DevExpress/testcafe-react-selectors

testcafe-react-selectors

This plugin provides selector extensions that make it easier to test ReactJS components with TestCafe. These extensions allow you to select page elements in a way that is native to React.

Install

$ npm install testcafe-react-selectors

Usage

• Wait for application to be ready to run tests
• Creating selectors for ReactJS components
  • Selecting elements by the component name
  • Selecting nested components
  • Selecting components by the component key
  • Selecting components by display name
  • Selecting components by property values
    • Properties whose values are objects
  • Searching for nested components
  • Combining with regular TestCafe selectors
• Obtaining component's props and state
• TypeScript Generic Selector
  • Composite Types in Props and State
• Limitations

Wait for application to be ready to run tests

To wait until the React's component tree is loaded, add the waitForReact method to fixture's beforeEach hook.

import { waitForReact } from 'testcafe-react-selectors';

fixture `App tests`
    .page('http://react-app-url')
    .beforeEach(async () => {
        await waitForReact();
    });

The default timeout for waitForReact is 10000 ms. You can specify a custom timeout value:

await waitForReact(5000);

If you need to call a selector from a Node.js callback, pass the current test controller as the second argument in the waitForReact function:

import { waitForReact } from 'testcafe-react-selectors';

fixture `App tests`
    .page('http://react-app-url')
    .beforeEach(async t => {
        await waitForReact(5000, t);
    });

The test controller will be assigned to the boundTestRun function's option. Otherwise, TestCafe would throw the following error: ClientFunction cannot implicitly resolve the test run in context of which it should be executed. See the TestCafe documentation for further details.

Creating selectors for ReactJS components

ReactSelector allows you to select page elements by the name of the component class or the nested component element.

Suppose you have the following JSX.

<TodoApp className="todo-app">
    <TodoInput />
    <TodoList>
        <TodoItem priority="High" key="HighPriority">Item 1</TodoItem>
        <TodoItem priority="Low" key="LowPriority">Item 2</TodoItem>
    </TodoList>

    <div className="items-count">Items count: <span>{this.state.itemCount}</span></div>
</TodoApp>

Selecting elements by the component name

To get a root DOM element for a component, pass the component name to the ReactSelector constructor.

import { ReactSelector } from 'testcafe-react-selectors';

const todoInput = ReactSelector('TodoInput');

Selecting nested components

To obtain a nested component or DOM element, you can use a combined selector or add DOM element's tag name.

import { ReactSelector } from 'testcafe-react-selectors';

const TodoList         = ReactSelector('TodoApp TodoList');
const itemsCountStatus = ReactSelector('TodoApp div');
const itemsCount       = ReactSelector('TodoApp div span');

Warning: if you specify a DOM element's tag name, React selectors search for the element among the component's children without looking into nested components. For instance, for the JSX above the ReactSelector('TodoApp div') selector will be equal to Selector('.todo-app > div').

Selecting components by the component key

To obtain a component by its key, use the withKey method.

import { ReactSelector } from 'testcafe-react-selectors';

const item = ReactSelector('TodoItem').withKey('HighPriority');

Selecting components by display name

You can select elements by the component's displayName.

For instance, consider the TodoList component whose displayName class property is specified as follows:

class TodoList extends React.Component {
  // ...
}

TodoList.displayName = 'TodoList';

In this instance, you can use todo-list-display-name to identify TodoList.

import { ReactSelector } from 'testcafe-react-selectors';

const list = ReactSelector('todo-list-display-name');

Selecting components by property values

React selectors allow you to select elements that have a specific property value. To do this, use the withProps method. You can pass the property and its value as two parameters or an object.

import { ReactSelector } from 'testcafe-react-selectors';

const item1 = ReactSelector('TodoApp').withProps('priority', 'High');
const item2 = ReactSelector('TodoApp').withProps({ priority: 'Low' });

You can also search for elements by multiple properties.

import { ReactSelector } from 'testcafe-react-selectors';

const element = ReactSelector('componentName').withProps({
    propName: 'value',
    anotherPropName: 'differentValue'
});

Properties whose values are objects

React selectors allow you to filter components by properties whose values are objects.

