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Docker adds shift-left tests in AtomicJar Testcontainers buy

Docker stressed its commitment to maintaining the Testcontainers open source project at a time when shift-left testing has become a mainstream priority for enterprise developers.

Shift-left testing will become part of Docker Inc.'s products for developer productivity with this week's acquisition of AtomicJar, a vendor that offers commercial support for the open source Testcontainers library.

AtomicJar was launched in 2021 by the creators of Testcontainers, an open source project founded in 2015 that creates "throwaway, lightweight instances of databases, message brokers, web browsers, or just about anything that can run in a Docker container," according to an AtomicJar blog post. Using these disposable containers with dependencies defined as code, developers can test apps within the local development environment rather than using separate mockups or external test environments. Docker acquired the privately held company for an undisclosed sum.

AtomicJar and Testcontainers will slot into Docker's product line alongside Docker Scout, which performs security vulnerability scans on code as part of developer workflows, according to a company blog post and FAQ. The company also emphasized that Docker plans to maintain Testcontainers as an open source project and absorb all of AtomicJar's employees into the company. AtomicJar has 20 employees, according to ZoomInfo.

"With its support for Java, .NET, Go, Node.js, and six other programming languages, together with its container-based testing automation, Testcontainers has become the de facto standard test framework for the developer's 'inner loop,'" Docker CEO Scott Johnston wrote in the post. "Testcontainers enables step-function improvements in both the quality and speed of application delivery."

Testcontainers is used by companies including Netflix, Uber, Spotify, DoorDash, Google, GitHub, Capital One, Skyscanner and Wise, according to AtomicJar's post. AtomicJar markets Testcontainers Cloud, which hosts test containers for use in continuous integration pipelines. In August, AtomicJar launched a Testcontainers Desktop companion app, advertised on its website with "No local docker daemon needed!"

The official Docker FAQ states that Docker plans to continue support for Testcontainers Cloud "while we work to develop new and better integration options." Testcontainers Desktop is not specifically mentioned.

Enterprises embraced shift-left testing in 2023

The deal comes at a time when enterprise IT organizations have committed more fully to shift-left testing for applications. Using this practice, tests are written by developers and performed early in the software development process rather than after code is written -- a common tenet of Agile and DevOps methodologies.

This would especially help midsize and smaller companies that don't have staff to deal with the open source version.
Rob StrechayLead analyst, TheCube

In the 2022 "Cloud-Native Application Trends" survey from TechTarget's Enterprise Strategy Group, only 29% of respondents reported doing integrated testing in the CI/CD pipeline, said Paul Nashawaty, an analyst at ESG.

"In 2023, we saw that number jump to 66%," Nashawaty said. "This is a significant jump in importance to our respondents."

The acquisition fits well with Docker's focus since 2019 on developer productivity tools and the developer experience, said Rob Strechay, lead analyst at enterprise tech media company TheCube.

"It's part of a larger testing ecosystem, but widely used [in] open source for devs to do unit testing pre-push," Strechay said. "This would especially help midsize and smaller companies that don't have staff to deal with the open source version. ... I believe ease of use will be where Docker continues to integrate it for scale -- going beyond a single unit test."

That prediction was echoed by Kelsey Hightower, a former distinguished engineer at Google Cloud, in a post about the deal on X, formerly known as Twitter.

"Docker changed how we build, package, and run applications," Hightower wrote. "[Testcontainers] has the same potential for tests, not just unit tests, but integration, and end to end testing."

Despite assurances from Docker and AtomicJar's founders in blog posts this week, Strechay predicted that there could be a potential downside to the deal for open source users as Docker integrates Testcontainers into its commercial products.

"I think they will continue with single, one-off [tests] being fine in open source, but enterprises [will use] the Docker version," he said.

Beth Pariseau, senior news writer at TechTarget Editorial, is an award-winning veteran of IT journalism. She can be reached at [email protected] or on Twitter @PariseauTT.

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