GebはGroovyを使って実装されたBrowserの自動実行ツール。内部的にはSelniumを利用しているらしい。
Geb is a developer focused tool for automating the interaction between web browsers and web content. It uses the dynamic language features of Groovy to provide a powerful content definition DSL (for modelling content for reuse) and key concepts from jQuery to provide a powerful content inspection and traversal API (for finding and interacting with content).