RunnerScheduler Represents a strategy for scheduling when individual test methods should be run (in serial or parallel) WARNING: still experimental, may go away. 


FrameworkField Represents a field on a test class (currently used only for Rules in BlockJUnit4ClassRunner, but custom runners can make other uses)  
FrameworkMethod Represents a method on a test class to be invoked at the appropriate point in test execution. 
RunnerBuilder A RunnerBuilder is a strategy for constructing runners for classes. 
Statement Represents one or more actions to be taken at runtime in the course of running a JUnit test suite. 
TestClass Wraps a class to be run, providing method validation and annotation searching  


InitializationError Represents one or more problems encountered while initializing a Runner