Isolating Dependencies with Test Doubles with TypeScript & Jest | CodeSignal Learn

Skip to main content

Software Engineering

305 learners

Isolating Dependencies with Test Doubles with TypeScript & Jest

Discover the pivotal role of test doubles in modern software testing. This introductory session 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.

Jest

TypeScript

5 lessons

25 practices

Less than 4 hours

Programming, Algorithms, and Data Structures

Course details

Isolating Dependencies with Test Doubles: Dummies

Testing Email Parameters with Dummies

Enhancing the Logger Interface

Fix the Test Suite Bug

Implementing Dummies in Test Suites

Master Dummies in Test Suites

Previous Course Next Course: Refactoring by Leveraging Your Tests with TypeScript & Jest

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

Scan to download

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