  @Test
  public void testAllNulls() {

    boolean shouldRead = new StrictMetricsEvaluator(SCHEMA, notNull("all_nulls")).eval(FILE);
    Assert.assertFalse("Should not match: no non-null value in all null column", shouldRead);

    shouldRead = new StrictMetricsEvaluator(SCHEMA, notNull("some_nulls")).eval(FILE);
    Assert.assertFalse("Should not match: column with some nulls contains a non-null value", shouldRead);

    shouldRead = new StrictMetricsEvaluator(SCHEMA, notNull("no_nulls")).eval(FILE);
    Assert.assertTrue("Should match: non-null column contains no null values", shouldRead);
  }