@Test
public void cleanExpression() {

    assertEquals("test", evaluator.cleanExpression(MVEL_ESCAPE_SYMBOL + "test"));
    assertEquals(" test", evaluator.cleanExpression(MVEL_ESCAPE_SYMBOL + " test"));
    assertEquals(" " + MVEL_ESCAPE_SYMBOL + " test", evaluator.cleanExpression(MVEL_ESCAPE_SYMBOL + " " + MVEL_ESCAPE_SYMBOL + " test"));
    assertEquals("test", evaluator.cleanExpression(new TextNode(MVEL_ESCAPE_SYMBOL + "test").toString()));
    assertEquals(" test", evaluator.cleanExpression(new TextNode(MVEL_ESCAPE_SYMBOL + " test").toString()));
    assertEquals(" " + MVEL_ESCAPE_SYMBOL + " test", evaluator.cleanExpression(new TextNode(MVEL_ESCAPE_SYMBOL + " " + MVEL_ESCAPE_SYMBOL + " test").toString()));
    assertThatThrownBy(() -> evaluator.cleanExpression("test"))
            .isInstanceOf(IllegalArgumentException.class)
            .hasMessageStartingWith("Malformed MVEL expression");
    assertThatThrownBy(() -> evaluator.cleanExpression(new TextNode("test").toString()))
            .isInstanceOf(IllegalArgumentException.class)
            .hasMessageStartingWith("Malformed MVEL expression");
}