simulate api for debug trace call

main/src/main.rs

@@ -4,7 +4,8 @@
 use alloy_primitives::TxHash;
 use clap::{ArgGroup, Args, CommandFactory, Parser, Subcommand};
 use constants::DEFAULT_ENDPOINT;
-use ethers::types::H160;
+use ethers::abi::Bytes;
+use ethers::types::{H160, U256};
 use eyre::{bail, eyre, Context, Result};
 use std::path::PathBuf;
 use std::{fmt, path::Path};
@@ -97,6 +98,9 @@
     /// Trace a transaction.
     #[command(visible_alias = "t")]
     Trace(TraceArgs),
+    /// Simulate a transaction.
+    #[command(visible_alias = "s")]
+    Simulate(SimulateArgs),
 }
 
 #[derive(Args, Clone, Debug)]
@@ -266,6 +270,45 @@
     use_native_tracer: bool,
 }
 
+#[derive(Args, Clone, Debug)]
+pub struct SimulateArgs {
+    /// RPC endpoint.
+    #[arg(short, long, default_value = "http://localhost:8547")]
+    endpoint: String,
+
+    /// From address.
+    #[arg(short, long)]
+    from: Option<H160>,
+
+    /// To address.
+    #[arg(short, long)]
+    to: Option<H160>,
+
+    /// Gas limit.
+    #[arg(long)]
+    gas: Option<u64>,
+
+    /// Gas price.
+    #[arg(long)]
+    gas_price: Option<U256>,
+
+    /// Value to send with the transaction.
+    #[arg(short, long)]
+    value: Option<U256>,
+
+    /// Data to send with the transaction, as a hex string (with or without '0x' prefix).
+    #[arg(short, long)]
+    data: Option<Bytes>,
+
+    /// Project path.
+    #[arg(short, long, default_value = ".")]
+    project: PathBuf,
+
+    /// If set, use the native tracer instead of the JavaScript one.
+    #[arg(short, long, default_value_t = false)]
+    use_native_tracer: bool,
+}
+
 #[derive(Clone, Debug, Args)]
 #[clap(group(ArgGroup::new("key").required(true).args(&["private_key_path", "private_key", "keystore_path"])))]
 struct AuthOpts {
@@ -444,10 +487,10 @@
 // supported. These extensions are now incorporated as part of the `cargo-stylus` command itself and
 // will be the preferred method of running them.
 fn is_deprecated_extension(subcommand: &str) -> bool {
     match subcommand {
         "cargo-stylus-check" | "cargo-stylus-cgen" | "cargo-stylus-replay" => true,
         _ => false,
     }
 }
 
 async fn main_impl(args: Opts) -> Result<()> {
@@ -473,6 +516,9 @@
                 "stylus activate failed"
             );
         }
+        Apis::Simulate(args) => {
+            run!(simulate(args).await, "failed to simulate transaction");
+        }
         Apis::Cgen { input, out_dir } => {
             run!(gen::c_gen(&input, &out_dir), "failed to generate c code");
         }
@@ -557,6 +603,13 @@
     Ok(())
 }
 
+async fn simulate(args: SimulateArgs) -> Result<()> {
+    let provider = sys::new_provider(&args.endpoint)?;
+    let trace = Trace::simulate(provider, &args).await?;
+    println!("{}", trace.json);
+    Ok(())
+}
+
 async fn replay(args: ReplayArgs) -> Result<()> {
     if !args.child {
         let rust_gdb = sys::command_exists("rust-gdb");

main/src/trace.rs

@@ -4,10 +4,14 @@
 #![allow(clippy::redundant_closure_call)]
 
 use crate::util::color::{Color, DebugColor};
+use crate::SimulateArgs;
 use alloy_primitives::{Address, TxHash, B256, U256};
 use ethers::{
     providers::{JsonRpcClient, Middleware, Provider},
-    types::{GethDebugTracerType, GethDebugTracingOptions, GethTrace, Transaction},
+    types::{
+        BlockId, GethDebugTracerType, GethDebugTracingCallOptions, GethDebugTracingOptions,
+        GethTrace, Transaction, TransactionRequest,
+    },
     utils::__serde_json::{from_value, Value},
 };
 use eyre::{bail, OptionExt, Result, WrapErr};
@@ -77,6 +81,91 @@ impl Trace {
             frame: self.top_frame,
         }
     }
+    pub async fn simulate<T: JsonRpcClient>(
+        provider: Provider<T>,
+        args: &SimulateArgs,
+    ) -> Result<Self> {
+        // Build the transaction request
+        let mut tx_request = TransactionRequest::new();
+
+        if let Some(from) = args.from {
+            tx_request = tx_request.from(from);
+        }
+        if let Some(to) = args.to {
+            tx_request = tx_request.to(to);
+        }
+        if let Some(gas) = args.gas {
+            tx_request = tx_request.gas(gas);
+        }
+        if let Some(gas_price) = args.gas_price {
+            tx_request = tx_request.gas_price(gas_price);
+        }
+        if let Some(value) = args.value {
+            tx_request = tx_request.value(value);
+        }
+        if let Some(data) = &args.data {
+            tx_request = tx_request.data(data.clone());
+        }
+
+        // Use the same tracer as in Trace::new
+        let query = if args.use_native_tracer {
+            "stylusTracer"
+        } else {
+            include_str!("query.js")
+        };
+
+        // Corrected construction of tracer_options
+        let tracer_options = GethDebugTracingCallOptions {
+            tracing_options: GethDebugTracingOptions {
+                tracer: Some(GethDebugTracerType::JsTracer(query.to_owned())),
+                ..Default::default()
+            },
+            ..Default::default()
+        };
+
+        // Use the latest block; alternatively, this can be made configurable
+        let block_id = None::<BlockId>;
+
+        let GethTrace::Unknown(json) = provider
+            .debug_trace_call(tx_request, block_id, tracer_options)
+            .await?
+        else {
+            bail!("Malformed tracing result");
+        };
+
+        if let Value::Array(arr) = json.clone() {
+            if arr.is_empty() {
+                bail!("No trace frames found.");
+            }
+        }
+        // Since this is a simulated transaction, we create a dummy Transaction object
+        let tx = Transaction {
+            from: args.from.unwrap_or_default(),
+            to: args.to,
+            gas: args
+                .gas
+                .map(|gas| {
+                    let bytes = [0u8; 32]; // U256 in both libraries is 32 bytes
+                    gas.to_be_bytes().copy_from_slice(&bytes[..8]); // Convert alloy_primitives::U256 to bytes
+                    ethers::types::U256::from_big_endian(&bytes) // Convert bytes to ethers::types::U256
+                })
+                .unwrap_or_else(ethers::types::U256::zero), // Default to 0 if no gas is provided
+            gas_price: args.gas_price,
+            value: args.value.unwrap_or_else(ethers::types::U256::zero),
+            input: args.data.clone().unwrap_or_default().into(),
+            // Default values for other fields
+            ..Default::default()
+        };
+
+        // Parse the trace frames
+        let top_frame = TraceFrame::parse_frame(None, json.clone())?;
+
+        Ok(Self {
+            top_frame,
+            tx,
+            json,
+        })
+    }
 }
 
 #[derive(Serialize, Deserialize)]