Modularize app structure

app/__init__.py

@@ -4,17 +4,19 @@
 from dotenv import load_dotenv
 from flask import Flask
 
-app = Flask(__name__)
+def create_app():
+    """Application factory pattern."""
+    # Load the env variables to use here
+    load_dotenv()
 
-# Use app.config to set config connection details
-load_dotenv()
-app.config['MONGO_URI'] = os.getenv('MONGO_CONNECTION')
-app.config['DB_NAME'] = os.getenv('PROJECT_DATABASE')
-app.config['COLLECTION_NAME'] = os.getenv('PROJECT_COLLECTION')
+    app = Flask(__name__)
+    # Use app.config to set config connection details
+    app.config['MONGO_URI'] = os.getenv('MONGO_CONNECTION')
+    app.config['DB_NAME'] = os.getenv('PROJECT_DATABASE')
+    app.config['COLLECTION_NAME'] = os.getenv('PROJECT_COLLECTION')
 
-# Import routes — routes can import app safely because it exists
-from app.routes import register_routes # pylint: disable=wrong-import-position
-register_routes(app)
+    # Import routes — routes can import app safely because it exists
+    from app.routes import register_routes # pylint: disable=import-outside-toplevel
+    register_routes(app)
 
-# Expose `app` for importing
-__all__ = ["app"]
+    return app

app/routes.py

@@ -68,7 +68,8 @@ def add_book():
         # Send the host and new book_id to the helper function to generate links
         book_for_response = append_hostname(new_book, host)
         print("book_for_response", book_for_response)
-        # Remove MOngoDB's ObjectID value
+
+        # Remove MongoDB's ObjectID value
         book_for_response.pop('_id', None)
 
         return jsonify(book_for_response), 201

app/utils/helper.py

@@ -1,4 +1,4 @@
-""" Collection of helper fucntions """
+""" Collection of helper functions """
 
 from urllib.parse import urljoin
 

run.py

@@ -0,0 +1,8 @@
+"""Entry point for running the Flask application.
+
+This script imports the Flask application factory from the app package,
+creates an instance of the application, and runs it in debug mode.
+"""
+from app import create_app
+
+app = create_app()

tests/test_app.py

@@ -1,18 +1,17 @@
 # pylint: disable=missing-docstring
 
-# Filepath is this: /Users/Shanti.Rai@methods.co.uk/Documents/S_BookAPIV.2/tests/test_app.py
-
 from unittest.mock import patch
 from pymongo.errors import ServerSelectionTimeoutError
 import pytest
 from app.datastore.mongo_db import get_book_collection
-from app import app
+from app import create_app
 
 
 # Option 1: Rename the fixture to something unique (which I've used)
 # Option 2: Use a linter plugin that understands pytest
 @pytest.fixture(name="client")
 def client_fixture():
+    app = create_app()
     app.config['TESTING'] = True
     return app.test_client()
 
@@ -561,6 +560,7 @@ def test_get_book_collection_handles_connection_failure():
         # Set the side effect to raise a ServerSelectionTimeoutError
         mock_client.side_effect = ServerSelectionTimeoutError("Mock Connection Timeout")
 
+        app = create_app()
         with app.app_context():   # <-- Push the app context here
             with pytest.raises(Exception) as exc_info:
                 get_book_collection()

tests/test_integration.py

@@ -1,12 +1,13 @@
 # pylint: disable=missing-docstring
 import pytest
 from pymongo import MongoClient
-from app import app
+from app import create_app
 
 
 @pytest.fixture(name="client")
 def client_fixture():
     """Provides a test client for making requests to our Flask app."""
+    app = create_app()
     app.config['TESTING'] = True
     app.config['MONGO_URI'] = 'mongodb://localhost:27017/'
     app.config['DB_NAME'] = 'test_database'

tests/test_mongo_helper.py

@@ -1,6 +1,5 @@
 # pylint: disable=missing-docstring
 
-# Filepath: #/Users/Shanti.Rai@methods.co.uk/Documents/S_BookAPIV.2/app/datastore/mongo_helper.p
 from unittest.mock import MagicMock
 from app.datastore.mongo_helper import insert_book_to_mongo