private FetchCollector<String, String> createFetchCollector(final SubscriptionState subscriptions) {
        final Properties consumerProps = consumerProps();
        return new FetchCollector<>(
            logContext,
            mock(ConsumerMetadata.class),
            subscriptions,
            new FetchConfig(new ConsumerConfig(consumerProps)),
            new Deserializers<>(new StringDeserializer(), new StringDeserializer()),
            mock(FetchMetricsManager.class),
            new MockTime()
        );
    }
This tests the {@link FetchCollector} functionality in addition to what {@link FetcherTest} tests during the course
of its tests.
clients/src/test/java/org/apache/kafka/clients/consumer/internals/FetchCollectorTest.java