When step functions return Result values it is common to assert on their
outcome. The rstest-bdd crate exports two helper macros to streamline these
checks:
use rstest_bdd::{assert_step_err, assert_step_ok};
let ok: Result<(), &str> = Ok(());
assert_step_ok!(ok);
let err: Result<(), &str> = Err("boom");
let e = assert_step_err!(err, "boom");
assert_eq!(e, "boom");
assert_step_ok! unwraps an Ok value and panics with the error message when
the result is Err. assert_step_err! unwraps the error and optionally checks
that its display contains a substring. Both macros return their unwrapped
values, allowing further inspection when required.