This repository contains practical exercises to learn how to use the different types of test doubles (dummies, stubs, spies, mocks and fakes) in multiple programming languages.

Features

Structured exercises: Two main katas to practice different types of test doubles
Multiple languages: Templates available in Java, TypeScript, Python, C#, Go and Kotlin
No libraries: Learn to create your own test doubles from scratch
Solutions included: Complete examples and solutions with Mockito in Java

Exercises

Random Number Kata

Implement a game where the player must guess a random number in three attempts. Ideal for practicing dummies and stubs.

Print Date Kata

Learn how to test a method that prints the current date. Perfect for practicing spies, strict mocks and fakes.

Technologies

Java (JUnit 5)
TypeScript (Jest)
Python (pytest)
C# (xUnit)
Go (testing)
Kotlin (JUnit 5)

Additional Resources

This project includes supplementary material used in talks and workshops:

📊 Presentation "Mock 101: The Art of Testing"
🎥 Talk at Codemotion 2024
🎥 Talk at T3chFest 2025

Mock 101: The Art of Testing