Last updated: May 31, 26 01:31 UTC | Permalink

3 - When Have I Written Enough Tests?

Learning Objectives:

After this lecture, you will be able to:

• Explain how TypeScript types and documented preconditions influence what tests you need to write
• Explain the difference between the any and unknown types in TypeScript
• Understand the structure of a simple Express server incorporating Zod validation
• Explain what code coverage is, and how different measures differ, including statements, branches, functions, and lines
• Explain the benefits of mutation testing

Important Dates:

• Individual Project 1 Due Wednesday, May 13 by 6pm (ET)

Lecture Slides:

• Trusting Typescript (Or Not) Slides PDF, PPT
• Code Coverage & Mutation Testing Slides PDF, PPT

Activities

• Activity 3.1: Messing With APIs
• Activity 3.2: Mutation Testing with Stryker

Tutorials

• Getting Started with TypeScript
• Guide to API Requests and Installing Postman

Resources

• Working with JSON
• Zod documentation
• Software Engineering at Google: “Testing”
• StrykerJS - Mutation Testing Tool
• Are mutants a valid substitute for real faults in software testing?
• Go Testing By Example, by Rob Pike — source of the “Coverage is no substitute for thought” quote from the slides with a lot of good and general advice about testing