feat(test): add fuzz tests failure persistence

crates/config/src/fuzz.rs

@@ -1,13 +1,17 @@
 //! Configuration for fuzz testing.
 
-use crate::inline::{
-    parse_config_u32, InlineConfigParser, InlineConfigParserError, INLINE_CONFIG_FUZZ_KEY,
+use crate::{
+    inline::{
+        parse_config_u32, InlineConfigParser, InlineConfigParserError, INLINE_CONFIG_FUZZ_KEY,
+    },
+    Config,
 };
 use alloy_primitives::U256;
 use serde::{Deserialize, Serialize};
+use std::path::PathBuf;
 
 /// Contains for fuzz testing
-#[derive(Clone, Copy, Debug, PartialEq, Eq, Serialize, Deserialize)]
+#[derive(Clone, Debug, PartialEq, Eq, Serialize, Deserialize)]
 pub struct FuzzConfig {
     /// The number of test cases that must execute for each property test
     pub runs: u32,
@@ -22,6 +26,10 @@ pub struct FuzzConfig {
     /// The fuzz dictionary configuration
     #[serde(flatten)]
     pub dictionary: FuzzDictionaryConfig,
+    /// Path where fuzz failures are recorded and replayed, defaults to `~/.foundry/cache/fuzz`
+    pub failure_persist_dir: PathBuf,
+    /// Name of the file to record fuzz failures, defaults to `failures`
+    pub failure_persist_file: String,
 }
 
 impl Default for FuzzConfig {
@@ -31,6 +39,8 @@ impl Default for FuzzConfig {
             max_test_rejects: 65536,
             seed: None,
             dictionary: FuzzDictionaryConfig::default(),
+            failure_persist_dir: Config::foundry_fuzz_cache_dir().unwrap(),
+            failure_persist_file: "failures".to_string(),
         }
     }
 }
@@ -47,8 +57,7 @@ impl InlineConfigParser for FuzzConfig {
             return Ok(None)
         }
 
-        // self is Copy. We clone it with dereference.
-        let mut conf_clone = *self;
+        let mut conf_clone = self.clone();
 
         for pair in overrides {
             let key = pair.0;
@@ -59,6 +68,7 @@ impl InlineConfigParser for FuzzConfig {
                 "dictionary-weight" => {
                     conf_clone.dictionary.dictionary_weight = parse_config_u32(key, value)?
                 }
+                "failure-persist-file" => conf_clone.failure_persist_file = value,
                 _ => Err(InlineConfigParserError::InvalidConfigProperty(key))?,
             }
         }
@@ -127,11 +137,13 @@ mod tests {
         let configs = &[
             "forge-config: default.fuzz.runs = 42424242".to_string(),
             "forge-config: default.fuzz.dictionary-weight = 42".to_string(),
+            "forge-config: default.fuzz.failure-persist-file = fuzz-failure".to_string(),
         ];
         let base_config = FuzzConfig::default();
         let merged: FuzzConfig = base_config.try_merge(configs).expect("No errors").unwrap();
         assert_eq!(merged.runs, 42424242);
         assert_eq!(merged.dictionary.dictionary_weight, 42);
+        assert_eq!(merged.failure_persist_file, "fuzz-failure".to_string());
     }
 
     #[test]

crates/config/src/lib.rs

@@ -1349,6 +1349,11 @@ impl Config {
         Some(Self::foundry_cache_dir()?.join("etherscan"))
     }
 
+    /// Returns the path to foundry fuzz cache dir `~/.foundry/cache/fuzz`
+    pub fn foundry_fuzz_cache_dir() -> Option<PathBuf> {
+        Some(Self::foundry_cache_dir()?.join("fuzz"))
+    }
+
     /// Returns the path to foundry's keystores dir `~/.foundry/keystores`
     pub fn foundry_keystores_dir() -> Option<PathBuf> {
         Some(Self::foundry_dir()?.join("keystores"))

crates/forge/bin/cmd/test/mod.rs

@@ -99,6 +99,10 @@ pub struct TestArgs {
     #[arg(long, env = "FOUNDRY_FUZZ_RUNS", value_name = "RUNS")]
     pub fuzz_runs: Option<u64>,
 
+    /// File to rerun fuzz failures from.
+    #[arg(long)]
+    pub fuzz_input_file: Option<String>,
+
     #[command(flatten)]
     filter: FilterArgs,
 
