foundry_evm_fuzz/strategies/
invariants.rs

1use super::{fuzz_calldata, fuzz_param_from_state};
2use crate::{
3    BasicTxDetails, CallDetails, FuzzFixtures,
4    invariant::{FuzzRunIdentifiedContracts, SenderFilters},
5    strategies::{EvmFuzzState, fuzz_calldata_from_state, fuzz_param},
6};
7use alloy_json_abi::Function;
8use alloy_primitives::{Address, U256};
9use foundry_config::InvariantConfig;
10use parking_lot::RwLock;
11use proptest::prelude::*;
12use rand::seq::IteratorRandom;
13use std::{rc::Rc, sync::Arc};
14
15/// Given a target address, we generate random calldata.
16pub fn override_call_strat(
17    fuzz_state: EvmFuzzState,
18    contracts: FuzzRunIdentifiedContracts,
19    target: Arc<RwLock<Address>>,
20    fuzz_fixtures: FuzzFixtures,
21) -> impl Strategy<Value = CallDetails> + Send + Sync + 'static {
22    let contracts_ref = contracts.targets.clone();
23    proptest::prop_oneof![
24        80 => proptest::strategy::LazyJust::new(move || *target.read()),
25        20 => any::<prop::sample::Selector>()
26            .prop_map(move |selector| *selector.select(contracts_ref.lock().keys())),
27    ]
28    .prop_flat_map(move |target_address| {
29        let fuzz_state = fuzz_state.clone();
30        let fuzz_fixtures = fuzz_fixtures.clone();
31
32        let func = {
33            let contracts = contracts.targets.lock();
34            let contract = contracts.get(&target_address).unwrap_or_else(|| {
35                // Choose a random contract if target selected by lazy strategy is not in fuzz run
36                // identified contracts. This can happen when contract is created in `setUp` call
37                // but is not included in targetContracts.
38                contracts.values().choose(&mut rand::rng()).unwrap()
39            });
40            let fuzzed_functions: Vec<_> = contract.abi_fuzzed_functions().cloned().collect();
41            any::<prop::sample::Index>().prop_map(move |index| index.get(&fuzzed_functions).clone())
42        };
43
44        func.prop_flat_map(move |func| {
45            fuzz_contract_with_calldata(&fuzz_state, &fuzz_fixtures, target_address, func)
46        })
47    })
48}
49
50/// Creates the invariant strategy.
51///
52/// Given the known and future contracts, it generates the next call by fuzzing the `caller`,
53/// `calldata` and `target`. The generated data is evaluated lazily for every single call to fully
54/// leverage the evolving fuzz dictionary.
55///
56/// The fuzzed parameters can be filtered through different methods implemented in the test
57/// contract:
58///
59/// `targetContracts()`, `targetSenders()`, `excludeContracts()`, `targetSelectors()`
60pub fn invariant_strat(
61    fuzz_state: EvmFuzzState,
62    senders: SenderFilters,
63    contracts: FuzzRunIdentifiedContracts,
64    config: InvariantConfig,
65    fuzz_fixtures: FuzzFixtures,
66) -> impl Strategy<Value = BasicTxDetails> {
67    let senders = Rc::new(senders);
68    let dictionary_weight = config.dictionary.dictionary_weight;
69
70    // Strategy to generate values for tx warp and roll.
71    let warp_roll_strat = |cond: bool| {
72        if cond { any::<U256>().prop_map(Some).boxed() } else { Just(None).boxed() }
73    };
74
75    any::<prop::sample::Selector>()
76        .prop_flat_map(move |selector| {
77            let contracts = contracts.targets.lock();
78            let functions = contracts.fuzzed_functions();
79            let (target_address, target_function) = selector.select(functions);
80
81            let sender = select_random_sender(&fuzz_state, senders.clone(), dictionary_weight);
82
83            let call_details = fuzz_contract_with_calldata(
84                &fuzz_state,
85                &fuzz_fixtures,
86                *target_address,
87                target_function.clone(),
88            );
89
90            let warp = warp_roll_strat(config.max_time_delay.is_some());
91            let roll = warp_roll_strat(config.max_block_delay.is_some());
92
93            (warp, roll, sender, call_details)
94        })
95        .prop_map(move |(warp, roll, sender, call_details)| {
96            let warp =
97                warp.map(|time| time % U256::from(config.max_time_delay.unwrap_or_default()));
98            let roll =
99                roll.map(|block| block % U256::from(config.max_block_delay.unwrap_or_default()));
100            BasicTxDetails { warp, roll, sender, call_details }
101        })
102}
103
104/// Strategy to select a sender address:
105/// * If `senders` is empty, then it's either a random address (10%) or from the dictionary (90%).
106/// * If `senders` is not empty, a random address is chosen from the list of senders.
107fn select_random_sender(
108    fuzz_state: &EvmFuzzState,
109    senders: Rc<SenderFilters>,
110    dictionary_weight: u32,
111) -> impl Strategy<Value = Address> + use<> {
112    if !senders.targeted.is_empty() {
113        any::<prop::sample::Index>().prop_map(move |index| *index.get(&senders.targeted)).boxed()
114    } else {
115        assert!(dictionary_weight <= 100, "dictionary_weight must be <= 100");
116        proptest::prop_oneof![
117            100 - dictionary_weight => fuzz_param(&alloy_dyn_abi::DynSolType::Address),
118            dictionary_weight => fuzz_param_from_state(&alloy_dyn_abi::DynSolType::Address, fuzz_state),
119        ]
120        .prop_map(move |addr| {
121            let mut addr = addr.as_address().unwrap();
122            // Make sure the selected address is not in the list of excluded senders.
123            // We don't use proptest's filter to avoid reaching the `PROPTEST_MAX_LOCAL_REJECTS`
124            // max rejects and exiting test before all runs completes.
125            // See <https://github.com/foundry-rs/foundry/issues/11369>.
126            loop {
127                if !senders.excluded.contains(&addr) {
128                    break;
129                }
130                addr = Address::random();
131            }
132            addr
133        })
134        .boxed()
135    }
136}
137
138/// Given a function, it returns a proptest strategy which generates valid abi-encoded calldata
139/// for that function's input types.
140pub fn fuzz_contract_with_calldata(
141    fuzz_state: &EvmFuzzState,
142    fuzz_fixtures: &FuzzFixtures,
143    target: Address,
144    func: Function,
145) -> impl Strategy<Value = CallDetails> + use<> {
146    // We need to compose all the strategies generated for each parameter in all possible
147    // combinations.
148    // `prop_oneof!` / `TupleUnion` `Arc`s for cheap cloning.
149    prop_oneof![
150        60 => fuzz_calldata(func.clone(), fuzz_fixtures),
151        40 => fuzz_calldata_from_state(func, fuzz_state),
152    ]
153    .prop_map(move |calldata| {
154        trace!(input=?calldata);
155        CallDetails { target, calldata }
156    })
157}
foundry_evm_fuzz/strategies/invariants.rs

foundry_evm_fuzz/strategies/
invariants.rs
