public boolean eval(ContentFile<?> file) {
    // TODO: detect the case where a column is missing from the file using file's max field id.
    return new MetricsEvalVisitor().eval(file);
  }
@Test
  public void testMissingColumn() {
    assertThatThrownBy(() -> new StrictMetricsEvaluator(SCHEMA, lessThan("missing", 5)).eval(FILE))
        .isInstanceOf(ValidationException.class)
        .hasMessageContaining("Cannot find field 'missing'");
  }