@@ -174,7 +178,7 @@ impl TestArgs {
         let profiles = get_available_profiles(toml)?;
 
         let test_options: TestOptions = TestOptionsBuilder::default()
-            .fuzz(config.fuzz)
+            .fuzz(config.clone().fuzz)
             .invariant(config.invariant)
             .profiles(profiles)
             .build(&output, project_root)?;
@@ -492,6 +496,9 @@ impl Provider for TestArgs {
         if let Some(fuzz_runs) = self.fuzz_runs {
             fuzz_dict.insert("runs".to_string(), fuzz_runs.into());
         }
+        if let Some(fuzz_input_file) = self.fuzz_input_file.clone() {
+            fuzz_dict.insert("failure_persist_file".to_string(), fuzz_input_file.into());
+        }
         dict.insert("fuzz".to_string(), fuzz_dict.into());
 
         if let Some(etherscan_api_key) =

crates/forge/src/lib.rs

@@ -6,7 +6,9 @@ use foundry_config::{
     validate_profiles, Config, FuzzConfig, InlineConfig, InlineConfigError, InlineConfigParser,
     InvariantConfig, NatSpec,
 };
-use proptest::test_runner::{RngAlgorithm, TestRng, TestRunner};
+use proptest::test_runner::{
+    FailurePersistence, FileFailurePersistence, RngAlgorithm, TestRng, TestRunner,
+};
 use std::path::Path;
 
 pub mod coverage;
@@ -93,8 +95,17 @@ impl TestOptions {
     where
         S: Into<String>,
     {
-        let fuzz = self.fuzz_config(contract_id, test_fn);
-        self.fuzzer_with_cases(fuzz.runs)
+        let fuzz_config = self.fuzz_config(contract_id, test_fn).clone();
+        let failure_persist_path = fuzz_config
+            .failure_persist_dir
+            .join(fuzz_config.failure_persist_file)
+            .into_os_string()
+            .into_string()
+            .unwrap();
+        self.fuzzer_with_cases(
+            fuzz_config.runs,
+            Some(Box::new(FileFailurePersistence::Direct(failure_persist_path.leak()))),
+        )
     }
 
     /// Returns an "invariant" test runner instance. Parameters are used to select tight scoped fuzz
@@ -109,7 +120,7 @@ impl TestOptions {
         S: Into<String>,
     {
         let invariant = self.invariant_config(contract_id, test_fn);
-        self.fuzzer_with_cases(invariant.runs)
+        self.fuzzer_with_cases(invariant.runs, None)
     }
 
     /// Returns a "fuzz" configuration setup. Parameters are used to select tight scoped fuzz
@@ -140,10 +151,13 @@ impl TestOptions {
         self.inline_invariant.get(contract_id, test_fn).unwrap_or(&self.invariant)
     }
 
-    pub fn fuzzer_with_cases(&self, cases: u32) -> TestRunner {
-        // TODO: Add Options to modify the persistence
+    pub fn fuzzer_with_cases(
+        &self,
+        cases: u32,
+        file_failure_persistence: Option<Box<dyn FailurePersistence>>,
+    ) -> TestRunner {
         let config = proptest::test_runner::Config {
-            failure_persistence: None,
+            failure_persistence: file_failure_persistence,
             cases,
             max_global_rejects: self.fuzz.max_test_rejects,
             ..Default::default()

crates/forge/src/runner.rs

@@ -294,7 +294,7 @@ impl<'a> ContractRunner<'a> {
                     debug_assert!(func.is_test());
                     let runner = test_options.fuzz_runner(self.name, &func.name);
                     let fuzz_config = test_options.fuzz_config(self.name, &func.name);
-                    self.run_fuzz_test(func, should_fail, runner, setup, *fuzz_config)
+                    self.run_fuzz_test(func, should_fail, runner, setup, fuzz_config.clone())
                 } else {
                     debug_assert!(func.is_test());
                     self.run_test(func, should_fail, setup)
@@ -601,8 +601,12 @@ impl<'a> ContractRunner<'a> {
 
         // Run fuzz test
         let start = Instant::now();
-        let fuzzed_executor =
-            FuzzedExecutor::new(self.executor.clone(), runner.clone(), self.sender, fuzz_config);
+        let fuzzed_executor = FuzzedExecutor::new(
+            self.executor.clone(),
+            runner.clone(),
+            self.sender,
+            fuzz_config.clone(),
+        );
         let state = fuzzed_executor.build_fuzz_state();
         let result = fuzzed_executor.fuzz(func, address, should_fail, self.revert_decoder);
 

crates/forge/tests/it/fuzz.rs

@@ -1,10 +1,14 @@
 //! Fuzz tests.
 
