This project investigates agents testing, and in particular how to apply Behaviour Driven Development in MAS acceptance and system testing. The proposed approach is simple, modular, and hace to permit the stakeholders to describe the requested application behaviour. Our approach is integrated into a testing framework, called BEAST-Tool (BEhavioural Agent Simple Testing Tool), which can generate the skeleton of test cases and run them, given the specification of the stakeholders in plain text, following the structure given/when/then. Our tool allows the automatic test generation with JADEX and JADE platforms, and can easily adapted to include other agent platforms. Its developed to realize the acceptance and system tests on the desired software. Besides, mock agents are integrated to interact with the agents under test to permit the unit agent and integration tests.