foundry-rs#991 Deterministic Fuzzer with RNG Seeding (foundry-rs#1658)

* feat: basic rng seeding * chore: bump u32 to U256 * feat(config): add additional helper macro * feat: finish fuzz seed impl * bump ethers Co-authored-by: Matthias Seitz <[email protected]>
iFrostizz · Nov 9, 2022 · 0b971c7 · 0b971c7
1 parent 0a0bba9
commit 0b971c7
Show file tree

Hide file tree

Showing 4 changed files with 62 additions and 21 deletions.
diff --git a/Cargo.lock b/Cargo.lock
diff --git a/cli/src/cmd/forge/test/mod.rs b/cli/src/cmd/forge/test/mod.rs
@@ -9,7 +9,7 @@ use crate::{
     suggestions, utils,
 };
 use clap::{AppSettings, Parser};
-use ethers::solc::utils::RuntimeOrHandle;
+use ethers::{solc::utils::RuntimeOrHandle, types::U256};
 use forge::{
     decode::decode_console_logs,
     executor::{inspector::CheatsConfig, opts::EvmOpts},
@@ -22,17 +22,22 @@ use forge::{
     MultiContractRunner, MultiContractRunnerBuilder,
 };
 use foundry_common::evm::EvmArgs;
-use foundry_config::{figment::Figment, Config};
+use foundry_config::{figment, figment::Figment, Config};
+use proptest::test_runner::{RngAlgorithm, TestRng};
 use regex::Regex;
 use std::{collections::BTreeMap, path::PathBuf, sync::mpsc::channel, thread, time::Duration};
 use tracing::trace;
 use watchexec::config::{InitConfig, RuntimeConfig};
 use yansi::Paint;
 mod filter;
 pub use filter::Filter;
+use foundry_config::figment::{
+    value::{Dict, Map},
+    Metadata, Profile, Provider,
+};
 
 // Loads project's figment and merges the build cli arguments into it
-foundry_config::impl_figment_convert!(TestArgs, opts, evm_opts);
+foundry_config::merge_impl_figment_convert!(TestArgs, opts, evm_opts);
 
 #[derive(Debug, Clone, Parser)]
 #[clap(global_setting = AppSettings::DeriveDisplayOrder)]
@@ -90,6 +95,9 @@ pub struct TestArgs {
     /// List tests instead of running them
     #[clap(long, short, help_heading = "DISPLAY OPTIONS")]
     list: bool,
+
+    #[clap(long, help = "Set seed used to generate randomness during your fuzz runs",   parse(try_from_str = utils::parse_u256))]
+    pub fuzz_seed: Option<U256>,
 }
 
 impl TestArgs {
@@ -108,12 +116,7 @@ impl TestArgs {
         // merge all configs
         let figment: Figment = self.into();
         let evm_opts = figment.extract()?;
-        let mut config = Config::from_provider(figment).sanitized();
-
-        // merging etherscan api key into Config
-        if let Some(etherscan_api_key) = &self.etherscan_api_key {
-            config.etherscan_api_key = Some(etherscan_api_key.to_string());
-        }
+        let config = Config::from_provider(figment).sanitized();
         Ok((config, evm_opts))
     }
 
@@ -132,6 +135,25 @@ impl TestArgs {
     }
 }
 
+impl Provider for TestArgs {
+    fn metadata(&self) -> Metadata {
+        Metadata::named("Core Build Args Provider")
+    }
+
+    fn data(&self) -> Result<Map<Profile, Dict>, figment::Error> {
+        let mut dict = Dict::default();
+        if let Some(fuzz_seed) = self.fuzz_seed {
+            dict.insert("fuzz_seed".to_string(), fuzz_seed.to_string().into());
+        }
+
+        if let Some(ref etherscan_api_key) = self.etherscan_api_key {
+            dict.insert("etherscan_api_key".to_string(), etherscan_api_key.to_string().into());
+        }
+
+        Ok(Map::from([(Config::selected_profile(), dict)]))
+    }
+}
+
 impl Cmd for TestArgs {
     type Output = TestOutcome;
 
@@ -286,7 +308,16 @@ pub fn custom_run(args: TestArgs, include_fuzz_tests: bool) -> eyre::Result<Test
         max_global_rejects: config.fuzz_max_global_rejects,
         ..Default::default()
     };
-    let fuzzer = proptest::test_runner::TestRunner::new(cfg);
+
+    let fuzzer = if let Some(ref fuzz_seed) = config.fuzz_seed {
+        let mut bytes: [u8; 32] = [0; 32];
+        fuzz_seed.to_big_endian(&mut bytes);
+        let rng = TestRng::from_seed(RngAlgorithm::ChaCha, &bytes);
+        proptest::test_runner::TestRunner::new_with_rng(cfg, rng)
+    } else {
+        proptest::test_runner::TestRunner::new(cfg)
+    };
+
     let mut filter = args.filter(&config);
 
     trace!(target: "forge::test", ?filter, "using filter");

diff --git a/cli/tests/it/config.rs b/cli/tests/it/config.rs
@@ -59,6 +59,7 @@ forgetest!(can_extract_config_values, |prj: TestProject, mut cmd: TestCommand| {
         fuzz_runs: 1000,
         fuzz_max_local_rejects: 2000,
         fuzz_max_global_rejects: 100203,
+        fuzz_seed: Some(1000.into()),
         ffi: true,
         sender: "00a329c0648769A73afAc7F9381D08FB43dBEA72".parse().unwrap(),
         tx_origin: "00a329c0648769A73afAc7F9F81E08FB43dBEA72".parse().unwrap(),

diff --git a/config/src/lib.rs b/config/src/lib.rs
@@ -254,6 +254,11 @@ pub struct Config {
     /// by proptest, to be encountered during usage of `vm.assume`
     /// cheatcode.
     pub fuzz_max_global_rejects: u32,
+    /// Optional seed for the fuzzing RNG algorithm
+    #[serde(
+        deserialize_with = "ethers_core::types::serde_helpers::deserialize_stringified_numeric_opt"
+    )]
+    pub fuzz_seed: Option<U256>,
     /// Print the names of the compiled contracts
     pub names: bool,
     /// Print the sizes of the compiled contracts
@@ -1460,6 +1465,7 @@ impl Default for Config {
             fuzz_runs: 256,
             fuzz_max_local_rejects: 1024,
             fuzz_max_global_rejects: 65536,
+            fuzz_seed: None,
             ffi: false,
             sender: Config::DEFAULT_SENDER,
             tx_origin: Config::DEFAULT_SENDER,
@@ -2850,6 +2856,7 @@ mod tests {
                 fuzz_max_global_rejects = 65536
                 fuzz_max_local_rejects = 1024
                 fuzz_runs = 256
+                fuzz_seed = '0x3e8'
                 gas_limit = 9223372036854775807
                 gas_price = 0
                 gas_reports = ['*']
@@ -2887,6 +2894,8 @@ mod tests {
             )?;
 
             let config = Config::load_with_root(jail.directory());
+
+            assert_eq!(config.fuzz_seed, Some(1000.into()));
             assert_eq!(
                 config.remappings,
                 vec![Remapping::from_str("nested/=lib/nested/").unwrap().into()]