A new edition of Rhomobile’s Rhodes framework for cross-platform smartphone development is designed to facilitate agile methods, the company has announced.

Rhodes is an open-source framework for writing Ruby applications that run natively on Android, BlackBerry, iPhone, Symbian and Windows Mobile devices. It includes binaries that abstract away each underlying platform, and developers use a single API for accessing native resources, said CEO Adam Blum.

Rhodes 1.4 features built-in tools for test-driven development, and it allows developers to write executable specifications that test applications, said Blum. The update was released earlier this week.

Further, Rhodes lets people write interfaces in HTML, which allows for rapid iteration, he added.

“[Test-driven development] is part of the general theme of taking agile development methods that are mostly applied to only Web development, and taking all of that goodness, productivity and nimbleness to building smartphone apps,” Blum explained.

A newly introduced interactive debugger gives developers the ability to step through Ruby code on devices. At present, it only works for Android and iPhone emulators from the respective SDKs, Blum noted.

The upgrade also adds an integrated debugger for Mac OS X, database-based event logging, and support for BlackBerry Java Development Environment v5.0. Future editions will add support for MeeGo and Palm’s Web OS, Blum said.

Ruby is a modern and productive language that enables Web developers to leverage their skills to write applications in a modern Model-View-Controller architecture, Blum said. “They don’t need to use a 30-year-old language like Objective C,” he added.