Google's (NASDAQ:GOOG) Android mobile operating system has the most market share as well as one of the most diverse ecosystems of all mobile platforms: it runs phones, tablets, cameras and even household appliances. The platform is also still fragmented in many ways, with Android version 4.0 and higher only recently overtaking Android 2.3 Gingerbread in terms of adoption among Android users. And while app testing across all platforms is usually seen as critical to growing and maintaining a loyal user base, a small cottage industry is springing up around Android app testing that seems intended to raise the bar for developers who create for the platform. This includes relatively established services like AppThwack and TestDroid, as well as new offerings like TestFlight, which came to Android in a private beta last week. For a full look at how the app testing industry is flourishing on Android, check out this special feature.