在 Jasmine 测试中更新 React 组件状态

Question

我有一个相对简单的 React 组件，它根据其状态呈现一个列表。然后我有一个 karma/jasmine 测试来呈现组件，设置它的状态，并检查是否呈现了正确的标记。

我遇到的问题是，每次我在组件上执行 setState({}) 或 forceUpdate() 时，都会出现错误：

TypeError: 'undefined' is not an object (evaluating 'deepestAncestor.firstChild')
        at /home/company/projects/user_interface_kit/bower_components/react/react.js:10314

在 React 组件中测试状态变化的正确方法是什么？

反应代码：

    var NotificationCenter = React.createClass({

        getInitialState: function(){
            return {notifications:[]}
        },


        render: function() {            

                countContainerStyle = {
                    display: this.state.notifications.length > 0 ? '' : 'none'
                };


            return (
                <div id="pc-notification-center">
                    <span className="pc-notification-center-bell" >
                        B
                    </span>
                    <span className="pc-notification-count-container" style={countContainerStyle}>
                        <span className="pc-notification-count-circle">&#9679;</span>
                        <span className="pc-notification-count">{this.state.notifications.length}</span>
                    </span>
                </div>);
        }

    });

    return NotificationCenter;
});

测试代码：

it('should set its notification count to the number of notifications it has', function() {
        var notificationCenter = NotificationCenter({}),
            countNode;

        TestUtils.renderIntoDocument(notificationCenter);

        notificationCenter.setState({
            notifications: [1,2]
        });


        countNode = TestUtils.findRenderedDOMComponentWithClass(notificationCenter,'pc-notification-count');


        expect(countNode).toBe(2);
    });

编辑：完整堆栈跟踪

PhantomJS 1.9.7 (Linux) [object Object] [object Object] [object Object] should default its notification count to 0 FAILED
TypeError: 'undefined' is not an object (evaluating 'deepestAncestor.firstChild')
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10314
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10260
    at getNode (/home/company/projects/user_interface_kit/bower_components/react/react.js:9874)
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:4472
    at /home/company/projects/user_interface_kit/.tmp/notification_center/popover.js:28
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:5925
    at /home/company/projects/user_interface_kit/.tmp/notification_center/popover.js:75
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:5925
    at /home/company/projects/user_interface_kit/.tmp/notification_center/popover.js:81
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10461
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11924
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13944
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13877
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:4360
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10055
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11169
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10105
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11169
    at /home/company/projects/user_interface_kit/.tmp/notification_center/notification_center.js:50
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10461
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11924
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13944
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13877
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:4360
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:10483
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:11597
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:10533
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:11597
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:12716
    at /home/company/projects/user_interface_kit/test/notification_center/notification_center_test.js:19
    at /home/company/projects/user_interface_kit/node_modules/karma-jasmine/lib/adapter.js:171
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1585
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:841
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1104
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:754
    at callGetModule (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1129)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1479
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1606

这是一个重现问题的小项目 https://github.com/treehau5/react_karma_requirejs_bug_reproduction

Answer 1

这是 renderIntoDocument 源代码（我在项目中使用的 React 0.14.8）： https://github.com/facebook/react/blob/v0.14.8/src/test/ReactTestUtils.js#L79

这是在 2 年前更改的时间：https://github.com/facebook/react/commit/ce95c3d042309d8aced894cc6be43d7e4cf96455

因此，尽管有名称，但它实际上并没有将任何内容呈现到文档中。

我还可以确认 Assaf 的答案仍然适用于 0.14.8 - 基本上，编写您自己的 renderIntoDocument。这对我有用：

function renderIntoDocument (instance) {
    var div = document.createElement('div');
    document.documentElement.appendChild(div);
    return ReactDOM.render(instance, div);
}

Answer 2

你仍然可以使用原来的TestUtils.renderIntoDocument，只需要将需要的React 移到beforeEach 中。因为如果你需要全局 React，每个测试的上下文都会不同，这会导致 2 个不同的实例挂载同一个组件。

beforeEach(function () {
    React = require('react/addons');
    TestUtils = React.addons.TestUtils;
});

Answer 3

我不知道之前的答案是否仍然正确。

使用 React 0.11.1，这段代码可以正常工作：

var React = require('react/addons');
var TestUtils = React.addons.TestUtils;

jest.dontMock('public/components/MyThing.jsx');
var MyThing = require('public/components/MyThing.jsx');

describe('MyThing', function() {
  var html;

  describe('#render', function() {
    beforeEach(function(){
      var component = MyThing();
      var componentInstance = TestUtils.renderIntoDocument(component);
      componentInstance.setState({isCool: true});

      html = componentInstance.getDOMNode().textContent;
    });

    it('includes something cool', function(){
      expect(html).toContain('something cool');
    });
  });
});

Answer 4

在深入研究了 React 和 React_with_addons 的工作原理之后，看起来测试中的本地 React 对象与 React_with_addons 使用的 React 实例不同。因此，如果您在测试中这样做：

react_with_addons.addons.TestUtils.renderIntoDocument(componentInstance);

然后 react_with_addon 的 React 实例注册 componentInstance 并初始化它的 nodeCache 对象。本地 React 实例保持不变。然后，如果您尝试像这样更新组件的状态：

componentInstance.updateState({key:'newValue'});

React 的本地实例用于尝试更新 DOM。由于此实例从未挂载过任何组件，因此更新失败，您会收到“未定义”不是对象（正在评估“deepestAncestor.firstChild”）错误。

有趣的是，如果您将任何组件安装到本地 React 中，那么在更新组件的状态时您不会看到错误，即使该组件是使用 react_with_addon 的 React 对象安装的。

如果您的测试需要运行 setState，目前避免此问题的最佳方法是不使用 react_with_addon 的 renderIntoDocument 函数。相反，只需创建自己的。它只有两行：

 function renderIntoDocument(instance) {
        var div = document.createElement('div');
        return React.renderComponent(instance, div);
      };