我想單擊一個單選按鈕，出現在網頁上。代碼如下：HTML代碼：<div class="small-checkbox red-theme raleway-regular text-muted2 position-relative">        <div class="city-checkbox inline-block position-relative" ng-class="{'rounded-checkbox': main.current_city_id == 1, 'mb-20': main.ifDeviceIsPhone}">            <label class="mdl-radio mdl-js-radio mdl-js-ripple-effect mh-20" for="mumbaiCity" ng-class="{'is-checked' : main.current_city_id == 1}">                <input type="radio" id="mumbaiCity" class="mdl-radio__button position-relative vertical-middle" name="city" value="1" ng-click="main.setCity('Mumbai', 1)">                <span class="mdl-radio__label position-relative font15"><img class="city-icon" src="../../../assets/img/cities/mumbai-icon.png">Mumbai</span>            </label>        </div></div>Tesstcase：// demo-test.jsdescribe('Protractor Demo App', function() {    jasmine.DEFAULT_TIMEOUT_INTERVAL = 10000000;    it('check item count', function() {        browser.get('<link>');        element(by.id('mumbaiCity')).click();    });});此測試通過錯誤：1）量角器演示應用檢查項目數信息：失敗：元素不可見我也嘗試過：element(by.css('[ng-click="main.setCity('Mumbai', 1)"]')).click();它給出了錯誤：[16:16:26] E / launcher-參數列表后出現錯誤：SyntaxError：缺少）請提出建議，單選按鈕將如何獲得點擊？