fix: ensure prevrandao is set on reset fork

crates/anvil/src/eth/backend/mem/mod.rs

@@ -398,11 +398,12 @@ impl Backend {
                     timestamp: fork_block.timestamp.to_alloy(),
                     gas_limit: fork_block.gas_limit.to_alloy(),
                     difficulty: fork_block.difficulty.to_alloy(),
-                    prevrandao: fork_block.mix_hash.map(|h| h.to_alloy()),
+                    // ensures prevrandao is set
+                    prevrandao: Some(fork_block.mix_hash.map(|h| h.to_alloy()).unwrap_or_default()),
                     // Keep previous `coinbase` and `basefee` value
                     coinbase: env.block.coinbase,
                     basefee: env.block.basefee,
-                    ..Default::default()
+                    ..env.block.clone()
                 };
 
                 self.time.reset((env.block.timestamp.to_ethers()).as_u64());

crates/anvil/tests/it/fork.rs

@@ -899,3 +899,35 @@ async fn can_override_fork_chain_id() {
     let chain_id = provider.get_chainid().await.unwrap();
     assert_eq!(chain_id.as_u64(), chain_id_override);
 }
+
+// <https://github.com/foundry-rs/foundry/issues/6485>
+#[tokio::test(flavor = "multi_thread")]
+async fn test_fork_reset_moonbeam() {
+    crate::init_tracing();
+    let (api, handle) = spawn(
+        fork_config()
+            .with_eth_rpc_url(Some("https://rpc.api.moonbeam.network".to_string()))
+            .with_fork_block_number(None::<u64>),
+    )
+    .await;
+    let provider = handle.http_provider();
+
+    let accounts: Vec<_> = handle.dev_wallets().collect();
+    let from = accounts[0].address();
+
+    let tx = TransactionRequest::new().to(Address::random()).value(1337u64).from(from);
+    let tx = provider.send_transaction(tx, None).await.unwrap().await.unwrap().unwrap();
+    assert_eq!(tx.status, Some(1u64.into()));
+
+    // reset to check timestamp works after resetting
+    api.anvil_reset(Some(Forking {
+        json_rpc_url: Some("https://rpc.api.moonbeam.network".to_string()),
+        block_number: None,
+    }))
+    .await
+    .unwrap();
+
+    let tx = TransactionRequest::new().to(Address::random()).value(1337u64).from(from);
+    let tx = provider.send_transaction(tx, None).await.unwrap().await.unwrap().unwrap();
+    assert_eq!(tx.status, Some(1u64.into()));
+}