Legacy Code

you own this product
prerequisites
basic TypeScript • basic Jest
skills learned
derive tests from existing code • use mutation testing results to guide test efforts
Daniel Coleman and Max Guernsey, III
1 week · 6-8 hours per week · INTERMEDIATE
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Look inside

Your company sells stock photography products to the general public, as well as to news and other media markets. As the resident TypeScript developer, you’ve been tasked with maintaining and extending a class library for optimizing search results. You’ll set up tests to support refactoring of this legacy library, use “pinning tests” to extract a specification from the existing code, and generate a wide range of test coverage. You’ll learn to spot when and where to improve code maintainability, and set up mutation testing to ensure your tests catch unintended changes. By the end, you’ll have generated test coverage that supports refactoring, making future updates easy and painless.

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.

prerequisites

This liveProject is for TypeScript developers who want to improve their testing skills. To begin these liveProjects you’ll need to be familiar with the following:

TOOLS
  • Basic TypeScript
  • Basic Jest
TECHNIQUES
  • Object-oriented programming

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