Complete mongo db integration for get /books/{id})

[codesungrape]

Description

Trello ticket: https://trello.com/c/O9jraVyM

This change finalizes the transition of the GET /books/{id} endpoint. The endpoint now retrieves book details directly from the MongoDB database using a find_one() query, replacing the previous in-memory or mock implementation. It includes an updated, comprehensive test suite to achieve 100% test coverage for the new logic.

Type of change

Please delete options that are not relevant.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update
• Code refactor (improving code quality without changing functionality)
• Performance improvement
• Other (please describe):

How Has This Been Tested?

Automated tests, manual testing, cURL, CI/CD pipeline

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• My individual commit messages are descriptive and follow our commit guidelines
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules

[Copilot]

Pull Request Overview

This PR completes the MongoDB integration for the GET /books/{id} endpoint, transitioning from an in-memory implementation to a database-backed solution. The endpoint now queries MongoDB directly using ObjectId validation and proper error handling.

• Replace in-memory book lookup with MongoDB collection.find_one() queries
• Add ObjectId validation for book IDs with appropriate 400 error responses
• Implement comprehensive test suite with both unit and integration tests covering all error scenarios

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

File	Description
app/routes.py	Replaces in-memory book lookup with MongoDB queries, adds ObjectId validation and proper error handling
tests/test_app.py	Adds comprehensive test coverage with unit tests using mocks and integration tests with real database operations
tests/conftest.py	Introduces db_setup fixture for clean database state management in tests
openapi.yml	Updates API documentation to reflect new error responses (400, 404, 500) with proper schemas

[Copilot]

[nitpick] The pylint disable comment for line-too-long is unnecessary. The line is well within reasonable limits and the comment adds clutter.

Suggested change

	) # pylint: disable=line-too-long
	)

[Copilot]

[nitpick] This function is missing a blank line before the function definition, which is inconsistent with the formatting of other test functions in the file.

Suggested change

[Copilot]

Consider adding exception handling around the MongoDB query. Database operations can raise exceptions (ConnectionFailure, ServerSelectionTimeoutError) that should be caught and converted to appropriate HTTP error responses.

[Copilot]

[nitpick] The comment 'also equivalent to Key version' is unclear and doesn't add value. Consider removing it or making it more descriptive.

Suggested change

	# also equivalent to Key version
	# book = raw_books.find_one(_id=obj_id, state={"$ne": "deleted"})
	# Alternative query to fetch a non-deleted book by its ID
	# book = collection.find_one({"_id": obj_id, "state": {"$ne": "deleted"}})

[Copilot]

This commented-out code should be removed as it serves no purpose and adds confusion. The variable name 'raw_books' doesn't match the actual collection variable name.

Suggested change

# book = raw_books.find_one(_id=obj_id, state={"$ne": "deleted"})