Debugger Refactor #1: fuzz single (foundry-rs#5692)

* fuzz single refactor

* add struct docs

* Update crates/evm/src/fuzz/mod.rs

Co-authored-by: DaniPopes <57450786+DaniPopes@users.noreply.github.com>

* add docs and move types to types.rs

* fmt

* add docki docs

* fmt

---------

Co-authored-by: DaniPopes <57450786+DaniPopes@users.noreply.github.com>

Author: 2 people

crates/evm/src/fuzz/mod.rs

@@ -20,10 +20,12 @@ use strategies::{
     build_initial_state, collect_state_from_call, fuzz_calldata, fuzz_calldata_from_state,
     EvmFuzzState,
 };
+use types::{CaseOutcome, CounterExampleOutcome, FuzzCase, FuzzOutcome};
 
 pub mod error;
 pub mod invariant;
 pub mod strategies;
+pub mod types;
 
 /// Wrapper around an [`Executor`] which provides fuzzing support using [`proptest`](https://docs.rs/proptest/1.0.0/proptest/).
 ///
@@ -101,72 +103,45 @@ impl<'a> FuzzedExecutor<'a> {
         let strat = proptest::strategy::Union::new_weighted(weights);
         debug!(func = ?func.name, should_fail, "fuzzing");
         let run_result = self.runner.clone().run(&strat, |calldata| {
-            let call = self
-                .executor
-                .call_raw(self.sender, address, calldata.0.clone(), 0.into())
-                .map_err(|_| TestCaseError::fail(FuzzError::FailedContractCall))?;
-            let state_changeset = call
-                .state_changeset
-                .as_ref()
-                .ok_or_else(|| TestCaseError::fail(FuzzError::EmptyChangeset))?;
-
-            // Build fuzzer state
-            collect_state_from_call(
-                &call.logs,
-                state_changeset,
-                state.clone(),
-                &self.config.dictionary,
-            );
-
-            // When assume cheat code is triggered return a special string "FOUNDRY::ASSUME"
-            if call.result.as_ref() == ASSUME_MAGIC_RETURN_CODE {
-                return Err(TestCaseError::reject(FuzzError::AssumeReject))
-            }
-
-            let success = self.executor.is_success(
-                address,
-                call.reverted,
-                state_changeset.clone(),
-                should_fail,
-            );
-
-            if success {
-                let mut first_case = first_case.borrow_mut();
-                if first_case.is_none() {
-                    first_case.replace(FuzzCase {
-                        calldata,
-                        gas: call.gas_used,
-                        stipend: call.stipend,
-                    });
+            let fuzz_res = self.single_fuzz(&state, address, should_fail, calldata)?;
+
+            match fuzz_res {
+                FuzzOutcome::Case(case) => {
+                    let mut first_case = first_case.borrow_mut();
+                    gas_by_case.borrow_mut().push((case.case.gas, case.case.stipend));
+                    if first_case.is_none() {
+                        first_case.replace(case.case);
+                    }
+
+                    traces.replace(case.traces);
+
+                    if let Some(prev) = coverage.take() {
+                        // Safety: If `Option::or` evaluates to `Some`, then `call.coverage` must
+                        // necessarily also be `Some`
+                        coverage.replace(Some(prev.merge(case.coverage.unwrap())));
+                    } else {
+                        coverage.replace(case.coverage);
+                    }
+
+                    Ok(())
                 }
-                gas_by_case.borrow_mut().push((call.gas_used, call.stipend));
-
-                traces.replace(call.traces);
-
-                if let Some(prev) = coverage.take() {
-                    // Safety: If `Option::or` evaluates to `Some`, then `call.coverage` must
-                    // necessarily also be `Some`
-                    coverage.replace(Some(prev.merge(call.coverage.unwrap())));
-                } else {
-                    coverage.replace(call.coverage);
+                FuzzOutcome::CounterExample(CounterExampleOutcome {
+                    exit_reason,
+                    counterexample: _counterexample,
+                    ..
+                }) => {
+                    let status = exit_reason;
+                    // We cannot use the calldata returned by the test runner in `TestError::Fail`,
+                    // since that input represents the last run case, which may not correspond with
+                    // our failure - when a fuzz case fails, proptest will try
+                    // to run at least one more case to find a minimal failure
+                    // case.
+                    let call_res = _counterexample.1.result.clone();
+                    *counterexample.borrow_mut() = _counterexample;
+                    Err(TestCaseError::fail(
+                        decode::decode_revert(&call_res, errors, Some(status)).unwrap_or_default(),
+                    ))
                 }
-
-                Ok(())
-            } else {
-                let status = call.exit_reason;
-                // We cannot use the calldata returned by the test runner in `TestError::Fail`,
-                // since that input represents the last run case, which may not correspond with our
-                // failure - when a fuzz case fails, proptest will try to run at least one more
-                // case to find a minimal failure case.
-                *counterexample.borrow_mut() = (calldata, call);
-                Err(TestCaseError::fail(
-                    decode::decode_revert(
-                        counterexample.borrow().1.result.as_ref(),
-                        errors,
-                        Some(status),
-                    )
-                    .unwrap_or_default(),
-                ))
             }
         });
 
