The reduction to absurdity is tests that essentially parse the code they're testing and assert the AST. Any unit test should really be from the point of view o

The reduction to absurdity is tests that essentially parse the code they're testing and assert the AST. Any unit test should really be from the point of view of checking what the code does, as opposed to checking what code was written. Structural tests by definition don't check what the code does - they're way to parse the code and check the AST is structured a certain way.