# To the Attention of Mobile Software Developers: Guess What, Test your App!

## TL;DR

This study reveals that mobile app testing is often ad hoc, yet crucial for quality and community engagement, with limited use of automated testing and CI/CD pipelines in mobile development.

## Contribution

It provides an extensive analysis of testing practices in mobile app development, highlighting gaps and proposing directions for improving testing and automation.

## Key findings

- Mobile apps are tested in an ad hoc manner or not at all.
- Testing correlates with higher user ratings and fewer code issues.
- Only 26% of mobile apps use CI/CD pipelines, partly due to lack of automated testing.

## Abstract

Software testing is an important phase in the software development life-cycle because it helps in identifying bugs in a software system before it is shipped into the hand of its end users. There are numerous studies on how developers test general-purpose software applications. The idiosyncrasies of mobile software applications, however, set mobile apps apart from general-purpose systems (e.g., desktop, stand-alone applications, web services). This paper investigates working habits and challenges of mobile software developers with respect to testing. A key finding of our exhaustive study, using 1000 Android apps, demonstrates that mobile apps are still tested in a very ad hoc way, if tested at all. However, we show that, as in other types of software, testing increases the quality of apps (demonstrated in user ratings and number of code issues). Furthermore, we find evidence that tests are essential when it comes to engaging the community to contribute to mobile open source software. We discuss reasons and potential directions to address our findings. Yet another relevant finding of our study is that Continuous Integration and Continuous Deployment (CI/CD) pipelines are rare in the mobile apps world (only 26% of the apps are developed in projects employing CI/CD) --- we argue that one of the main reasons is due to the lack of exhaustive and automatic testing.