@Test(expected = IllegalArgumentException.class)
public void testPercentileTransformWithoutConstants() {

    Transform propagateTransform = new PropagateTransform();
    Metric metric = new Metric(TEST_SCOPE, TEST_METRIC);
    List<Metric> metrics = new ArrayList<Metric>();
    metrics.add(metric);
    List<String> constants = new ArrayList<String>();
    propagateTransform.transform(null, metrics, constants);
}