Example of how to test a component that uses useQuery?

Question

I have a React component that uses the Apollo hooks lib's useQuery hook. I'm having trouble testing this component. Here is my current setup.

import React from 'react';
import { BrowserRouter as Router } from 'react-router-dom';
import DashboardBar from './DashboardBar';
import { render, cleanup } from '@testing-library/react';
import { QUERY } from '../../queries';
import { ApolloClient } from 'apollo-client';
import { ApolloProvider as ApolloHooksProvider } from '@apollo/react-hooks';
import { MockedProvider } from 'react-apollo/test-utils';
import { InMemoryCache } from 'apollo-cache-inmemory';
import { MockLink } from 'apollo-link-mock';
import wait from 'waait';
import casual from 'casual';

describe('<DashboardBar />', () => {
  it('renders and matches snapshot', async () => {
    const mocks = [
      {
        request: { query: QUERY, variables: { id: 'WLYhM' } },
        result: {
          data: {
            q: {
              brand: fakeBrand,
              claimByAction: casual.boolean,
              claimRules: fakeClaimRules,
              wantIn: fakeWantIn,
            },
          },
        },
      },
    ];

    function createClient(mocks) {
      return new ApolloClient({
        cache: new InMemoryCache(),
        link: new MockLink(mocks),
      });
    }

    const client = createClient(mocks);

    const { container } = render(
      <ApolloHooksProvider client={client}>
        <Router>
          <DashboardBar {...props} store={reduxStore.store} />
        </Router>
      </ApolloHooksProvider>
    );

    console.log(container.firstChild);
    expect(container.firstChild).toBe(null);

    await wait(200);

    console.log(container.firstChild);
  });
});

When I run the test, I'm getting the following error

TypeError: Cannot read property 'q' of undefined

Even though the data is being returned fine in the actual component.

Does anyone have an example of how the successfully set up and executed tests w/ components using hooks from the Apollo hooks lib?

Thanks!

Answer 1

Actually I managed to get this working using act()

Example as follows:

import { MockedProvider } from '@apollo/react-testing'
import query from 'data/graphql/Device/psaButton.graphql'
import React from 'react'
import { act, create, ReactTestRenderer } from 'react-test-renderer'
import { MockAppNoLayout } from 'testHelpers/testHelpers'
import waitForExpect from 'wait-for-expect'
import PSAButton from './PSAButton'

const mocks = [
  {
    request: {
      query,
      variables: {
        deviceId: '1',
      },
    },
    result: {
      data: {
        deviceById: {
          id: '1',
          info: {
            psaUrl: 'asdsadsad',
            lastSyncDate: 'asdasd',
            lastVerifyDate: 'asdsad',
          },
        },
        user: {
          timeZone: 'Europe/London',
        },
      },
    },
  },
]

describe('PSAButton', () => {
  it('renders correctly', async () => {
    let wrapper: ReactTestRenderer
    act(() => {
      wrapper = create(
        <MockAppNoLayout>
          <MockedProvider mocks={mocks} addTypename={false}>
            <PSAButton deviceId="1" />
          </MockedProvider>
        </MockAppNoLayout>,
      )
    })

    await waitForExpect(() => {
      const testInstance = wrapper.root
      expect(testInstance.findByType('span').children[0]).toBe('Open In PSA')
    })
  })
})

MockAppNoLayout is a React component tree containing amock IntlProvider and Styleprovider and the such like, (not important for this question).