-use crate::config::*;
-use alloy_primitives::U256;
+use std::collections::BTreeMap;
+
+use alloy_primitives::{Bytes, U256};
+use forge::fuzz::CounterExample;
+
 use forge::result::{SuiteResult, TestStatus};
 use foundry_test_utils::Filter;
-use std::collections::BTreeMap;
+
+use crate::config::*;
 
 #[tokio::test(flavor = "multi_thread")]
 async fn test_fuzz() {
@@ -103,3 +107,50 @@ async fn test_fuzz_collection() {
         )]),
     );
 }
+
+#[tokio::test(flavor = "multi_thread")]
+async fn test_persist_fuzz_failure() {
+    let filter = Filter::new(".*", ".*", ".*fuzz/FuzzFailurePersist.t.sol");
+    let mut runner = runner();
+    runner.test_options.fuzz.runs = 1000;
+
+    macro_rules! get_failure_result {
+        () => {
+            runner
+                .test_collect(&filter)
+                .get("fuzz/FuzzFailurePersist.t.sol:FuzzFailurePersistTest")
+                .unwrap()
+                .test_results
+                .get("test_persist_fuzzed_failure(uint256,int256,address,bool,string,(address,uint256),address[])")
+                .unwrap()
+                .counterexample
+                .clone()
+        };
+    }
+
+    // record initial counterexample calldata
+    let intial_counterexample = get_failure_result!();
+    let initial_calldata = match intial_counterexample {
+        Some(CounterExample::Single(counterexample)) => counterexample.calldata,
+        _ => Bytes::new(),
+    };
+
+    // run several times and compare counterexamples calldata
+    for _ in 0..10 {
+        let new_calldata = match get_failure_result!() {
+            Some(CounterExample::Single(counterexample)) => counterexample.calldata,
+            _ => Bytes::new(),
+        };
+        // calldata should be the same with the initial one
+        assert_eq!(initial_calldata, new_calldata);
+    }
+
+    // write new failure in different file
+    runner.test_options.fuzz.failure_persist_file = "failure1".to_string();
+    let new_calldata = match get_failure_result!() {
+        Some(CounterExample::Single(counterexample)) => counterexample.calldata,
+        _ => Bytes::new(),
+    };
+    // empty file is used to load failure so new calldata is generated
+    assert_ne!(initial_calldata, new_calldata);
+}

crates/forge/tests/it/test_helpers.rs

@@ -94,6 +94,8 @@ pub static TEST_OPTS: Lazy<TestOptions> = Lazy::new(|| {
                 max_fuzz_dictionary_values: 10_000,
                 max_calldata_fuzz_dictionary_addresses: 0,
             },
+            failure_persist_dir: tempfile::tempdir().unwrap().into_path(),
+            failure_persist_file: "testfailure".to_string(),
         })
         .invariant(InvariantConfig {
             runs: 256,
@@ -124,6 +126,6 @@ pub fn fuzz_executor<DB: DatabaseRef>(executor: Executor) -> FuzzedExecutor {
         executor,
         proptest::test_runner::TestRunner::new(cfg),
         CALLER,
-        TEST_OPTS.fuzz,
+        TEST_OPTS.fuzz.clone(),
     )
 }

testdata/fuzz/FuzzFailurePersist.t.sol

@@ -0,0 +1,29 @@
+// SPDX-License-Identifier: MIT OR Apache-2.0
+pragma solidity 0.8.18;
+
+import "ds-test/test.sol";
+import "../cheats/Vm.sol";
+
+struct TestTuple {
+    address user;
+    uint256 amount;
+}
+
+contract FuzzFailurePersistTest is DSTest {
+    Vm vm = Vm(HEVM_ADDRESS);
+
+    function test_persist_fuzzed_failure(
+        uint256 x,
+        int256 y,
+        address addr,
+        bool cond,
+        string calldata test,
+        TestTuple calldata tuple,
+        address[] calldata addresses
+    ) public {
+        // dummy assume to trigger runs
+        vm.assume(x > 1 && x < 1111111111111111111111111111);
+        vm.assume(y > 1 && y < 1111111111111111111111111111);
+        require(false);
+    }
+}