assert_cmd::cargo_bin use Cargo.toml from a different directory - testing

Question

So I'm developing a CLI that has commands like so:
sandwich [command]
create <destination> - Creates a Rust library at the specified destination to act as the sandwich.
eat - Used from within a library to eat the sandwich.
and I'm writing tests for it now which work fine until I need to write tests for eat:
use assert_cmd::prelude::*;
use predicates::prelude::*;
// It should create a sandwich then eat it.
#[test]
fn create_sandwich_then_eat_it() -> Result<(), Box<dyn std::error::Error>> {
std::env::set_current_dir("tests").expect("Unable to change to test directory");
// This runs the cli and the create command which in turn runs `cargo new pastrami --lib`.
let mut cmd = Command::cargo_bin("sandwichy")?;
cmd.arg("create").arg("veggie");
cmd.assert().success();
// Now we want to eat the sandwich but we need to go into the sandwich directory because the eat command can only be used from a created sandwich.
std::env::set_current_dir("veggie").expect("Unable to change to sandwich directory");
// We try to eat but get an error because the pastrami has a Cargo.toml which is trying to be used to run the command.
let mut cmd_eat = Command::cargo_bin("sandwichy")?;
cmd_eat.arg("eat");
cmd_eat.assert().success();
Ok(())
}
In the example above I get the following error:
---- create_sandwich_then_eat_it stdout ----
Error: CargoError { cause Some(CargoError { kind: CommandFailed, context: Some("error: failed to parse manifest ...etc
So I looked at the docs and it says that cargo_bin runs the command from the current directory and since I changed to the sandwich directory and that has a Cargo.toml I assume it's trying to run something from there which doesn't exist.
I get that it's not an error on the part of cargo_bin because it's doing what it's supposed to be doing but is there a way of accomplishing what I'm trying to do either with or without it?