Rework core functionality, add CLI and tests

tests/conftest.py

@@ -0,0 +1,70 @@
+"""
+Test configuration and fixtures for HXBooks.
+
+Provides isolated test database, Flask app instances, and CLI testing utilities.
+"""
+
+import tempfile
+from pathlib import Path
+from typing import Generator
+
+import pytest
+from click.testing import CliRunner
+from flask import Flask
+from flask.testing import FlaskClient
+
+from hxbooks import cli, create_app
+from hxbooks.db import db
+from hxbooks.models import User
+
+
+@pytest.fixture
+def app(tmp_path: Path, monkeypatch: pytest.MonkeyPatch) -> Flask:
+    """Create Flask app with test configuration."""
+    test_db_path = tmp_path / "test.db"
+    test_config = {
+        "TESTING": True,
+        "SQLALCHEMY_DATABASE_URI": f"sqlite:///{test_db_path}",
+        "SECRET_KEY": "test-secret-key",
+        "WTF_CSRF_ENABLED": False,
+    }
+
+    app = create_app(test_config)
+
+    with app.app_context():
+        db.create_all()
+
+    monkeypatch.setattr(cli, "get_app", lambda: app)
+    return app
+
+
+@pytest.fixture
+def client(app: Flask) -> FlaskClient:
+    """Create test client for Flask app."""
+    return app.test_client()
+
+
+@pytest.fixture
+def cli_runner() -> CliRunner:
+    """Create Click CLI test runner."""
+    return CliRunner()
+
+
+@pytest.fixture
+def test_user(app: Flask) -> User:
+    """Create a test user in the database."""
+    with app.app_context():
+        user = User(username="testuser")
+        db.session.add(user)
+        db.session.commit()
+
+        # Refresh to get the ID
+        db.session.refresh(user)
+        return user
+
+
+@pytest.fixture
+def db_session(app: Flask):
+    """Create database session for direct database testing."""
+    with app.app_context():
+        yield db.session