Test-Driven Development in Java, JUnit, and Mockito | CodeSignal Learn

Skip to main content

intermediate

Test-Driven Development in Java, JUnit, and Mockito

Software Engineering

Trusted by learners working at top companies

Turn screen time into skills time

Practice anytime, anywhere with our mobile app.

Sign up

Join the 1M+ learners on CodeSignal

Be a part of our community of 1M+ users who develop and demonstrate their skills on CodeSignal

4 courses

99 practices

13 hours

Master TDD in Java using JUnit - write tests first, implement code, and refactor. Learn test doubles with the Mockito framework to isolate components. Create cleaner, more maintainable code while reducing bugs and improving development efficiency.

4.42

486 learners

Earn a shareable

Certificate of Achievement

Verified skills you'll gain

INTERMEDIATE

Computer Science Fundamentals

INTERMEDIATE

Programming, Algorithms, and Data Structures

Tools you'll use

Java

JUnit

Mockito

Course 1

Foundations of TDD in Java with JUnit: The Principles

6 lessons

27 practices

This course introduces Test-Driven Development (TDD) for Java projects, covering the Red-Green-Refactor workflow, TDD mindset, and setup with JUnit. Learn best practices like SOLID principles and dependency injection, and explore TDD's impact on code quality and speed compared to traditional approaches.

Course 2

Red-Green-Refactor: Practicing TDD with Java & JUnit

5 lessons

25 practices

This course focuses on practicing the core TDD workflow: "Red-Green-Refactor." You'll write failing tests (Red), implement code to pass them (Green), and refactor while keeping tests passing (Refactor). No new concepts are introduced—just hands-on practice with various requirements to sharpen your TDD skills.

Course 3

Isolating Dependencies with Test Doubles using JUnit & Mockito

5 lessons

26 practices

Discover the pivotal role of test doubles in modern software testing. This introductory course will guide you through the essentials of dummies, stubs, spies, mocks, and fakes. Learn how these powerful tools help you isolate units under test, control behavior, and build reliable, fast, and maintainable tests. Step into the world of test doubles and elevate your software development skills.

Course 4

Refactoring by Leveraging Tests with Java & JUnit

5 lessons

21 practices

This course focuses on the Refactor step in TDD, teaching developers to spot code smells and resolve them through refactoring. Using real-world examples, you'll identify common issues, apply refactoring techniques, and ensure functionality is preserved with existing tests.

Scan to download

Other paths you may like

Fundamental Coding Interview Prep with Python

Introduction to Programming with Python

Mastering Algorithms and Data Structures in Python

Advanced Coding Interview Preparation with Python

Full-Stack Engineering with JavaScript

Prompt Engineering for Everyone

Journey into Data Science with Python

Java Programming for Beginners

From our community

Hear what our customers have to say about CodeSignal Learn

I'm impressed by the quality and can't stop recommending it. It's also a lot of fun!

Francisco Aguilar Meléndez

Data Scientist

+11

I love that it's personalized. When I'm stuck, I don't have to hope my Google searches come out successful. The AI mentor Cosmo knows exactly what I need.

Faith Yim

Software Engineer

+14

It's an amazing product and exceeded my expectations, helping me prepare for my job interviews. Hands-on learning requires you to actually know what you are doing.

Alex Bush

Full Stack Engineer

+9

I'm really impressed by the AI tutor Cosmo's feedback about my code. It's honestly kind of insane to me that it's so targeted and specific.

Abbey Helterbran

Tech consultant

+8

I tried Leetcode but it was too disorganized. CodeSignal covers all the topics I'm interested in and is way more structured.

Jonathan Miller

Senior Machine Learning Engineer

+12

I'm impressed by the quality and can't stop recommending it. It's also a lot of fun!

name

Francisco Aguilar Meléndez

Data Scientist

+11

Company

About Careers Leadership Talent Science Newsroom

Collections

Generative AI Business & Leadership Interview Prep AI & Machine Learning Learn to Code Data Science & Engineering

Platform

Platform Overview Skills Assessments Live Tech Interviews AI Interviewer AI Role-Play AI Tutoring with Cosmo

Roles

Talent Acquisition Engineering Leaders Sales Leaders CS & Support Leaders IO Psychologists Individuals

Resources

Resource Library Blog Customer Stories Interview Prep API Docs

Support

Copyright © 2026 CodeSignal

Privacy Terms Compliance & Trust