@Test
public void testJoinTransformWithOneMetric() {

    Transform joinTransform = new JoinTransform();
    Map<Long, Double> datapoints_1 = new HashMap<Long, Double>();
    datapoints_1.put(1000L, 1.0);
    datapoints_1.put(2000L, 2.0);
    datapoints_1.put(3000L, 3.0);
    Metric metric_1 = new Metric(TEST_SCOPE, TEST_METRIC);
    metric_1.setDatapoints(datapoints_1);
    List<Metric> metrics = new ArrayList<Metric>();
    metrics.add(metric_1);
    Map<Long, Double> expected = new HashMap<Long, Double>();
    expected.put(1000L, 1.0);
    expected.put(2000L, 2.0);
    expected.put(3000L, 3.0);
    List<Metric> result = joinTransform.transform(null, metrics);
    assertEquals(result.get(0).getDatapoints().size(), 3);
    assertEquals(expected, result.get(0).getDatapoints());
}