Experience: developing a usable battery drain testing and diagnostic tool for the mobile industry

In this paper, we report on our 6-year experience developing Eagle Tester (eTester for short) - a mobile battery drain testing and diagnostic tool. We show how eTester evolved from an "academic" prototype to a fully automated tool usable by the mobile industry. We first present the design of our initial research prototype and discuss 8 key requirements for a usable battery drain testing and diagnostic tool gathered from some of the most popular software vendors in the Android ecosystem. These requirements posed interesting scientific and engineering challenges such as how to accurately estimate battery drain without requiring a priori power modeling, work on unmodified devices, and automatically monitor code evolution to generate high-fidelity battery spike alerts with actionable insights. These requirements motivated a complete overhaul of the eTester design and led to the creation of a novel battery drain testing methodology. We show how the redesigned eTester was used to effortlessly find battery bugs in some of the most popular Android apps with hundreds of millions of users, such as Netflix and CNN. We are open-sourcing eTester to encourage further research in battery diagnosis and to empower developers to write battery-efficient mobile software.