private void checkQueryableStore(final String queryableName, final TestRecord<Long, String> expectedFinalResult, final TopologyTestDriver driver) {
        final ReadOnlyKeyValueStore<Long, ValueAndTimestamp<String>> store = driver.getTimestampedKeyValueStore(queryableName);

        final KeyValueIterator<Long, ValueAndTimestamp<String>> all = store.all();
        final KeyValue<Long, ValueAndTimestamp<String>> onlyEntry = all.next();

        try {
            assertThat(onlyEntry.key, is(expectedFinalResult.key()));
            assertThat(onlyEntry.value.value(), is(expectedFinalResult.value()));
            assertThat(onlyEntry.value.timestamp(), is(expectedFinalResult.timestamp()));
            assertThat(all.hasNext(), is(false));
        } finally {
            all.close();
        }
    }
Tests all available joins of Kafka Streams DSL.
streams/src/test/java/org/apache/kafka/streams/integration/AbstractJoinIntegrationTest.java