@Test
public void validateCustomerSearchStepEmptySearchStringShouldFail() {

    formBean.validateCustomerSearchStep(validationContext);
    MessageContext messageContext = validationContext.getMessageContext();
    Message[] messages = messageContext.getAllMessages();
    Assert.assertEquals(1, messages.length);
    Message message = messages[0];
    Assert.assertEquals("searchString", message.getSource());
    verifyErrorMessage(NotEmpty.class, message);
}