fix: allow empty fork config to default to empty dict (#102)

ape_foundry/provider.py

@@ -43,7 +43,7 @@
 from evm_trace import CallType, ParityTraceList
 from evm_trace import TraceFrame as EvmTraceFrame
 from evm_trace import get_calltree_from_geth_trace, get_calltree_from_parity_trace
-from pydantic import model_validator
+from pydantic import field_validator, model_validator
 from pydantic_settings import SettingsConfigDict
 from web3 import HTTPProvider, Web3
 from web3.exceptions import ContractCustomError
@@ -96,10 +96,10 @@ class FoundryNetworkConfig(PluginConfig):
     # Mapping of ecosystem_name => network_name => FoundryForkConfig
     fork: Dict[str, Dict[str, FoundryForkConfig]] = {}
 
+    disable_block_gas_limit: bool = False
     """
     Disable the ``call.gas_limit <= block.gas_limit`` constraint.
     """
-    disable_block_gas_limit: bool = False
 
     auto_mine: bool = True
     """
@@ -111,8 +111,14 @@ class FoundryNetworkConfig(PluginConfig):
     Set a block time to allow mining to happen on an interval
     rather than only when a new transaction is submitted.
     """
+
     model_config = SettingsConfigDict(extra="allow")
 
+    @field_validator("fork", mode="before")
+    @classmethod
+    def _validate_fork(cls, value):
+        return value or {}
+
 
 def _call(*args):
     return call([*args], stderr=PIPE, stdout=PIPE, stdin=PIPE)

tests/test_provider.py

@@ -14,7 +14,7 @@
 from hexbytes import HexBytes
 
 from ape_foundry import FoundryProviderError
-from ape_foundry.provider import FOUNDRY_CHAIN_ID, _extract_custom_error
+from ape_foundry.provider import FOUNDRY_CHAIN_ID, FoundryNetworkConfig, _extract_custom_error
 
 TEST_WALLET_ADDRESS = "0xD9b7fdb3FC0A0Aa3A507dCf0976bc23D49a9C7A3"
 
@@ -490,3 +490,8 @@ def trace(txn_hash: str, *args, **kwargs):
 
     # Show failure was tracked
     assert tracker[0] == HexBytes(tx.txn_hash).hex()
+
+
+def test_fork_config_none():
+    cfg = FoundryNetworkConfig.model_validate({"fork": None})
+    assert isinstance(cfg["fork"], dict)