Uber Migrates 75,000+ Test Classes from Junit 4 to Junit 5 Using Automated Code Transformation

Leela Kumili — Mon, 27 Apr 2026 14:07:00 GMT

Uber engineers migrated over 75,000 test classes from JUnit 4 to JUnit 5 using automated code transformation with OpenRewrite and internal orchestration. By enabling the JUnit Platform for dual execution with Bazel and validating changes through CI, the team modernized testing infrastructure while maintaining correctness at monorepo scale.

By Leela Kumili

Dropbox Collaborates with GitHub to Reduce Monorepo Size from 87GB to 20GB

Leela Kumili — Wed, 22 Apr 2026 14:14:00 GMT

Dropbox reduced its backend monorepo from 87GB to 20GB by optimizing Git delta compression in collaboration with GitHub. The changes improved clone times, CI performance, and developer velocity, highlighting how repository storage inefficiencies can impact large-scale engineering workflows.

By Leela Kumili

InfoQ - Productivity - News

Uber Migrates 75,000+ Test Classes from Junit 4 to Junit 5 Using Automated Code Transformation

Dropbox Collaborates with GitHub to Reduce Monorepo Size from 87GB to 20GB