@Test
public void testTransformOperator()
{

  // Set expression map
  Map<String, String> expMap = new HashMap<>();
  expMap.put("var21", "var1");
  expMap.put("var22", "$.var2");
  expMap.put("var23", "{$.var3}");
  operator.setExpressionMap(expMap);
  operator.activate(null);
  operator.beginWindow(1L);
  InputClass inputClass = new InputClass();
  inputClass.setVar1(123);
  inputClass.setVar2(12);
  inputClass.setVar3("ABC");
  operator.input.put(inputClass);
  operator.endWindow();
  Assert.assertEquals(1, sink.collectedTuples.size());
  Object o = sink.collectedTuples.get(0);
  Assert.assertTrue(o instanceof OutputClass);
  OutputClass out = (OutputClass)o;
  Assert.assertEquals(123, out.getVar21());
  Assert.assertEquals(12, out.getVar22());
  Assert.assertEquals("ABC", out.getVar23());
}