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basic TypeScript • basic Jest
skills learned
dynamically configure Nest.js containers • mock an HTTPservice dependency
Daniel Coleman and Max Guernsey, III
1 week · 4-6 hours per week · INTERMEDIATE

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Ensure your system can accommodate even unstable dependency services. You’re a TypeScript developer for a large company that sells stock photography. You’re responsible for the service that ingests images. Unfortunately, the ingestion process is being negatively affected by a flaky external web service that the ingestion engine uses, and the problem is not reproducible in unit testing since there’s no connection to the external service at that time. Working in IntelliJ WebStorm, you’ll establish an in-memory HTTP service, configure it to simulate a dependency service, write a test to reproduce the error, and use the test to build robustness into your system.

This project is designed for learning purposes and is not a complete, production-ready application or solution.

project authors

Daniel Coleman

Daniel Coleman has been writing software since he was twelve years old, and has been getting paid for it for the last ten years. He quickly progressed from individual contributor to trailblazer for software design excellence, turning his teammates into fellow disciples of high quality. Dan has also worked as an embedded coach for teams, helping them perfect their craft through best practices for code design, test-driven development, behavior-driven development, and effective requirements management. He shares his thoughts on the industry and software design at agiledesign.io.

Max Guernsey, III

Max Guernsey has over twenty years of experience in software development and is currently a managing member at DevCraft LLC. He has worked on a wide range of products and technologies, including C++ class libraries, financial analysis applications, C# and Java backends, and even multi-platform video games. He is an experienced consultant and his "coaching from the keyboard" approach provides hands-on experience to learners in all aspects of modern software development.


This liveProject is for developers with an intermediate-level understanding of TypeScript and object-oriented design. To begin these liveProjects you’ll need to be familiar with the following:

  • Basic Jest
  • Basic Nest.js
  • Basic Node.js
  • Basic Axios
  • Working knowledge of TypeScript 4.x
  • Working knowledge of object-oriented programming


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