When using delegateExpressions, you can use all beans that ere defined in your engine. Concrete:
- All beans listed in the property "beans" of the processEngineConfiguration, when using non-spring processEngineConfigurtion
- All spring-beans in your application-context, when using SpringProcessEngineCOnfiguration when beans-property is not configured
- All referenced spring-beans in the "beans" property, when using Spring ProcessEngineConfiguration.
About testing. When using spring, you can define (or include) a test-context that mocks your classes or replaces them with dummies you can use and assert later.
This is a bit trickier when not in spring-context. But just setting serializable java beans as process-variable will be able to reslove this. All serializable's touched (so eg. when your dummy delegate changes a member field), the bean will be saved to the DB agian. This mean that you can also assert stuff in your test afterwards, by inspecting the process-variables.