id}', json={'status': 'completed'}).json()
+    assert updated['status'] == 'completed'
+    assert client.delete(f'/tasks/{task_id}').status_code == 204
+    assert client.get(f'/tasks/{task_id}').status_code == 404
+
+
+def test_validation_and_status_semantics(client):
+    result = client.post('/tasks', json={'title': '   '})
+    assert result.status_code == 422
+    assert result.json()['error']['code'] == 'VALIDATION_ERROR'
+    assert client.post('/tasks', json={'title': 'x', 'status': 'unknown'}).status_code == 422
+    assert client.get('/tasks/not-a-uuid').status_code == 422
+    assert client.get('/tasks?limit=0').status_code == 422
+
+
+def test_filter_and_missing_resource(client):
+    client.post('/tasks', json={'title': 'one', 'status': 'completed'})
+    client.post('/tasks', json={'title': 'two', 'status': 'pending'})
+    response = client.get('/tasks?status=completed')
+    assert response.status_code == 200
+    assert len(response.json()) == 1
+    assert client.patch('/tasks/00000000-0000-0000-0000-000000000000', json={'title': 'x'}).status_code == 404