Add test for POA error redundancy middleware.

tests/integration/network/test_poa_redundancy_middleware.py

@@ -0,0 +1,58 @@
+from unittest.mock import ANY, Mock
+
+from web3.exceptions import ExtraDataLengthError
+from web3.middleware import geth_poa_middleware
+from web3.types import RPCEndpoint, RPCResponse
+
+from nucypher.blockchain.middleware.poa import create_poa_error_redundancy_middleware
+
+
+def test_request_with_poa_issues():
+    make_request = Mock()
+    w3 = Mock()
+    middleware_onion = Mock()
+    w3.middleware_onion = middleware_onion
+
+    poa_name = "poa_test"
+
+    poa_redundancy_middleware = create_poa_error_redundancy_middleware(
+        existing_poa_middleware_name=poa_name
+    )
+
+    valid_response = RPCResponse(
+        jsonrpc="2.0", id=1, result="Geth/v1.14.8-stable-a9523b64/linux-amd64/go1.22.6"
+    )
+
+    redundant_middleware = poa_redundancy_middleware(make_request, w3)
+
+    # 1. no poa error, simply return response
+    make_request.side_effect = [valid_response]
+    response = redundant_middleware(RPCEndpoint("web3_clientVersion"), None)
+
+    assert response == valid_response
+    middleware_onion.get.assert_not_called()
+    middleware_onion.remove.assert_not_called()
+    middleware_onion.inject.assert_not_called()
+
+    # 2. poa error; no prior poa middleware
+    make_request.side_effect = [ExtraDataLengthError(), valid_response]
+    middleware_onion.get.return_value = None
+
+    response = redundant_middleware(RPCEndpoint("web3_clientVersion"), None)
+
+    assert response == valid_response
+    middleware_onion.get.assert_called_once_with(poa_name)
+    middleware_onion.remove.assert_not_called()
+    middleware_onion.inject.assert_called_once_with(ANY, layer=0, name=poa_name)
+
+    # 3. poa error; prior poa middleware
+    make_request.side_effect = [ExtraDataLengthError(), valid_response]
+    middleware_onion.get.return_value = geth_poa_middleware
+    response = redundant_middleware(RPCEndpoint("web3_clientVersion"), None)
+
+    assert response == valid_response
+    assert middleware_onion.get.call_count == 2
+    middleware_onion.get.assert_called_with(poa_name)
+    middleware_onion.remove.assert_called_once_with(poa_name)
+    assert middleware_onion.inject.call_count == 2
+    middleware_onion.inject.assert_called_with(ANY, layer=0, name=poa_name)