docBoostMatcher.setMatchExpression("true");
        assertFalse(docBoostMatcher.match(new HashMap<>()));
    }

    @Test
    public void test_match_nullExpression() {
        final DocBoostMatcher docBoostMatcher = new DocBoostMatcher();
        // matchExpression is null by default
        final Map<String, Object> map = new HashMap<String, Object>();