When the withProps function filters properties, it determines whether the objects (property values) are strictly or partially equal.

The following example illustrates strict and partial equality.

object1 = {
    field1: 1
}
object2 = {
    field1: 1
}
object3 = {
    field1: 1
    field2: 2
}
object4 = {
    field1: 3
    field2: 2
}

• object1 strictly equals object2
• object2 partially equals object3
• object2 does not equal object4
• object3 does not equal object4

Prior to version 3.0.0, withProps checked if objects are strictly equal when comparing them. Since 3.0.0, withProps checks for partial equality. To test objects for strict equality, specify the exactObjectMatch option.

The following example returns the componentName component because the objProp property values are strictly equal and exactObjectMatch is set to true.

// props = {
//   simpleProp: 'value',
//   objProp: {
//       field1: 'value',
//       field2: 'value'
//   }
// }

const element = ReactSelector('componentName').withProps({
    simpleProp: 'value',
    objProp: {
        field1: 'value',
        field2: 'value'
    }
}, { exactObjectMatch: true })

Note that the partial equality check works for objects of any depth.

// props = {
//     simpleProp: 'value',
//     objProp: {
//         field1: 'value',
//         field2: 'value',
//         nested1: {
//             someField: 'someValue',
//             nested2: {
//                 someField: 'someValue',
//                 nested3: {
//                     field: 'value',
//                     someField: 'someValue'
//                 }
//             }
//         }
//     }
// }


const element = ReactSelector('componentName').withProps({
    simpleProp: 'value',
    objProp: {
        field1: 'value',
        nested1: {
            nested2: {
                nested3: {
                    field: 'value'
                }
            }
        }
    }
}, { exactObjectMatch: false })

Searching for nested components

You can search for a desired subcomponent or DOM element among the component's children using the .findReact(element) method. The method takes the subcomponent name or tag name as a parameter.

Suppose you have the following JSX.

<TodoApp className="todo-app">
    <div>
        <TodoList>
            <TodoItem priority="High">Item 1</TodoItem>
            <TodoItem priority="Low">Item 2</TodoItem>
        </TodoList>
    </div>
</TodoApp>

The following sample demonstrates how to obtain the TodoItem subcomponent.

import { ReactSelector } from 'testcafe-react-selectors';

const component    = ReactSelector('TodoApp');
const div          = component.findReact('div');
const subComponent = div.findReact('TodoItem');

You can call the .findReact method in a chain, for example:

import { ReactSelector } from 'testcafe-react-selectors';

const subComponent = ReactSelector('TodoApp').findReact('div').findReact('TodoItem');

You can also combine .findReact with regular selectors and other) methods like .find or .withText, for example:

import { ReactSelector } from 'testcafe-react-selectors';

const subComponent = ReactSelector('TodoApp').find('div').findReact('TodoItem');

Combining with regular TestCafe selectors

Selectors returned by the ReactSelector constructor are recognized as TestCafe selectors. You can combine them with regular selectors and filter with .withText, .nth, .find and other functions. To search for elements within a component, you can use the following combined approach.

import { ReactSelector } from 'testcafe-react-selectors';

var itemsCount = ReactSelector('TodoApp').find('.items-count span');

Example

Let's use the API described above to add a task to a Todo list and check that the number of items changed.

import { ReactSelector } from 'testcafe-react-selectors';

fixture `TODO list test`
	.page('http://localhost:1337');

test('Add new task', async t => {
    const todoTextInput = ReactSelector('TodoInput');
    const todoItem      = ReactSelector('TodoList TodoItem');

    await t
        .typeText(todoTextInput, 'My Item')
        .pressKey('enter')
        .expect(todoItem.count).eql(3);
});

Obtaining component's props and state

As an alternative to testcafe snapshot properties, you can obtain state, props or key of a ReactJS component.

