use pre-constructed providers, not uris.

nucypher/policy/conditions/evm.py

@@ -170,7 +170,7 @@ class RPCCondition(AccessControlCondition):
             )
         return method
 
-    def _next_endpoint(self, providers: Dict[int, Set[str]]) -> Iterator[HTTPProvider]:
+    def _next_endpoint(self, providers: Dict[int, Set[HTTPProvider]]) -> Iterator[HTTPProvider]:
         """Yields the next web3 provider to try for a given chain ID"""
         try:
             rpc_providers = providers[self.chain]
@@ -184,7 +184,7 @@ class RPCCondition(AccessControlCondition):
         for provider in rpc_providers:
             # Someday, we might make this whole function async, and then we can knock on
             # each endpoint here to see if it's alive and only yield it if it is.
-            yield HTTPProvider(endpoint_uri=provider)
+            yield provider
 
     def _configure_w3(self, provider: BaseProvider) -> Web3:
         # Instantiate a local web3 instance

tests/acceptance/conditions/test_multichain_evaluation.py

@@ -1,4 +1,7 @@
+from collections import defaultdict
+
 import pytest
+from web3 import HTTPProvider
 
 from nucypher.policy.conditions.evm import _CONDITION_CHAINS, RPCCondition
 from nucypher.policy.conditions.lingo import ConditionLingo
@@ -57,7 +60,7 @@ def multichain_ursulas(ursulas, chain_ids):
     base_uri = "tester://multichain.{}"
     provider_uris = [base_uri.format(i) for i in range(len(chain_ids))]
     mocked_condition_providers = {
-        cid: {uri} for cid, uri in zip(chain_ids, provider_uris)
+        cid: {HTTPProvider(uri)} for cid, uri in zip(chain_ids, provider_uris)
     }
     for ursula in ursulas:
         ursula.condition_providers = mocked_condition_providers
@@ -81,7 +84,7 @@ def mock_rpc_condition(module_mocker, testerchain):
 
 
 def test_single_retrieve_with_multichain_conditions(
-    enacted_policy, bob, multichain_ursulas, conditions, mock_rpc_condition
+    enacted_policy, bob, multichain_ursulas, conditions, mock_rpc_condition, mocker
 ):
     bob.remember_node(multichain_ursulas[0])
     bob.start_learning_loop()
@@ -98,3 +101,38 @@ def test_single_retrieve_with_multichain_conditions(
     )
 
     assert cleartexts == messages
+
+
+def test_single_decryption_request_with_faulty_rpc_endpoint(
+    enacted_policy, bob, multichain_ursulas, conditions, mock_rpc_condition
+):
+
+    bob.remember_node(multichain_ursulas[0])
+    bob.start_learning_loop()
+
+    messages, message_kits = make_message_kits(enacted_policy.public_key, conditions)
+    policy_info_kwargs = dict(
+        encrypted_treasure_map=enacted_policy.treasure_map,
+        alice_verifying_key=enacted_policy.publisher_verifying_key,
+    )
+
+    calls = defaultdict(int)
+    original_execute_call = RPCCondition._execute_call
+
+    def faulty_execute_call(*args, **kwargs):
+        """Intercept the call to the RPC endpoint and raise an exception on the second call."""
+        nonlocal calls
+        rpc_call = args[0]
+        calls[rpc_call.chain] += 1
+        if calls[rpc_call.chain] == 5:
+            raise Exception("Something went wrong")
+        return original_execute_call(*args, **kwargs)
+
+    RPCCondition._execute_call = faulty_execute_call
+    cleartexts = bob.retrieve_and_decrypt(
+        message_kits=message_kits,
+        **policy_info_kwargs,
+    )
+    assert cleartexts == messages
+    RPCCondition._execute_call = original_execute_call
+