Testing React-Intl components with Enzyme's mount() and shallow() methods. This is a helper function which wraps the `intl` context around your component tests in an easy and efficient way.

README.md

When using Enzyme and React-Intl you are likely run into the issues when testing components that use some of React-Intl's components or injected formatting functions. These helper functions (mountWithIntl and shallowWithIntl) aim to address some of the below errors:

Uncaught Invariant Violation: [React Intl] Could not find required ``intl`` object. <IntlProvider> needs to exist in the component ancestry.

TypeError: Cannot read property 'getInstance' of null

Error: ReactWrapper::state() can only be called on the root

Checkout this question at StackOverflow for a complete overview of the issues I ran into:

Injecting react-intl object into mounted Enzyme components for testing

CustomComponent-test.js

import { mountWithIntl } from 'helpers/intl-enzyme-test-helper.js';

const wrapper = mountWithIntl(
  <CustomComponent />
);

expect(wrapper.state('foo')).to.equal('bar');    // OK
expect(wrapper.text()).to.equal('Hello World!'); // OK

CustomComponent.js

import React from 'react';
import { FormattedMessage } from 'react-intl';

class CustomComponent extends React.Component {
  state = {
    foo: 'bar'
  }

  render() {
    return (
      <div>
        <FormattedMessage id="world.hello" defaultMessage="Hello World!" />
      </div>
    );
  }
}

intl-enzyme-test-helper.js

/**
 * Components using the react-intl module require access to the intl context.
 * This is not available when mounting single components in Enzyme.
 * These helper functions aim to address that and wrap a valid,
 * English-locale intl context around them.
 */

import React from 'react';
import { IntlProvider, intlShape } from 'react-intl';
import { mount, shallow } from 'enzyme';

// You can pass your messages to the IntlProvider. Optional: remove if unneeded.
const messages = require('../locales/en'); // en.json

// Create the IntlProvider to retrieve context for wrapping around.
const intlProvider = new IntlProvider({ locale: 'en', messages }, {});
const { intl } = intlProvider.getChildContext();

/**
 * When using React-Intl `injectIntl` on components, props.intl is required.
 */
function nodeWithIntlProp(node) {
  return React.cloneElement(node, { intl });
}

/**
 * Export these methods.
 */
export function shallowWithIntl(node) {
  return shallow(nodeWithIntlProp(node), { context: { intl } });
}

export function mountWithIntl(node) {
  return mount(nodeWithIntlProp(node), {
    context: { intl },
    childContextTypes: { intl: intlShape }
  });
}

Similar to @svedova's approach, we just mock up the intl prop on the component, and then shallow-render the unwrapped component itself.
E.g.:

import { MyComp } from './MyComp' // as opposed to the default export

describe...

it('blabla', () => {
  const intl = {
    formatMessage: () => 'translatedText',
  }
  const wrapper = shallow(<MyComp intl={intl} />)
  expect(...
})

Obviously, this assumes you export MyComp as a named export (in addition to a default export of injectIntl(MyComp)), which I think is absolutely fine.

Got it working with @svedova suggestion.

Im having problems with these aproaches when testing redux connected components + intl injected components.

The test is rising this error:

Invariant Violation: Could not find "store" in either the context or props of "Connect(List)". Either wrap the root component in a , or explicitly pass "store" as a prop to "Connect(List)"

code:
const wrapper = shallowWithIntl(<List />, store);
wrapper.dive()

I want to Dive to traverse to my List component to make some assertions.

Changing the locale to german, 'de', in the instantiation of IntlProvider doesn't "load" the translation.

I'm passing a set of german messages with translations, but the IntlProvider just work properly if we pass the locale as 'en'.

Do you know how to handle this? (I'm trying different approachs here, but none of them worked)

@mrcosta I changed the code to the following to pass the locale while mounting my component. This makes it a bit easier for me to test the localized content.

import React from 'react';
import { IntlProvider, intlShape } from 'react-intl';
import { mount, shallow } from 'enzyme';

function nodeWithIntlProp(node, { intl }) {
  return React.cloneElement(node, { intl });
}

export function shallowWithIntl(node, setLocale) {
  const messages = require(`../../locales/${setLocale}-messages`); // locale.json
  const intlProvider = new IntlProvider({ locale: setLocale, messages }, {});
  const { intl } = intlProvider.getChildContext();
  return shallow(nodeWithIntlProp(node, { intl }), {
    context: { intl }
  });
};

export function mountWithIntl(node, setLocale) {
  const messages = require(`../../locales/${setLocale}-messages`); // locale.json
  const intlProvider = new IntlProvider({ locale: setLocale, messages }, {});
  const { intl } = intlProvider.getChildContext();

  return mount(nodeWithIntlProp(node, { intl }), {
    context: { intl },
    childContextTypes: { intl: intlShape }
  });
};

@gurusewak thanks for this solution! Works like a charm!

Try to fix working tests after i18n implementation:

 it('Component renders', () => {
    const wrapper = shallowWithIntl(<Component />)
    expect(wrapper.length).toBe(1)
    expect(wrapper.hasClass('Component')).toBeTruthy()
  })

and have error

TypeError: Cannot read property 'intl' of undefined
 at Object.<anonymous> (helpers\intl-enzyme-test-helper.js

if test without helper
const wrapper = shallow(<AddToRosterResponse />)
get error

expect(received).toBeTruthy()
    Expected value to be truthy, instead received
      false

Can you pls tell what is wrong?

