At Sauce Labs, the company writes a large number of Selenium tests for their website and other customers' applications, which are run after every chunk of commits to ensure good test coverage. The build process is critical as it can interfere with developers' workflows if it breaks, so when flaky tests occur, it's a big deal. Flakes happen when tests fail non-deterministically, making it hard to diagnose the issue without running many instances of the test. To tackle this problem, Sauce Labs used Sauce Breakpoints, a feature that allows them to run multiple instances of a test in parallel and catch bugs in their natural habitat. They created 14 versions of a single test, ran all of them in parallel using a custom Nose test runner, and then used programmatic Sauce Breakpoints to enter Breakpoint mode on the failing tests. This allowed them to observe the bug, get into the debug tools, and eventually squash the issue by upgrading their backend code to make session saves synchronous. The use of Sauce Breakpoints enabled them to diagnose and fix a previously elusive flake in just one parallel test run.