assert_noop! doesn't pass the test - substrate

Question

This is my test:
assert_noop!(
TemplateModule::commit_vote(
Origin::signed(5),
count - 1,
0,
"2-Votinghash".as_bytes().to_vec()
),
Error::<Test>::AlreadyCommitUsed
);
When I add another error its fails as:
thread 'tests::commit_vote' panicked at 'assertion failed: `(left == right)`
left: `Err(DispatchError::Module { index: 1, error: 7, message: Some("AlreadyCommitUsed") })`,
right: `Err(DispatchError::Module { index: 1, error: 4, message: Some("DepartmentNotAssociated") })`', pallets/template/src/tests.rs:106:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Where as when I add AlreadyCommitUsed as error, it gives following strange inequality:
thread 'tests::commit_vote' panicked at 'assertion failed: `(left == right)`
left: `[218, 23, 247, 200, 228, 182, 117, 227, 150, 32, 248, 47, 209, 182, 207, 246, 198, 19, 20, 74, 185, 125, 35, 94, 74, 161, 128, 199, 114, 155, 238, 228]`,
right: `[128, 69, 23, 167, 50, 250, 133, 59, 10, 41, 100, 95, 141, 187, 236, 154, 67, 174, 251, 17, 219, 45, 146, 141, 204, 77, 245, 38, 95, 131, 122, 48]`', pallets/template/src/tests.rs:106:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
This is my commit_vote function:
#[weight = 10_000 + T::DbWeight::get().reads_writes(3,3)]
pub fn commit_vote(origin, departmentid:u128, voting_cycle:u128, vote_commit:Vec<u8>) -> dispatch::DispatchResult {
let who = ensure_signed(origin.clone())?;
Self::check_citizen_associated_department(who.clone(), departmentid)?;
let status = VoteStatus::get((departmentid, voting_cycle, vote_commit.clone()));
match status {
Some(value) => {
if value == true {
Err(Error::<T>::AlreadyCommitUsed.into())
} else {
Err(Error::<T>::VoteRevealed.into())
}
}
None => {
Self::add_vote(departmentid, voting_cycle, vote_commit)?;
Ok(())
}
}
}
This is my helper function:
// Helper functions
impl<T: Config> Module<T> {
fn check_citizen_associated_department(
who: T::AccountId,
departmentid: u128,
) -> dispatch::DispatchResult {
let approved_peer_dep = PeerDepartments::<T>::get(&who);
match approved_peer_dep.binary_search(&departmentid) {
Ok(_) => {
Self::deposit_event(RawEvent::PeerDepartment(departmentid, who));
Ok(())
}
Err(_) => Err(Error::<T>::DepartmentNotAssociated.into()),
}
}
}
Yes, the error is because of the helper function, the error disappers when deposit_event of check_citizen_associated_department is removed. Not sure if its right way to write helper function.

Answer 1

This error:
thread 'tests::commit_vote' panicked at 'assertion failed: `(left == right)`
left: `[218, 23, 247, 200, 228, 182, 117, 227, 150, 32, 248, 47, 209, 182, 207, 246, 198, 19, 20, 74, 185, 125, 35, 94, 74, 161, 128, 199, 114, 155, 238, 228]`,
right: `[128, 69, 23, 167, 50, 250, 133, 59, 10, 41, 100, 95, 141, 187, 236, 154, 67, 174, 251, 17, 219, 45, 146, 141, 204, 77, 245, 38, 95, 131, 122, 48]`', pallets/template/src/tests.rs:106:5
note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace
Is telling you that your extrinsic resulted in an error, but you also changed the state of the runtime. This is against the rules of how you can use Substrate.
This is the purpose of the assert_noop! macro:
https://crates.parity.io/frame_support/macro.assert_noop.html
There is a policy that all extrinsics must be "Check First, Write Last", as in, by the time you actually go about modifying the runtime state, there should be no way for an error to occur.
The problem seems to be that you emit an event in check_citizen_associated_department, which modifies the state, but then can error in match status.
You will need to fix your logic such that an event is only emitted when you know everything else will succeed.