Add generate_spy_event_helpers macro

[ericnordelo]

Fixes #1480

This PR is still missing documentation, and we can improve:

• Output for parsing errors (diagnostics)
• Reducing imports requirements (snforge_std::Event vs Event, etc...)
• Removing the dependency on our EventSpyQueue implementation

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.46%. Comparing base (34f3b56) to head (78df7c5).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1481      +/-   ##
==========================================
- Coverage   93.11%   92.46%   -0.65%     
==========================================
  Files          82       82              
  Lines        2251     2230      -21     
==========================================
- Hits         2096     2062      -34     
- Misses        155      168      +13     

Files with missing lines	Coverage Δ
packages/governance/src/governor/governor.cairo	91.30% <ø> (-1.25%)	⬇️

... and 17 files with indirect coverage changes

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[immrsd]

Looking good! Left a suggestion to introduce a helper trait for building expected events

[immrsd]

What do you think about introducing a helper trait for building expected events?

#[generate_trait]
pub impl ExpectedEventImpl of ExpectedEvent {
    fn new() -> Event {
        Event { keys: array![], data: array![] }
    }

    fn key<T, +Serde<T>, +Drop<T>>(self: Event, value: T) -> Event {
        let Event { mut keys, data } = self;
        value.serialize(ref keys);
        Event { keys, data }
    }

    fn data<T, +Serde<T>, +Drop<T>>(self: Event, value: T) -> Event {
        let Event { keys, mut data } = self;
        value.serialize(ref data);
        Event { keys, data }
    }
}

The the generated code (and also checks that won't use the macro) will become more concise and just look nicer. For example, the code example in the article will change from this:

let mut keys = array![];
keys.append_serde(selector!("Transfer")); // event selector
keys.append_serde(from);                  // key #1
keys.append_serde(to);                    // key #2

let mut data = array![];
data.append_serde(value);                 // non-key data
let expected = Event { keys, data };

spy.assert_emitted(
    @array![(contract_address, expected)],
);

to this:

let expected = ExpectedEvent::new()
    .key(selector!("Transfer"))
    .key(from)
    .key(to)
    .data(value);
spy.assert_emitted(
    @array![(contract_address, expected)]
);

[ericnordelo]

Looks very helpful indeed

[ericnordelo]

Note that we need to merge this PR first, I'm going to add that trait there and refactor the existing tests to use it.