IsNullEvaluator extends Evaluator<T> { @Override protected TruthValue evaluate(T value) { if (value == null) { return TruthValue.YES; } return TruthValue.NO; } IsNullEvaluator(String fieldName);   }
@Test public void stringIsNotNull() { when(corc.getWritable(COL0)).thenReturn(FOO); assertThat(evaluator.evaluate(corc), is(TruthValue.NO)); }
@Test public void stringIsNull() { when(corc.getWritable(COL0)).thenReturn(null); assertThat(evaluator.evaluate(corc), is(TruthValue.YES)); }