boilerplate in the rendering stage. Just render
and test (missing the parse stage).

`fixture` and moved the parsing code in
`extend_with_function_attrs` trait impl

that're already tested in future module

the old impl. Also recoverd tests for
errors but implemented them in future
module

logic

Missed the global one

pass arguments info down to the
renderers and impleneted all tests
in render code to check that the
parsed info will used correctly.

method because we want the future in the
signature. Now E2E tests for fixture are
enabled and work.