AtomicJar, nuclear integration testing just got jammy

AtomicJar is a startup on a mission to make integration testing easier for developers across the software development lifecycle.

The organisation aims to serve the Testcontainers community, build new enterprise features and functionality and to continue to extend the ecosystem of frameworks in the Java ecosystem that provide native integration testing with Testcontainers.

Testcontainers is a Java library that supports JUnit tests, providing lightweight, throwaway instances of common databases, Selenium web browsers, or anything else that can run in a Docker container — JUnit itself is JUnit is a unit testing framework for the Java programming language that falls into the SUnit family of unit testing frameworks.

AtomicJar’s founding team includes Richard North, creator of, Testcontainers and Sergei Egorov, who is co-maintainer of Testcontainers, a Java Champion and an Apache Software Foundation committer.

North created Testcontainers in 2015 while a chief engineer at Deloitte Digital. He observed that integration testing’s hopelessly complicated set-up — i.e. everything from creating consistent local setups, to configuring databases and countless other issues — was a constant source of thrashing, hashing and bashing for developer teams that needed a reliable way to test their code against real production-like dependencies.

North built Testcontainers as an open source library that lets developers, directly from their test code, “test with containers” against everything from data stores and databases (e.g. Redis, PostgreSQL), to anything else that can run in a Docker container (Kafka, RabbitMQ, Selenium, etc.).

Within the year after its launch, Testcontainers had surpassed a number of other existing integration testing projects, to become the most popular Docker-based integration testing library.

“Unit testing is fine, but without a proper integration testing, especially if you work with external resources like databases and other services, you might not know how your application will behave once it has been deployed to the real environment,” said Egorov, AtomicJar co-founder and CEO. “We want to give developers a set of tools that will leave no excuses to not do integration testing. With AtomicJar, we will ensure that literally anyone in the world can use these tools.”

According to Oracle’s Developers Blog, Testcontainers makes data access layer integration tests easier, developers can use a containerised instance of a MySQL, PostgreSQL or Oracle database to test data access layer code for complete compatibility, but without requiring complex setup on developers’ machines.

This means that programmers can be safe in the knowledge that tests will always start with a known DB state.

“For too long, people have treated integration testing like a dirty word, even when it’s critically important. It’s been too hard to do, and too hard to get right,” said North, Testcontainers creator and AtomicJar CTO. “We’re here to make testing so attractive that devs will want to do it, rather than fear it.”

AtomicJar is opening a private beta for a limited number of enterprises to try the enhancements and extensions the company has added to Testcontainers with the waiting list linked here.