Collectd is responsible for gathering and storing data from various sources, including SNMP, JMX, HTTP and NSClient.
collectd has not been refactored or instrumented for testing as of May 12, 2005. As part of the efforts on the threshd setting up for testing, the RrdStrategies are being made testable. There are also efforts being made towards creating Mock SNMP agents that could be used for testing. Matt has suggested looking at jMock for other ways of implementing tests for difficult pieces to simulate.