def METHOD_NAME(test_registry, ursulas):
    ursula = random.choice(ursulas)
    collector = OperatorMetricsCollector(
        domain=ursula.domain,
        operator_address=ursula.operator_address,
        contract_registry=test_registry,
    )
    collector_registry = CollectorRegistry()
    prefix = 'test_worker_metrics_collector'
    collector.initialize(metrics_prefix=prefix, registry=collector_registry)
    collector.collect()
    operator_eth = collector_registry.get_sample_value(f"{prefix}_operator_eth_balance")
    # only floats can be stored
    assert operator_eth == float(ursula.eth_balance)