I'm thinking maybe a list of actions that a test author can register to get advanced logging on before and after states of tests and test blocks, pushing/fetching information from a DB, etc., and generally things that need to live between test setup/teardown and creating the actual test blocks to run.
To make this worth it, we may need to add some helper methods to fetch things like the names of test blocks (in order), any traits associated with the test case, maybe inputs/outputs, etc. As one example, something like:
TestBuilder.RegisterPreTestCaseAction(() => MyHelpers.SaveTestBlocksToDb(TestBuilder.FetchATestBlockMetadata()));