How Bolt optimized their CI pipeline to reduce their test run time by over 3x

Bolt has optimized its testing process by improving the efficiency of both unit and integration tests within its continuous integration (CI) pipeline using CircleCI. Unit tests, which run against every pull request and commit, were made faster by parallelizing the test execution and reducing dependency download times through caching, cutting the workflow time from 15 to 5 minutes. For integration tests, Bolt adopted a strategy that allows for easier reruns by segmenting tests into smaller jobs, thus preventing the need to rerun entire test suites when only a few tests fail. These tests, which are executed across different environments using both local headless browsers and remote services like Browserstack, were further streamlined using CircleCI's new v2 API to manage workflows more effectively. This reorganization reduced the overall test time and complexity, making the system more comprehensible and manageable, especially for new engineers.