fix: force prevrandao on Moonbeam networks

crates/evm/core/src/utils.rs

@@ -6,7 +6,7 @@ use crate::{
 use alloy_consensus::BlockHeader;
 use alloy_json_abi::{Function, JsonAbi};
 use alloy_network::AnyTxEnvelope;
-use alloy_primitives::{Address, Selector, TxKind, U256};
+use alloy_primitives::{Address, Selector, TxKind, B256, U256};
 use alloy_provider::{network::BlockResponse, Network};
 use alloy_rpc_types::{Transaction, TransactionRequest};
 use foundry_config::NamedChain;
@@ -34,18 +34,25 @@ pub fn apply_chain_and_block_specific_env_changes<N: Network>(
     env: &mut revm::primitives::Env,
     block: &N::BlockResponse,
 ) {
+    use NamedChain::*;
     if let Ok(chain) = NamedChain::try_from(env.cfg.chain_id) {
         let block_number = block.header().number();
 
         match chain {
-            NamedChain::Mainnet => {
+            Mainnet => {
                 // after merge difficulty is supplanted with prevrandao EIP-4399
                 if block_number >= 15_537_351u64 {
                     env.block.difficulty = env.block.prevrandao.unwrap_or_default().into();
                 }
 
                 return;
             }
+            Moonbeam | Moonbase | Moonriver | MoonbeamDev => {
+                if env.block.prevrandao.is_none() {
+                    // <https://github.com/foundry-rs/foundry/issues/4232>
+                    env.block.prevrandao = Some(B256::random());
+                }
+            }
             c if c.is_arbitrum() => {
                 // on arbitrum `block.number` is the L1 block which is included in the
                 // `l1BlockNumber` field

crates/forge/tests/it/repros.rs

@@ -180,6 +180,9 @@ test_repro!(3753);
 // https://github.com/foundry-rs/foundry/issues/3792
 test_repro!(3792);
 
+// https://github.com/foundry-rs/foundry/issues/4232
+test_repro!(4232);
+
 // https://github.com/foundry-rs/foundry/issues/4402
 test_repro!(4402);
 

crates/forge/tests/it/test_helpers.rs

@@ -346,6 +346,7 @@ pub fn rpc_endpoints() -> RpcEndpoints {
         ("arbitrum", RpcEndpoint::Url(next_rpc_endpoint(NamedChain::Arbitrum))),
         ("polygon", RpcEndpoint::Url(next_rpc_endpoint(NamedChain::Polygon))),
         ("avaxTestnet", RpcEndpoint::Url("https://api.avax-test.network/ext/bc/C/rpc".into())),
+        ("moonbeam", RpcEndpoint::Url("https://moonbeam-rpc.publicnode.com".into())),
         ("rpcEnvAlias", RpcEndpoint::Env("${RPC_ENV_ALIAS}".into())),
     ])
 }

testdata/default/repros/Issue4232.t.sol

@@ -0,0 +1,31 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+pragma solidity ^0.8.18;
+
+import "ds-test/test.sol";
+import "cheats/Vm.sol";
+
+// https://github.com/foundry-rs/foundry/issues/4232
+contract Issue4232Test is DSTest {
+    Vm constant vm = Vm(HEVM_ADDRESS);
+
+    function testFork() public {
+        // Smoke test, worked previously as well
+        vm.createSelectFork("sepolia", 7215400);
+        vm.assertFalse(block.prevrandao == 0);
+
+        // Would previously fail with:
+        // [FAIL: backend: failed while inspecting; header validation error: `prevrandao` not set; `prevrandao` not set; ] setUp() (gas: 0)
+        //
+        // Related fix:
+        // Moonbeam | Moonbase | Moonriver | MoonbeamDev => {
+        //     if env.block.prevrandao.is_none() {
+        //         // <https://github.com/foundry-rs/foundry/issues/4232>
+        //         env.block.prevrandao = Some(B256::random());
+        //     }
+        // }
+        //
+        // Note: public RPC node used for `moonbeam` discards state quickly so we need to fork against the latest block
+        vm.createSelectFork("moonbeam");
+        vm.assertFalse(block.prevrandao == 0);
+    }
+}