Xamarin -- the company enabling developers to use Microsoft's C# and Visual Studio to write native mobile apps for iOS and Android -- is expanding into the testing realm.

On April 16, Xamarin announced it had purchased LessPainful, the Danish creator of the Calabash cross-platform mobile test-automation framework. Financial terms of the deal were not disclosed. Xamarin plans to keep the LessPainful office in Denmark and plans to hire additional employees there, officials said.

Xamarin also announced today, on the opening day of the company's Evolve 2013 conference (sponsored by Microsoft, among others), that it is opening up its beta of the Xamarin Test Cloud, which is based on Calabash.

Calabash was originally a proprietary library for Android. In January 2012, LessPainful decided to open source Calabash.

The Xamarin Test Cloud is an automated user-interface testing service that is designed to enable mobile developers to test their apps on hundreds of mobile devices. Xamarin's pitch is this kind of service will help developers overcome device silos, letting them test apps on real, non-jailbroken mobile devices.

The Test Cloud is available to developers writing apps using Xamarin's tools, as well as Objective-C, Java, RubyMotion and PhoneGap, Xamarin officials said.

Xamarin has been allowing a select set of testers access the Test Cloud already; today marks the opening of the beta to others interested in kicking the tires. To sign up for the beta, developers can go to the Xamarin Test Cloud page.

General availability of Test Cloud is slated for the third quarter of calendar 2013.

"We asked hundreds of developers which tools they were using for automated UI testing, and only eight percent were doing it at all," said Xamarin CEO Nat Friedman.

Friedman said Xamarin execs had tried themselves all kinds of mobile testing tools and found them hard to use, with cumbersome UIs, fragile tests and poor integration with integrated development environments. They realized there was a real need for a solution in this space.

In other mobile news today, Microsoft updated its Outlook.com app for Android devices. The Android version of the app now has an overhauled interface (more similar to the Outlook.com UI for Windows 8), plus other new features, including support for conversation threading, filters for unread and flagged mail, as well as the ability to mark messages as junk. The app is available from the Google Play store.