groovyEngine = new GroovyEngine();
    }

    @Override
    public void tearDown() throws Exception {
        ComponentUtil.setFessConfig(null);
        super.tearDown();
    }

    public void test_evaluate() {
        final Map<String, Object> params = new HashMap<>();
        assertNull(groovyEngine.evaluate("", params));
        assertEquals("", groovyEngine.evaluate("return ''", params));