add neuron certificate e2e test

bittensor/core/subtensor.py

@@ -1199,7 +1199,7 @@ def get_neuron_certificate(
         try:
             serialized_certificate = certificate.serialize()
             if serialized_certificate:
-                return serialized_certificate.get("certificate", None)
+                return chr(serialized_certificate["algorithm"]) + serialized_certificate["public_key"]
         except AttributeError:
             return None
 

tests/e2e_tests/test_neuron_certificate.py

@@ -0,0 +1,59 @@
+import pytest
+from bittensor.core.subtensor import Subtensor
+from bittensor.core.axon import Axon
+from bittensor.utils.btlogging import logging
+from tests.e2e_tests.utils.chain_interactions import (
+    wait_interval,
+    register_subnet,
+    register_neuron,
+)
+from tests.e2e_tests.utils.e2e_test_utils import (
+    setup_wallet,
+)
+
+
+@pytest.mark.asyncio
+async def test_neuron_certificate(local_chain):
+    """
+    Tests the metagraph
+
+    Steps:
+        1. Register a subnet through Alice
+        2. Serve Alice axon with neuron certificate
+        3. Verify neuron certificate can be retrieved
+    Raises:
+        AssertionError: If any of the checks or verifications fail
+    """
+    logging.info("Testing neuron_certificate")
+    netuid = 1
+
+    # Register root as Alice - the subnet owner and validator
+    alice_keypair, alice_wallet = setup_wallet("//Alice")
+    register_subnet(local_chain, alice_wallet)
+
+    # Verify subnet <netuid> created successfully
+    assert local_chain.query(
+        "SubtensorModule", "NetworksAdded", [netuid]
+    ).serialize(), "Subnet wasn't created successfully"
+
+    # Register Alice as a neuron on the subnet
+    register_neuron(local_chain, alice_wallet, netuid)
+
+    subtensor = Subtensor(network="ws://localhost:9945")
+
+    # Serve Alice's axon with a certificate
+    axon = Axon(wallet=alice_wallet)
+    encoded_certificate = "?FAKE_ALICE_CERT"
+    axon.serve(netuid=netuid, subtensor=subtensor, certificate=encoded_certificate)
+
+    await wait_interval(tempo=1, subtensor=subtensor, netuid=netuid)
+
+    # Verify we are getting the correct certificate
+    assert (
+        subtensor.get_neuron_certificate(
+            netuid=netuid, hotkey=alice_keypair.ss58_address
+        )
+        == encoded_certificate
+    )
+
+    logging.info("✅ Passed test_neuron_certificate")