SOA (Service-Oriented Architecture) presents unique requirements and challenges for testing. Dynamic reconfiguration in SOA software means that testing need to be adaptive to the changes of the service-oriented applications at runtime. This paper presents a ConfigTest approach to enable the online change of test organization, test scheduling, test deployment, test case binding, and service binding. ConfigTest is based on our previous research on the MAST (Multi-Agents-based Service Testing) framework. It extends MAST with a new test broker architecture, configuration management and event-based subscription/notification mechanism. The test broker decouples test case definition from its implementation and usage. It also decouples the testing system from the services under test. With the configuration management, ConfigTest allows the test agents to bind dynamically to each other and build up their collaborations at runtime. The event mechanism enables that a change in one test artifact can be notified to all the others which subscribe their interests to the change event. This paper presents and analyzes the collaboration diagrams of various testing reconfiguration scenarios and illustrates the ConfigTest approach with an example of service-based book ordering system.