LlamaIndex is a framework designed to enhance large language model (LLM) applications by incorporating domain-specific data, allowing users to create customized tools such as question-answering chatbots and document-understanding applications. This tutorial guides users through building a retrieval-augmented generation (RAG) question-answering system using LlamaIndex, with the system's functionality exposed as a REST API via Flask. It includes steps for setting up a Python development environment, configuring continuous integration with CircleCI, and writing unit tests using pytest. The tutorial uses a Paul Graham essay as input data but allows for customization with other data sources, and it provides a comprehensive guide to automating testing processes to ensure efficient development. The complete source code is available on GitHub for further exploration and implementation.