@Test
  public void testGetAsyncNullValue() throws Exception {
    String key = "NonExistingKey";
    Bucket bucket = mock(Bucket.class);
    AsyncBucket asyncBucket = mock(AsyncBucket.class);
    CouchbaseTableReadFunction readFunction = createAndInit(String.class, new StringSerde(), bucket, asyncBucket);
    when(asyncBucket.get(eq(key), anyObject(), anyLong(), any(TimeUnit.class))).thenReturn(Observable.empty());
    assertNull(readFunction.getAsync(key).get());
  }
This class performs unit tests for CouchbaseTableReadFunction.
samza-kv-couchbase/src/test/java/org/apache/samza/table/remote/couchbase/TestCouchbaseTableReadFunction.java