feat(blockifier): add emit_event cairo native syscall (#1550)

crates/blockifier/src/execution/native/syscall_handler.rs

@@ -25,7 +25,7 @@ use starknet_api::core::{
 };
 use starknet_api::state::StorageKey;
 use starknet_api::transaction::fields::{Calldata, ContractAddressSalt};
-use starknet_api::transaction::L2ToL1Payload;
+use starknet_api::transaction::{EventContent, EventData, EventKey, L2ToL1Payload};
 use starknet_types_core::felt::Felt;
 
 use crate::execution::call_info::{
@@ -45,6 +45,7 @@ use crate::execution::entry_point::{
 use crate::execution::errors::EntryPointExecutionError;
 use crate::execution::execution_utils::execute_deployment;
 use crate::execution::native::utils::{calculate_resource_bounds, default_tx_v2_info};
+use crate::execution::syscalls::exceeds_event_size_limit;
 use crate::execution::syscalls::hint_processor::{
     SyscallExecutionError,
     INVALID_INPUT_LENGTH_ERROR,
@@ -492,11 +493,29 @@ impl<'state> StarknetSyscallHandler for &mut NativeSyscallHandler<'state> {
 
     fn emit_event(
         &mut self,
-        _keys: &[Felt],
-        _data: &[Felt],
-        _remaining_gas: &mut u128,
+        keys: &[Felt],
+        data: &[Felt],
+        remaining_gas: &mut u128,
     ) -> SyscallResult<()> {
-        todo!("Implement emit_event syscall.");
+        self.pre_execute_syscall(remaining_gas, self.context.gas_costs().emit_event_gas_cost)?;
+
+        let order = self.context.n_emitted_events;
+        let event = EventContent {
+            keys: keys.iter().copied().map(EventKey).collect(),
+            data: EventData(data.to_vec()),
+        };
+
+        exceeds_event_size_limit(
+            self.context.versioned_constants(),
+            self.context.n_emitted_events + 1,
+            &event,
+        )
+        .map_err(|e| self.handle_error(remaining_gas, e.into()))?;
+
+        self.events.push(OrderedEvent { order, event });
+        self.context.n_emitted_events += 1;
+
+        Ok(())
     }
 
     fn send_message_to_l1(

crates/blockifier/src/execution/syscalls/syscall_tests/emit_event.rs

@@ -1,4 +1,5 @@
 use itertools::concat;
+#[cfg(feature = "cairo_native")]
 use pretty_assertions::assert_eq;
 use starknet_api::felt;
 use starknet_api::transaction::fields::Calldata;
@@ -25,11 +26,14 @@ const DATA: [Felt; 3] = [
 ];
 const N_EMITTED_EVENTS: [Felt; 1] = [Felt::from_hex_unchecked("0x1")];
 
+#[cfg_attr(
+  feature = "cairo_native",
+  test_case(FeatureContract::TestContract(CairoVersion::Native), 57430; "Native")
+)]
 #[test_case(FeatureContract::TestContract(CairoVersion::Cairo1), 47330; "VM")]
 fn positive_flow(test_contract: FeatureContract, expected_gas: u64) {
-    // TODO(Ori, 1/2/2024): Write an indicative expect message explaining why the conversion
-    // works.
-    let call_info = emit_events(test_contract, &N_EMITTED_EVENTS, &KEYS, &DATA).unwrap();
+    let call_info = emit_events(test_contract, &N_EMITTED_EVENTS, &KEYS, &DATA)
+        .expect("emit_events failed with valued parameters");
     let event = EventContent {
         keys: KEYS.into_iter().map(EventKey).collect(),
         data: EventData(DATA.to_vec()),
@@ -45,35 +49,53 @@ fn positive_flow(test_contract: FeatureContract, expected_gas: u64) {
     );
 }
 
+#[cfg_attr(
+  feature = "cairo_native",
+  test_case(FeatureContract::TestContract(CairoVersion::Native); "Native")
+)]
 #[test_case(FeatureContract::TestContract(CairoVersion::Cairo1); "VM")]
 fn data_length_exceeds_limit(test_contract: FeatureContract) {
     let versioned_constants = VersionedConstants::create_for_testing();
 
     let max_event_data_length = versioned_constants.tx_event_limits.max_data_length;
     let data_too_long = vec![felt!(2_u16); max_event_data_length + 1];
-    let error = emit_events(test_contract, &N_EMITTED_EVENTS, &KEYS, &data_too_long).unwrap_err();
+
+    let call_result = emit_events(test_contract, &N_EMITTED_EVENTS, &KEYS, &data_too_long);
+
+    let error_message = call_result.unwrap_err().to_string();
+
     let expected_error = EmitEventError::ExceedsMaxDataLength {
         data_length: max_event_data_length + 1,
         max_data_length: max_event_data_length,
     };
-    assert!(error.to_string().contains(&expected_error.to_string()));
+    assert!(error_message.contains(&expected_error.to_string()));
 }
 
+#[cfg_attr(
+  feature = "cairo_native",
+  test_case(FeatureContract::TestContract(CairoVersion::Native); "Native")
+)]
 #[test_case(FeatureContract::TestContract(CairoVersion::Cairo1); "VM")]
 fn keys_length_exceeds_limit(test_contract: FeatureContract) {
     let versioned_constants = VersionedConstants::create_for_testing();
 
     let max_event_keys_length = versioned_constants.tx_event_limits.max_keys_length;
     let keys_too_long = vec![felt!(1_u16); max_event_keys_length + 1];
-    let error = emit_events(test_contract, &N_EMITTED_EVENTS, &keys_too_long, &DATA).unwrap_err();
+
+    let call_result = emit_events(test_contract, &N_EMITTED_EVENTS, &keys_too_long, &DATA);
+
+    let error_message = call_result.unwrap_err().to_string();
+
     let expected_error = EmitEventError::ExceedsMaxKeysLength {
         keys_length: max_event_keys_length + 1,
         max_keys_length: max_event_keys_length,
     };
 
-    assert!(error.to_string().contains(&expected_error.to_string()));
+    assert!(error_message.contains(&expected_error.to_string()));
 }
 
+#[cfg(feature = "cairo_native")]
+#[test_case(FeatureContract::TestContract(CairoVersion::Native); "Native")]
 #[test_case(FeatureContract::TestContract(CairoVersion::Cairo1); "VM")]
 fn event_number_exceeds_limit(test_contract: FeatureContract) {
     let versioned_constants = VersionedConstants::create_for_testing();
@@ -82,12 +104,15 @@ fn event_number_exceeds_limit(test_contract: FeatureContract) {
     let n_emitted_events_too_big = vec![felt!(
         u16::try_from(max_n_emitted_events + 1).expect("Failed to convert usize to u16.")
     )];
-    let error = emit_events(test_contract, &n_emitted_events_too_big, &KEYS, &DATA).unwrap_err();
+    let call_result = emit_events(test_contract, &n_emitted_events_too_big, &KEYS, &DATA);
+
+    let error_message = call_result.unwrap_err().to_string();
+
     let expected_error = EmitEventError::ExceedsMaxNumberOfEmittedEvents {
         n_emitted_events: max_n_emitted_events + 1,
         max_n_emitted_events,
     };
-    assert!(error.to_string().contains(&expected_error.to_string()));
+    assert!(error_message.contains(&expected_error.to_string()));
 }
 
 fn emit_events(