Here's what I'm using in case it is helpful to anyone else:

/**
 * Components using the react-intl module require access to the intl context.
 * This is not available when mounting single components in Enzyme.
 * These helper functions aim to address that and wrap a valid,
 * English-locale intl context around them.
 */

import React from 'react';
import { IntlProvider, intlShape } from 'react-intl';
import { mount, shallow } from 'enzyme';
import localizationHelper, { englishLocalizationFilePath } from '../../app/assets/js/apps/foo/localizationHelper';

// Create the IntlProvider to retrieve context for wrapping around.
const intlProvider = new IntlProvider(
  { locale: 'en', messages: localizationHelper }, {}
);
const { intl } = intlProvider.getChildContext();

/**
 * When using React-Intl `injectIntl` on components, props.intl is required.
 */
function nodeWithIntlProp(node) {
    return React.cloneElement(node, { intl });
}

export function shallowWithIntl(node, { context, ...additionalOptions } = {}) {
    if (node.type.name === 'InjectIntl') {
      const unwrappedType = node.type.WrappedComponent;
      node = React.createElement(unwrappedType, node.props);
    }
    return shallow(
        nodeWithIntlProp(node),
        {
            context: Object.assign({}, context, {intl}),
            ...additionalOptions,
        }
    );
}

export function mountWithIntl(node, { context, childContextTypes, ...additionalOptions } = {}) {
    if (node.type.name === 'InjectIntl') {
      const unwrappedType = node.type.WrappedComponent;
      node = React.createElement(unwrappedType, node.props);
    }
    return mount(
        nodeWithIntlProp(node),
        {
            context: Object.assign({}, context, {intl}),
            childContextTypes: Object.assign({}, { intl: intlShape }, childContextTypes),
            ...additionalOptions,
        }
    );
}

Now I can use mountWithIntl and shallowWithIntl without having to have double exports in my files (one for the wrapped version, one for the unwrapped).

I can simply do:

wrapper = shallowWithIntl(
        <MyComponent
          onSubmit={submitSpy}
          localeData={localeData}
        />
      );

Basically, when a node gets passed in to mountWithIntl, I get the wrapped component and create a new node using that unwrapped component. Then the helper injects intl into props.

My specs can all pretty much stay the same now. The only changes in my specs are:

1 - Change references to mount and shallow to mountWithIntl and shallowWithIntl for components wrapped by injectIntl.
2 - When spying on functions on the prototype, use:

      spy = sinon.spy(Foo.WrappedComponent.prototype, 'handleSubmit');

instead of

      spy = sinon.spy(Foo.prototype, 'handleSubmit');

Hope this helps someone!

rickarubio's method works! Especially when you use @injectIntl on your component.

I try use solution from @gurusewak, but I still have error with intl.

 FAIL  src/modules/Public/Login/__tests__/WelcomeMessage.test.js
  LoginPage WelcomeMessage
    ✕ Should have a welcome text (9ms)

  ● LoginPage WelcomeMessage › Should have a welcome text

    TypeError: Cannot read property 'intl' of undefined

      11 |   const messages = require(`../i18n/locales/${setLocale}.json`); // locale.json
      12 |   const intlProvider = new IntlProvider({ locale: setLocale, messages }, {});
    > 13 |   const { intl } = intlProvider.getChildContext();
         |           ^
      14 |   return shallow(nodeWithIntlProp(node, { intl }), {
      15 |     context: { intl },
      16 |   });

and test:

import React from 'react';
import { shallowWithIntl } from '../../../../helpers/intl-enzyme-test-helper';
import WelcomeMessage from '../Components/WelcomeMessage';

describe('LoginPage WelcomeMessage', () => {
  it('Should have a welcome text', () => {
    const { wrapper } = shallowWithIntl(<WelcomeMessage />, 'en-GB');
    expect(wrapper.find('h1').exists()).toBe(true);
  });
});

Thanks for advice

Thats how I achieve the things:

import React from 'react';
import StandardFilterIntl, {StandardFilter} from 'bundles/components/Filter/StandardFilter';
import {mountWithIntl} from 'enzyme-react-intl';

const FilterComponent = mountWithIntl(<StandardFilterIntl {...standardFilterProps} />);
FilterComponent.find(StandardFilter).state()

@mirague I use your method but cannot render the component properly. Can you help me with this problem?

import React from 'react';
import {injectIntl, IntlProvider} from 'react-intl'

import { mount, shallow } from 'enzyme';
import Enzyme from 'enzyme';
import Adapter from 'enzyme-adapter-react-16';
const defaultLocale = 'en'
const locale = defaultLocale

function mountWithIntl(node) {
  return mount(node, {
    wrappingComponent: IntlProvider,
    wrappingComponentProps: {
      locale,
      defaultLocale,
      messages: {},
    },
  })
}

function shallowWithIntl(node) {
  return shallow(node, {
    wrappingComponent: IntlProvider,
    wrappingComponentProps: {
      locale,
      defaultLocale,
      messages: {},
    },
  })
}

Enzyme.configure({
  adapter: new Adapter()
});

class Func extends React.Component {
  render() {
    return <div>{int.formatMessage({id:'xxx'})}</div>
  }
}

const Component = injectIntl(Func);

describe('Name of the group', () => {
  it('should ', () => {
    const component = shallowWithIntl(<Component/>);
    expect(component.find('div').length).toBe(1);
    console.log(component);
  });
});

`

 FAIL  src/App.test.js
  Name of the group
    × should  (15ms)

  ● Name of the group › should 

    expect(received).toBe(expected) // Object.is equality

    Expected: 1
    Received: 0

      45 |   it('should ', () => {
      46 |     const component = shallowWithIntl(<Component/>);
    > 47 |     expect(component.find('div').length).toBe(1);
         |                                          ^
      48 |     console.log(component);
      49 |   });
      50 | });

      at Object.<anonymous> (src/App.test.js:47:42)

Test Suites: 1 failed, 1 total
Tests:       1 failed, 1 total
Snapshots:   0 total
Time:        4.275s