React-Testing-Library - Wrapping Component with Redux and Router

Question

I am trying to setup an test file to render a route/page on my application. I'm trying to wrap everything with Redux and Router, and this is what I have:

import React from 'react';
import { render } from 'react-testing-library';
import { createStore } from 'redux';
import { Provider } from 'react-redux';
import reducer from '../../store/reducer';
import {Link, Route, Router, Switch} from 'react-router-dom'
import {createMemoryHistory} from 'history'

import ViewNode from '../Pages/ViewNode';


const customRender = (
  ui,
  {
    route = '/',
    history = createMemoryHistory({ initialEntries: [route] }),
    initialState,
    store = createStore(reducer, initialState),
    ...options
  } = {}
) => ({
  ...render(
    <Provider store={store}>
      <Router history={history}>{ui}</Router>
    </Provider>,
    options
  ),
  history,
});

test('can render with redux and router', () => {
  const { getByTestId } = customRender(
    <Route path="/server/:env/:nodeName">
      <ViewNode />
    </Route>,
    {
      route: '/server/prod/some.server.name.com',
    }
  );

  expect(getByTestId('page-content')).toBeVisible()
})

Then I get the following error:

Error: Uncaught [TypeError: Cannot read property 'params' of undefined]

The reason this is throwing the error is because it cannot find the React Router params. It's failing in the component constructor when Im initializing the state:

this.state = {
            modal: false,
            activeTab: '1',
            imageStatus: "loading",
            env: props.match.params.env, //failing here
            nodeName: props.match.params.nodeName,
            environments: props.environments,
           }

It seems like it isn't wrapping the router properly with my implementation above.

How would I properly wrap my page component with Redux and Router so that it can get these router params?

Answer 1

You have placed your <ViewNode /> component inside a Route but forgot to pass on the props it receives. That is why props.match is undefined in your component.

You can do this instead:

    <Route path="/server/:env/:nodeName">
      {props => <ViewNode {...props} />}
    </Route>

Basically, you can use one of the 3 ways to render something with a <Route>.

---

Here is a working example:

import React from 'react'
import {Route, Router} from 'react-router-dom'
import {createMemoryHistory} from 'history'
import {render, fireEvent} from '@testing-library/react'
import {createStore} from 'redux'
import {Provider, connect} from 'react-redux'

function reducer(state = {count: 0}, action) {
  switch (action.type) {
    case 'INCREMENT':
      return {
        count: state.count + 1,
      }
    case 'DECREMENT':
      return {
        count: state.count - 1,
      }
    default:
      return state
  }
}

class Counter extends React.Component {
  increment = () => {
    this.props.dispatch({type: 'INCREMENT'})
  }

  decrement = () => {
    this.props.dispatch({type: 'DECREMENT'})
  }

  render() {
    return (
      <div>
        <div data-testid="env-display">{this.props.match.params.env}</div>
        <div data-testid="location-display">{this.props.location.pathname}</div>
        <div>
          <button onClick={this.decrement}>-</button>
          <span data-testid="count-value">{this.props.count}</span>
          <button onClick={this.increment}>+</button>
        </div>
      </div>
    )
  }
}

const ConnectedCounter = connect(state => ({count: state.count}))(Counter)

function customRender(
  ui,
  {
    initialState,
    store = createStore(reducer, initialState),
    route = '/',
    history = createMemoryHistory({initialEntries: [route]}),
  } = {},
) {
  return {
    ...render(
      <Provider store={store}>
        <Router history={history}>{ui}</Router>
      </Provider>,
    ),
    store,
    history,
  }
}

test('can render with redux and router', () => {
  const {getByTestId, getByText} = customRender(
    <Route path="/server/:env/:nodeName">
      {props => <ConnectedCounter {...props} />}
    </Route>,
    {
      route: '/server/prod/some.server.name.com',
    },
  )

  expect(getByTestId('env-display')).toHaveTextContent('prod')

  expect(getByTestId('location-display')).toHaveTextContent(
    '/server/prod/some.server.name.com',
  )

  fireEvent.click(getByText('+'))
  expect(getByTestId('count-value')).toHaveTextContent('1')
})