How to test a React component with RouteComponentProps?

Question

I have a component that has props which extend RouteComponentProps that looks like this:

export interface RouteComponentProps<P> {
  match: match<P>;
  location: H.Location;
  history: H.History;
  staticContext?: any;
}

Now, when I use my component in the app, I pass these props to it:

<MyComponent
    match={this.props.match}
    location={this.props.location}
    history={this.props.history}
/>

The props are available already because it's running inside react router.

Now, how do I test this component without match, location, history available?

Do I need to mock them or is it supposed to somehow automatically load them with some helper function?

Solution 1

To answer your last question, the recommended approach is to use <MemoryRouter>< *your component here* ></MemoryRouter> in your tests. Typescript does not pick up that this component will pass the required props to your component, as such I assume it not to be a type safe approach.

This is for React Router v4 and doesn't apply to previous versions.

For a typesafe method to test components that are wrapped with the HOC withRouter you can build the location, history and match from the react-router and history packages.

This example uses enzyme and snapshot testing but could just as easily be any other test.

This avoided me needing to use <MemoryRouter> as a wrapper that typescript did not like anyhow.

// Other imports here
import { createMemoryHistory, createLocation } from 'history';
import { match } from 'react-router';

const history = createMemoryHistory();
const path = `/route/:id`;

const match: match<{ id: string }> = {
    isExact: false,
    path,
    url: path.replace(':id', '1'),
    params: { id: "1" }
};

const location = createLocation(match.url);

test('shallow render', () => {
    const wrapper = shallow(
        <MyComponent history={history}
                     location={location}
                     match={match} />
    );

    expect(wrapper).toMatchSnapshot();
});

CAUTION Do not use this to test implementation detail, it can be tempting but it will cause you a lot of pain should you want to refactor.

Making a helper for this would probably be the best way to make this re-usable.

import { createLocation, createMemoryHistory } from 'history';
import { match as routerMatch } from 'react-router';

type MatchParameter<Params> = { [K in keyof Params]?: string };

export const routerTestProps = <Params extends MatchParameter<Params> = {}>
    (path: string, params: Params, extendMatch: Partial<routerMatch<any>> = {}) => {
        const match: routerMatch<Params> = Object.assign({}, {
            isExact: false,
            path,
            url: generateUrl(path, params),
            params
        }, extendMatch);
        const history = createMemoryHistory();
        const location = createLocation(match.url);

        return { history, location, match };
    };


const generateUrl = <Params extends MatchParameter<Params>>
    (path: string, params: Params): string => {
        let tempPath = path;

        for (const param in params) {
            if (params.hasOwnProperty(param)) {
                const value = params[param];
                tempPath = tempPath.replace(
                    `:${param}`, value as NonNullable<typeof value>
                );
            }
        }

        return tempPath;
    };

Now we can just use the routerTestProps function in our tests

const { history, location, match } = routerTestProps('/route/:id', { id: '1' });

Solution 2

A gentleman by the name of Timmy Huang provided a solution that involves a simple mock...

https://spectrum.chat/react/help/how-do-you-test-components-that-use-routecomponentprops~495fe95b-6925-4e7f-bfe8-65a737c5d24e?m=MTU4Mjk1MjQ4ODQ0MA==

const routeComponentPropsMock = {
  history: {} as any,
  location: {} as any,
  match: {} as any,
}

I tried this using Jest and it worked. My component had this signature...

export const MyComponent: React.FC<RouteComponentProps> = ({location}:RouteComponentProps) => {

My basic test to confirm the component loads then looked like this...

function renderMyComponent() {
  return render(
    <MyComponent {...routeComponentPropsMock}/>
  );
}

Solution 3

I have been looking for a good solution to this. I was hoping I could do it in the mapStateToProps function or something simular, but have not been able to do this yet.

The best I could do was mock this out and pass in the match, location and history. I used the following:

import { RouteComponentProps } from 'react-router'
import { match } from 'react-router-dom';
import {UnregisterCallback, Href} from 'history'

export function getMockRouterProps<P>(data: P) {

    var location: {
            hash: "",
            key: "",
            pathname: "",
            search: "",
            state: {}
        };

    var props: RouteComponentProps<P> = {
    match: {
            isExact: true,
            params: data,
            path: "",
            url: ""
        },
        location: location,
        history: {
            length:2,
            action:"POP",
            location: location,
            push: () => {},
            replace: () => {},
            go: (num) => {},
            goBack: () => {},
            goForward: () => {},
            block: (t) => {
                var temp: UnregisterCallback = null;
                return temp;
            },
            createHref: (t) => {
                var temp: Href = "";
                return temp;
            },
            listen: (t) => {
                var temp: UnregisterCallback = null;
                return temp;
            }

        },
        staticContext: {
        }
    };


    return props;
}

Then in my test I did:

    var routerProps = getMockRouterProps<ReduxTestComponentProps>(null);

    const wrapper = mount<ReduxTestComponent, ReduxTestComponentState>(
            <ReduxTestComponent
                history={routerProps.history}
                location={routerProps.location}
                match={routerProps.match}
                isLoadingTodo={false}
                todos={todos}
                addAsyncTodoActionDispatch={() => mockTodoAddDispatch()}
                deleteTodoActionDispatch={() => mockTodoDeleteDispatch()}
                />
      );