Before considering the application complete, verify the following scenarios.

Project setup

• Node.js starts successfully.
• Environment variables load correctly.
• MongoDB connects successfully.

CRUD operations

• Create a user.
• Retrieve all users.
• Retrieve a user by ID.
• Update a user.
• Partially update a user.
• Delete a user.

Authentication

• Register a user.
• Verify password hashing.
• Log in with valid credentials.
• Reject invalid credentials.
• Reject expired access tokens.
• Reject malformed tokens.

Authorization

• Reject unauthenticated requests.
• Reject unauthorized roles.
• Prevent users from accessing another user's private resources.

Validation

• Reject missing fields.
• Reject invalid email addresses.
• Reject invalid ObjectIds.
• Reject unexpected properties.

Performance and security

• Verify indexes.
• Test pagination.
• Test filtering and sorting.
• Verify rate limiting.
• Verify secure error responses.

Deployment

• Build Docker image.
• Start the container.
• Verify health endpoints.
• Verify production database connectivity.

Completing these checks provides a strong foundation for a production-oriented REST API.