Have the coins pallet emit events via serai_core_pallet

`serai_core_pallet` solely defines an accumulator for the events. We use the
traditional `frame_system::Events` to store them for now and enable retrieval.

substrate/coins/src/mock.rs

@@ -1,8 +1,8 @@
 //! Test environment for Coins pallet.
 
-use sp_runtime::BuildStorage;
+use borsh::BorshDeserialize;
 
-use frame_support::{derive_impl, construct_runtime};
+use frame_support::{sp_runtime::BuildStorage, derive_impl, construct_runtime};
 
 use crate::{self as coins, CoinsInstance};
 
@@ -10,6 +10,7 @@ construct_runtime!(
   pub enum Test
   {
     System: frame_system,
+    Core: serai_core_pallet,
     Coins: coins::<CoinsInstance>,
   }
 );
@@ -17,15 +18,28 @@ construct_runtime!(
 #[derive_impl(frame_system::config_preludes::TestDefaultConfig)]
 impl frame_system::Config for Test {
   type AccountId = sp_core::sr25519::Public;
-  type Lookup = sp_runtime::traits::IdentityLookup<Self::AccountId>;
+  type Lookup = frame_support::sp_runtime::traits::IdentityLookup<Self::AccountId>;
   type Block = frame_system::mocking::MockBlock<Test>;
 }
 
+impl serai_core_pallet::Config for Test {}
+
 impl crate::Config<CoinsInstance> for Test {
-  type RuntimeEvent = RuntimeEvent;
   type AllowMint = crate::AlwaysAllowMint;
 }
 
+impl TryFrom<RuntimeEvent> for serai_abi::Event {
+  type Error = ();
+  fn try_from(event: RuntimeEvent) -> Result<serai_abi::Event, ()> {
+    match event {
+      RuntimeEvent::Core(serai_core_pallet::Event::Event(event)) => {
+        Ok(serai_abi::Event::deserialize_reader(&mut event.as_slice()).unwrap())
+      }
+      _ => Err(()),
+    }
+  }
+}
+
 pub(crate) fn new_test_ext() -> sp_io::TestExternalities {
   let mut storage = frame_system::GenesisConfig::<Test>::default().build_storage().unwrap();