Root causing flaky tests in a large-scale industrial setting

Abstract

In today’s agile world, developers often rely on continuous integration pipelines to help build and validate their changes by executing tests in an efficient manner. One of the significant factors that hinder developers’ productivity is flaky tests—tests that may pass and fail with the same version of code. Since flaky test failures are not deterministically reproducible, developers often have to spend hours only to discover that the occasional failures have nothing to do with their changes. However, ignoring failures of flaky tests can be dangerous, since those failures may represent real faults in the production code. Furthermore, identifying the root cause of flakiness is tedious and cumbersome, since they are often a consequence of unexpected and non-deterministic behavior due to various factors, such as concurrency and external dependencies.