To obtain component's properties, state and key, use the React selector's .getReact() method.

The .getReact() method returns a client function. This function resolves to an object that contains component's properties (excluding properties of its children), state and key.

const reactComponent      = ReactSelector('MyComponent');
const reactComponentState = await reactComponent.getReact();

// >> reactComponentState
//
// {
//     props:    <component_props>,
//     state:    <component_state>,
//     key:      <component_key>
// }

The returned client function can be passed to assertions activating the Smart Assertion Query mechanism.

Example

import { ReactSelector } from 'testcafe-react-selectors';

fixture `TODO list test`
	.page('http://localhost:1337');

test('Check list item', async t => {
    const el         = ReactSelector('TodoList');
    const component  = await el.getReact();

    await t.expect(component.props.priority).eql('High');
    await t.expect(component.state.isActive).eql(false);
    await t.expect(component.key).eql('componentID');
});

As an alternative, the .getReact() method can take a function that returns the required property, state or key. This function acts as a filter. Its argument is an object returned by .getReact(), i.e. { props: ..., state: ..., key: ...}.

ReactSelector('Component').getReact(({ props, state, key }) => {...})

Example

import { ReactSelector } from 'testcafe-react-selectors';

fixture `TODO list test`
    .page('http://localhost:1337');

test('Check list item', async t => {
    const el = ReactSelector('TodoList');

    await t
        .expect(el.getReact(({ props }) => props.priority)).eql('High')
        .expect(el.getReact(({ state }) => state.isActive)).eql(false)
        .expect(el.getReact(({ key }) => key)).eql('componentID');
});

The .getReact() method can be called for the ReactSelector or the snapshot this selector returns.

TypeScript Generic Selector

Use the generic ReactComponent type to create scalable selectors in TypeScript.

Pass the props object as the type argument to ReactComponent to introduce a type for a specific component.

type TodoItem = ReactComponent<{ id: string }>;

You can then pass the created TodoItem type to the withProps and getReact generic methods.

const component  = ReactSelector('TodoItem');
type TodoItem    = ReactComponent<{ id: string }>;

const item1  = component.withProps<TodoItem>('id', 'tdi-1');
const itemId = component.getReact<TodoItem>(({ props }) => props.id);

Example

import { ReactSelector, ReactComponent } from 'testcafe-react-selectors';

fixture`typescript support`
    .page('http://react-page-example.com')

test('ReactComponent', async t => {
    const todoList         = ReactSelector('TodoList');
    type TodoListComponent = ReactComponent<{ id: string }>;

    const todoListId = todoList.getReact<TodoListComponent>(({ props }) => props.id);

    await t.expect(todoListId).eql('ul-item');
});

Composite Types in Props and State

If a component's props and state include other composite types, you can create your own type definitions for them. Then pass these definitions to ReactComponent as type arguments.

The following example shows custom Props and State type definitions. The State type uses another composite type - Option.

import { ReactComponent } from 'testcafe-react-selectors';

interface Props {
    id: string;
    text: string;
}

interface Option {
    id: number;
    title: string;
    description: string;
}

interface State {
    optionsCount: number;
    options: Option[];
}

export type OptionReactComponent = ReactComponent<Props, State>;

Limitations

• testcafe-react-selectors support ReactJS starting with version 16. To check if a component can be found, use the react-dev-tools extension.

• Search for a component starts from the root React component, so selectors like ReactSelector('body MyComponent') will return null.

• ReactSelectors need class names to select components on the page. Code minification usually does not keep the original class names. So you should either use non-minified code or configure the minificator to keep class names.

  For babel-minify, add the following options to the configuration:

  { keepClassName: true, keepFnName: true }
  

  In UglifyJS, use the following configuration:

  {
      compress: {
          keep_fnames: true
      },
  
      mangle: {
          keep_fnames: true
      }
  }