* Add a `at_least_one!` macro for testing
Similar to the `vec!` macro, but doesn't allow creating an empty list.
* Test if `has_inputs_and_outputs` considers actions
Create a dummy transaction with no inputs and no outputs, and add a
dummy Orchard action to it. The `check::has_inputs_and_outputs`
should succeed, because the consensus rule considers having Orchard
actions as having inputs and/or outputs.
* Refactor to create helper function
Move the code to create a fake Orchard shielded data instance to a
helper function in `zebra_chain::transaction::arbitrary`, so that other
tests can also use it.
* Test coinbase V5 transaction with enable spends
A V5 coinbase transaction that has Orchard shielded data MUST NOT have
the enable spends flag set.
* Test if coinbase without enable spends is valid
A coinbase transaction with Orchard shielded data and without the enable
spends flag set should be valid.
* Add a security comment about the `at_least_one!` macro
This macro must not be used outside tests, because it allows memory denial
of service.
Co-authored-by: teor <teor@riseup.net>
2e0318878a