A Qualitative Study on the Sources, Impacts, and Mitigation Strategies of Flaky Tests

TL;DR

This study explores the sources, impacts, and mitigation strategies of flaky tests through interviews with practitioners, revealing that flakiness arises from multiple factors and can be mitigated by guidelines and stable infrastructure.

Contribution

It provides qualitative insights into the causes and mitigation of flaky tests, highlighting the importance of infrastructure stability and guidelines in practice.

Findings

Flakiness originates from tests, code, system interactions, infrastructure, and external factors.

Mitigation involves guidelines and stable infrastructure.

Flakiness impacts testing practices and product quality.

Abstract

Test flakiness forms a major testing concern. Flaky tests manifest non-deterministic outcomes that cripple continuous integration and lead developers to investigate false alerts. Industrial reports indicate that on a large scale, the accrual of flaky tests breaks the trust in test suites and entails significant computational cost. To alleviate this, practitioners are constrained to identify flaky tests and investigate their impact. To shed light on such mitigation mechanisms, we interview 14 practitioners with the aim to identify (i) the sources of flakiness within the testing ecosystem, (ii) the impacts of flakiness, (iii) the measures adopted by practitioners when addressing flakiness, and (iv) the automation opportunities for these measures. Our analysis shows that, besides the tests and code, flakiness stems from interactions between the system components, the testing infrastructure, and external factors. We also highlight the impact of flakiness on testing practices and product quality and show that the adoption of guidelines together with a stable infrastructure are key measures in mitigating the problem.