@Test
public void testSingleComparisonWithNullValue() throws ParserException {

    final RootNode root = parser.parse("eq(username,null)");
    assertThat(root).isNotNull();
    assertThat(root.getChildren().size()).isEqualTo(1);
    final SingleComparisonNode comparison = (SingleComparisonNode) root.getChildren().get(0);
    assertThat(comparison.getComparisonType()).isEqualTo(SingleComparisonNode.Type.EQ);
    assertThat(comparison.getComparisonProperty()).isEqualTo("username");
    assertThat(comparison.getComparisonValue()).isNull();
}