Ladd argues Test Bench's fixtures prove test code can be generalized, composed, and layered like regular code — e.g. a message-handler fixture invoking a schema-equality fixture to compare events. He sees this as breaking a log-jam in the test-automation world, where after BDD the pioneering had stalled. Because fixtures are open-ended test objects that can build on each other, test frameworks can enable a new frontier of higher-level test abstractions — something compilers and static type systems cannot match, since you cannot build new 'types' that the compiler sees on top of other types.