Auto-detect 'file' uri scheme when an ipc file path is provided without a scheme and exists. This allows for auto-completion for file paths passed as --provider.

nucypher/blockchain/eth/interfaces.py

@@ -14,7 +14,7 @@ GNU Affero General Public License for more details.
 You should have received a copy of the GNU Affero General Public License
 along with nucypher.  If not, see <https://www.gnu.org/licenses/>.
 """
-
+import os
 import pprint
 import time
 from typing import List
@@ -55,8 +55,8 @@ from nucypher.blockchain.eth.providers import (
 )
 from nucypher.blockchain.eth.registry import EthereumContractRegistry
 from nucypher.blockchain.eth.sol.compile import SolidityCompiler
-from nucypher.crypto.powers import TransactingPower
 from nucypher.characters.control.emitters import StdoutEmitter
+from nucypher.crypto.powers import TransactingPower
 
 Web3Providers = Union[IPCProvider, WebsocketProvider, HTTPProvider, EthereumTester]
 
@@ -334,6 +334,14 @@ class BlockchainInterface:
                     'https': _get_HTTP_provider,
                 }
                 provider_scheme = uri_breakdown.scheme
+
+            # auto-detect for file based ipc
+            if not provider_scheme:
+                if os.path.exists(provider_uri):
+                    # file is available - assume ipc/file scheme
+                    self.log.info(f"Auto-detecting provider scheme as 'file://' for provider {provider_uri}")
+                    provider_scheme = 'file'
+
             try:
                 self._provider = providers[provider_scheme](provider_uri)
             except KeyError:

tests/blockchain/eth/clients/test_mocked_clients.py

@@ -1,5 +1,7 @@
 import datetime
+
 import pytest
+from web3 import HTTPProvider, IPCProvider
 
 from nucypher.blockchain.eth.clients import (
     Web3Client,
@@ -154,6 +156,26 @@ class BlockchainInterfaceTestBase(BlockchainInterface):
         pass
 
 
+class ProviderTypeTestClient(BlockchainInterfaceTestBase):
+    def __init__(self,
+                 expected_provider_class,
+                 actual_provider_to_attach,
+                 *args,
+                 **kwargs):
+        BlockchainInterfaceTestBase.__init__(self, *args, **kwargs)
+        self.expected_provider_class = expected_provider_class
+        self.test_provider_to_attach = actual_provider_to_attach
+
+    def _attach_provider(self, *args, **kwargs) -> None:
+        super()._attach_provider(*args, **kwargs)
+
+        if self.expected_provider_class is not None:
+            # check type
+            assert self.expected_provider_class == self.provider.__class__
+
+        super()._attach_provider(provider=self.test_provider_to_attach)
+
+
 class InfuraTestClient(BlockchainInterfaceTestBase):
 
     def _attach_provider(self, *args, **kwargs) -> None:
@@ -199,6 +221,55 @@ def test_geth_web3_client():
     assert interface.client.chain_id == 5  # Hardcoded above
 
 
+def test_autodetect_provider_type_file(tempfile_path):
+
+    interface = ProviderTypeTestClient(provider_uri=tempfile_path,  # existing file for test
+                                       expected_provider_class=IPCProvider,
+                                       actual_provider_to_attach=MockGethProvider())
+    interface.connect(fetch_registry=False, sync_now=False)
+    assert isinstance(interface.client, GethClient)
+
+
+def test_autodetect_provider_type_file_none_existent():
+    with pytest.raises(ValueError) as e:
+        interface = BlockchainInterfaceTestBase(provider_uri='/none_existent.ipc.geth')
+        interface.connect(fetch_registry=False, sync_now=False)
+
+    assert "invalid or unsupported blockchain provider URI" in str(e)
+
+
+def test_detect_provider_type_file():
+    interface = ProviderTypeTestClient(provider_uri='file:///ipc.geth',
+                                       expected_provider_class=IPCProvider,
+                                       actual_provider_to_attach=MockGethProvider())
+    interface.connect(fetch_registry=False, sync_now=False)
+    assert isinstance(interface.client, GethClient)
+
+
+def test_detect_provider_type_ipc():
+    interface = ProviderTypeTestClient(provider_uri='ipc:///ipc.geth',
+                                       expected_provider_class=IPCProvider,
+                                       actual_provider_to_attach=MockGethProvider())
+    interface.connect(fetch_registry=False, sync_now=False)
+    assert isinstance(interface.client, GethClient)
+
+
+def test_detect_provider_type_http():
+    interface = ProviderTypeTestClient(provider_uri='http://ganache:8445',
+                                       expected_provider_class=HTTPProvider,
+                                       actual_provider_to_attach=MockGanacheProvider())
+    interface.connect(fetch_registry=False, sync_now=False)
+    assert isinstance(interface.client, GanacheClient)
+
+
+def test_detect_provider_type_https():
+    interface = ProviderTypeTestClient(provider_uri='https://ganache:8445',
+                                       expected_provider_class=HTTPProvider,
+                                       actual_provider_to_attach=MockGanacheProvider())
+    interface.connect(fetch_registry=False, sync_now=False)
+    assert isinstance(interface.client, GanacheClient)
+
+
 def test_infura_web3_client():
     interface = InfuraTestClient(provider_uri='infura://1234567890987654321abcdef')
     interface.connect(fetch_registry=False, sync_now=False)