Monkey patch to prevent gas estimates

nucypher/utilities/sandbox/blockchain.py

@@ -20,6 +20,7 @@ import os
 from typing import List, Tuple
 
 import maya
+from eth_tester.exceptions import TransactionFailed
 from twisted.logger import Logger
 from web3 import Web3
 
@@ -265,5 +266,7 @@ class TesterBlockchain(BlockchainDeployerInterface):
         """Wait for a transaction receipt and return it"""
         timeout = timeout or self.TIMEOUT
         result = self.w3.eth.waitForTransactionReceipt(txhash, timeout=timeout)
+        if result.status == 0:
+            raise TransactionFailed()
         return result
 

tests/fixtures.py

@@ -369,6 +369,14 @@ def _make_testerchain():
     eth._utils.headers.GAS_LIMIT_MINIMUM = TEST_GAS_LIMIT
     eth._utils.headers.GENESIS_GAS_LIMIT = TEST_GAS_LIMIT
     eth.vm.forks.frontier.headers.GENESIS_GAS_LIMIT = TEST_GAS_LIMIT
+
+    # Monkey patch to prevent gas estimates
+    def _get_buffered_gas_estimate(web3, transaction, gas_buffer=100000):
+        return TEST_GAS_LIMIT
+
+    import web3
+    web3.eth.get_buffered_gas_estimate = _get_buffered_gas_estimate
+
     # Create the blockchain
     testerchain = TesterBlockchain(eth_airdrop=True, free_transactions=True)
     BlockchainInterfaceFactory.register_interface(interface=testerchain)