@@ -216,6 +191,63 @@ impl<'a> FuzzedExecutor<'a> {
 
         result
     }
+
+    /// Granular and single-step function that runs only one fuzz and returns either a `CaseOutcome`
+    /// or a `CounterExampleOutcome`
+    pub fn single_fuzz(
+        &self,
+        state: &EvmFuzzState,
+        address: Address,
+        should_fail: bool,
+        calldata: ethers::types::Bytes,
+    ) -> Result<FuzzOutcome, TestCaseError> {
+        let call = self
+            .executor
+            .call_raw(self.sender, address, calldata.0.clone(), 0.into())
+            .map_err(|_| TestCaseError::fail(FuzzError::FailedContractCall))?;
+        let state_changeset = call
+            .state_changeset
+            .as_ref()
+            .ok_or_else(|| TestCaseError::fail(FuzzError::EmptyChangeset))?;
+
+        // Build fuzzer state
+        collect_state_from_call(
+            &call.logs,
+            state_changeset,
+            state.clone(),
+            &self.config.dictionary,
+        );
+
+        // When assume cheat code is triggered return a special string "FOUNDRY::ASSUME"
+        if call.result.as_ref() == ASSUME_MAGIC_RETURN_CODE {
+            return Err(TestCaseError::reject(FuzzError::AssumeReject))
+        }
+
+        let breakpoints = call
+            .cheatcodes
+            .as_ref()
+            .map_or_else(Default::default, |cheats| cheats.breakpoints.clone());
+
+        let success =
+            self.executor.is_success(address, call.reverted, state_changeset.clone(), should_fail);
+
+        if success {
+            Ok(FuzzOutcome::Case(CaseOutcome {
+                case: FuzzCase { calldata, gas: call.gas_used, stipend: call.stipend },
+                traces: call.traces,
+                coverage: call.coverage,
+                debug: call.debug,
+                breakpoints,
+            }))
+        } else {
+            Ok(FuzzOutcome::CounterExample(CounterExampleOutcome {
+                debug: call.debug.clone(),
+                exit_reason: call.exit_reason,
+                counterexample: (calldata, call),
+                breakpoints,
+            }))
+        }
+    }
 }
 
 #[derive(Clone, Debug, Serialize, Deserialize)]
@@ -444,14 +476,3 @@ impl FuzzedCases {
         self.lowest().map(|c| c.gas).unwrap_or_default()
     }
 }
-
-/// Data of a single fuzz test case
-#[derive(Clone, Debug, Default, Serialize, Deserialize)]
-pub struct FuzzCase {
-    /// The calldata used for this fuzz test
-    pub calldata: Bytes,
-    /// Consumed gas
-    pub gas: u64,
-    /// The initial gas stipend for the transaction
-    pub stipend: u64,
-}

crates/evm/src/fuzz/types.rs

@@ -0,0 +1,51 @@
+use crate::{coverage::HitMaps, debug::DebugArena, executor::RawCallResult, trace::CallTraceArena};
+use ethers::types::Bytes;
+use foundry_common::evm::Breakpoints;
+use revm::interpreter::InstructionResult;
+use serde::{Deserialize, Serialize};
+
+/// Data of a single fuzz test case
+#[derive(Clone, Debug, Default, Serialize, Deserialize)]
+pub struct FuzzCase {
+    /// The calldata used for this fuzz test
+    pub calldata: Bytes,
+    /// Consumed gas
+    pub gas: u64,
+    /// The initial gas stipend for the transaction
+    pub stipend: u64,
+}
+
+/// Returned by a single fuzz in the case of a successful run
+#[derive(Debug)]
+pub struct CaseOutcome {
+    /// Data of a single fuzz test case
+    pub case: FuzzCase,
+    /// The traces of the call
+    pub traces: Option<CallTraceArena>,
+    /// The coverage info collected during the call
+    pub coverage: Option<HitMaps>,
+    /// The debug nodes of the call
+    pub debug: Option<DebugArena>,
+    /// Breakpoints char pc map
+    pub breakpoints: Breakpoints,
+}
+
+/// Returned by a single fuzz when a counterexample has been discovered
+#[derive(Debug)]
+pub struct CounterExampleOutcome {
+    /// Minimal reproduction test case for failing test
+    pub counterexample: (ethers::types::Bytes, RawCallResult),
+    /// The status of the call
+    pub exit_reason: InstructionResult,
+    /// The debug nodes of the call
+    pub debug: Option<DebugArena>,
+    /// Breakpoints char pc map
+    pub breakpoints: Breakpoints,
+}
+
+/// Outcome of a single fuzz
+#[derive(Debug)]
+pub enum FuzzOutcome {
+    Case(CaseOutcome),
+    CounterExample(CounterExampleOutcome),
+}

crates/forge/src/result.rs

@@ -6,7 +6,7 @@ use foundry_common::evm::Breakpoints;
 use foundry_evm::{
     coverage::HitMaps,
     executor::EvmError,
-    fuzz::{CounterExample, FuzzCase},
+    fuzz::{types::FuzzCase, CounterExample},
     trace::{TraceKind, Traces},
 };
 use serde::{Deserialize, Serialize};