Fix: #138. Set temporary coinbase signer during backtesting if none found

config-backtest-example.toml

@@ -7,6 +7,7 @@ backtest_fetch_eth_rpc_url = "http://127.0.0.1:8545"
 backtest_fetch_eth_rpc_parallel = 400
 backtest_fetch_output_file = "~/.rbuilder/backtest/main.sqlite"
 backtest_fetch_mempool_data_dir = "~/.rbuilder/mempool-data"
+coinbase_secret_key = "env:COINBASE_SECRET_KEY"
 
 sbundle_mergeabe_signers = []
 

crates/rbuilder/src/backtest/backtest_build_block.rs

@@ -7,6 +7,8 @@
 
 use ahash::HashMap;
 use alloy_primitives::utils::format_ether;
+use revm_primitives::hex;
+use secp256k1::{rand::rngs::OsRng, SecretKey};
 
 use crate::backtest::restore_landed_orders::{
     restore_landed_orders, sim_historical_block, ExecutedBlockTx, ExecutedTxs, SimplifiedOrder,
@@ -23,7 +25,7 @@ use crate::{
     utils::timestamp_as_u64,
 };
 use clap::Parser;
-use std::path::PathBuf;
+use std::{env, path::PathBuf};
 
 #[derive(Parser, Debug)]
 struct Cli {
@@ -101,6 +103,10 @@ pub async fn run_backtest_build_block<ConfigType: LiveBuilderConfig>() -> eyre::
         print_onchain_block_data(tx_sim_results, &orders, &block_data);
     }
 
+    if let Err(_) = config.base_config().coinbase_signer() {
+        add_env_coinbase_signer(); 
+    }
+
     let BacktestBlockInput {
         ctx, sim_orders, ..
     } = backtest_prepare_ctx_for_block(
@@ -401,3 +407,17 @@ fn print_onchain_block_data(
         }
     }
 }
+
+// Generate a random private key 
+fn generate_private_key() -> String {
+    let mut rng = OsRng;
+    let secret_key = SecretKey::new(&mut rng); 
+    let hex_secret_key = hex::encode(secret_key.secret_bytes());
+    hex_secret_key
+}
+
+// Add COINBASE_SECRET_KEY as an environment variable during runtime
+fn add_env_coinbase_signer() {
+    let private_key = generate_private_key();
+    env::set_var("COINBASE_SECRET_KEY", private_key);
+}