Add worker_is_bonded static method and include in worker tests

nucypher/blockchain/eth/actors.py

@@ -1203,6 +1203,18 @@ class Worker(NucypherTokenActor):
             if start_working_now:
                 self.work_tracker.start(act_now=False)
 
+    @staticmethod
+    def worker_is_bonded(worker_address: str, registry: 'BaseContractRegistry') -> bool:
+        """
+        Checks that the Worker's bonded staking address isn't a null address
+        and returns a boolean.
+        """
+        staking_agent = ContractAgency.get_agent(StakingEscrowAgent,
+                                                 registry=registry)
+
+        staking_addr = staking_agent.get_staker_from_worker(worker_address)
+        return staking_addr != BlockchainInterface.NULL_ADDRESS
+
     @property
     def eth_balance(self) -> Decimal:
         """Return this workers's current ETH balance"""

tests/blockchain/eth/entities/actors/test_worker.py

@@ -3,6 +3,7 @@ import pytest_twisted
 from twisted.internet import threads
 from twisted.internet.task import Clock
 
+from nucypher.blockchain.eth.actors import Worker
 from nucypher.blockchain.eth.token import NU, WorkTracker
 from nucypher.crypto.powers import TransactingPower
 from nucypher.utilities.sandbox.constants import INSECURE_DEVELOPMENT_PASSWORD
@@ -31,9 +32,15 @@ def test_worker_auto_confirmations(testerchain,
     clock = Clock()
     WorkTracker.CLOCK = clock
 
+    # Check that the worker is unbonded
+    assert not Worker.worker_is_bonded(worker_address, test_registry)
+
     # Bond the Worker and Staker
     staker.set_worker(worker_address=worker_address)
 
+    # Ensure the worker is now bonded
+    assert Worker.worker_is_bonded(worker_address, test_registry)
+
     # Make the Worker
     ursula = make_decentralized_ursulas(ursula_config=ursula_decentralized_test_config,
                                         stakers_addresses=[staker.checksum_address],