The developer preview for Windows Phone 8.1 is now available for developers to start building and testing applications alongside the tooling delivered in Visual Studio 2013 Update 2 RC.
The Windows Phone Preview for Developers program is working in line with the Windows Phone Store, which is now starting to accept app submissions and to enable app linking.
To update a device from Windows Phone 8 to 8.1 developers will need to download the developer preview app and opt into the program (the process is outlined on the Windows Phone Dev Center). If a phone is already opted in, then developers can simply check settings and check for an update.
"The Windows Phone Preview program, introduced last October, gives our developer community access to pre-release builds of Windows Phone updates before the operating system updates are made generally available to consumers. We make these updates available to you to enable on-device testing, and to enable you to build and test platform capabilities not present in the emulator," said Microsoft.
The firm says that it realizes how critical it is for programmers to see an app running on a physical phone prior to submitting to the store. Microsoft also notes that most emulator-based testing typically is focused on functional testing (does the code work as designed), while on-phone testing tells more about the app's real-world usability (e.g., touch target sizing, load times).
Going further than any kind of testing, there are a number of application usage scenarios that simply cannot be performed using the emulator alone, such as those involving device sensors like Bluetooth, NFC, and the camera.