A new version of the Bun JavaScript runtime and toolkit is out with enhanced testing support and improved memory management. The latter is a critical issue to devs and follows complaints of memory leaks causing problems in production. Bun, acquired by Anthropic in December 2025, is both a bundler for compiling TypeScript or JavaScript applications for the browser, and a runtime for server-side code. It competes with the long-established Node.js, latest version 25.9, and Deno, developed by Node.js creator Ryan Dahl.  New features in 1.1.13 include improvements to the test runner, which is intended to be compatible with the popular Jest testing framework. This version introduces an isolate flag, which runs each test in a fresh environment, and a parallel flag, which runs concurrent tests across a user-defined number of processes. It is also now possible to split tests across multiple test runners with the shard flag, matching Jest's syntax.…