Having the following component:
import React, { useState, useEffect } from 'react';
import { createPortal } from 'react-dom';
import { useRouteMatch, Link } from 'react-router-dom';
interface MyComponentProps {
myId?: string;
link?: string;
}
export const MyComponent: React.FunctionComponent<MyComponentProps> = ({
myId = 'default-id',
link,
children
}) => {
const [myOutlet, setMyOutlet] = useState<HTMLOListElement>();
const match = useRouteMatch();
useEffect(() => {
const outletElement = document.getElementById(myId) as HTMLOListElement;
if (outletElement) {
setMyOutlet(outletElement);
}
}, [myId]);
if (!myOutlet) {
return null;
}
return createPortal(
<li>
<Link to={link || match.url}>{children}</Link>
</li>,
myOutlet
);
};
export default MyComponent;
I want to write unit tests using React Testing Library for it, the problem is that it keeps throwing an error because of useRouteMatch.
Here is my code:
import { render, screen } from '#testing-library/react';
import { MyComponent } from './my-component';
describe('MyComponent', () => {
const testId = 'default-id';
const link = '/route';
it('should render MyComponent successfully', () => {
const element = render(<MyComponent myId={testId} link={link} />);
expect(element).toBeTruthy();
});
});
The error appears at the line with const match = useRouteMatch();, is there a way to include this part in the test?
You should use <MemoryRouter>:
A <Router> that keeps the history of your “URL” in memory (does not read or write to the address bar)
Provide mock locations in the history stack by using the initialEntries props.
Then, use <Route> component to render some UI when its path matches the current URL.
The following example, assuming that the location pathname in the browser current history stack is /one, <Route>'s path prop is also /one, The two matching, rendering MyComponent.
E.g.
my-component.tsx:
import React, { useState, useEffect } from 'react';
import { createPortal } from 'react-dom';
import { useRouteMatch, Link } from 'react-router-dom';
interface MyComponentProps {
myId?: string;
link?: string;
}
export const MyComponent: React.FunctionComponent<MyComponentProps> = ({ myId = 'default-id', link, children }) => {
const [myOutlet, setMyOutlet] = useState<HTMLOListElement>();
const match = useRouteMatch();
console.log('match: ', match);
useEffect(() => {
const outletElement = document.getElementById(myId) as HTMLOListElement;
if (outletElement) {
setMyOutlet(outletElement);
}
}, [myId]);
if (!myOutlet) {
return null;
}
return createPortal(
<li>
<Link to={link || match.url}>{children}</Link>
</li>,
myOutlet
);
};
export default MyComponent;
my-component.test.tsx:
import React from 'react';
import { render, screen } from '#testing-library/react';
import { MyComponent } from './my-component';
import { MemoryRouter, Route } from 'react-router-dom';
describe('MyComponent', () => {
const testId = 'default-id';
const link = '/route';
it('should render MyComponent successfully', () => {
const element = render(
<MemoryRouter initialEntries={[{ pathname: '/one' }]}>
<Route path="/one">
<MyComponent myId={testId} link={link} />
</Route>
</MemoryRouter>
);
expect(element).toBeTruthy();
});
});
test result:
PASS examples/70077434/my-component.test.tsx (8.433 s)
MyComponent
✓ should render MyComponent successfully (46 ms)
console.log
match: { path: '/one', url: '/one', isExact: true, params: {} }
at MyComponent (examples/70077434/my-component.tsx:13:11)
------------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
------------------|---------|----------|---------|---------|-------------------
All files | 87.5 | 28.57 | 100 | 86.67 |
my-component.tsx | 87.5 | 28.57 | 100 | 86.67 | 18,26
------------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 8.951 s, estimated 9 s
package versions:
"react": "^16.14.0",
"react-router-dom": "^5.2.0"
Related
iam having trouble with covering function inside react context
Before that, let me show you the snippet of the code
import {
useCallback,
useEffect,
useState,
createContext,
ReactNode,
FC
} from 'react';
import { useHistory, useLocation } from 'react-router-dom';
import PropTypes from 'prop-types';
import { pushBackRoute } from '../libs/helpers/backRouteHelper';
export interface BottomBarProviderProps {
children: ReactNode;
}
export interface IBottomBarProvider {
selectedMenu: string;
handleClickMenu: (item: { name: string; route: string }) => void;
}
export const defaultValueBottomBarContext = {
selectedMenu: '',
handleClickMenu: () => {}
};
export const BottomBarContext = createContext<IBottomBarProvider>(
defaultValueBottomBarContext
);
export const BottomBarProvider: FC<BottomBarProviderProps> = ({
children,
...props
}) => {
const history = useHistory();
const location = useLocation();
const [selectedMenu, setSelectedMenu] = useState('Belanja');
const handleClickMenu = useCallback(
(item) => {
setSelectedMenu(item.name);
pushBackRoute(location.pathname);
history.push(item.route);
},
[selectedMenu, location?.pathname]
);
useEffect(() => {
Iif (location.pathname === '/marketplace/history') {
setSelectedMenu('Riwayat');
}
}, [location.pathname]);
const value: IBottomBarProvider = {
selectedMenu,
handleClickMenu
};
return (
<BottomBarContext.Provider
value={value}
{...props}
data-testid="bottom-bar-context"
>
{children}
</BottomBarContext.Provider>
);
};
BottomBarProvider.propTypes = {
children: PropTypes.node
};
BottomBarProvider.defaultProps = {
children: null
};
So i managed to cover most of the hooks and render, but the function/handle function inside this context is really hard
And this is my current test code, below :
/* eslint-disable jest/prefer-called-with */
import { render, screen } from '#testing-library/react';
import { BottomBarProvider } from './BottomBarContext';
import '#testing-library/jest-dom/extend-expect';
const mockHistoryPush = jest.fn();
jest.mock('react-router-dom', () => ({
...jest.requireActual('react-router-dom'),
useLocation: () => ({
pathname: '/marketplace'
}),
useHistory: () => ({
push: mockHistoryPush
})
}));
describe('BottomBarProvider', () => {
it('should render the children and update the selected menu when handleClickMenu is called', () => {
//Arrange
const children = <div data-testid="children">Hello, World!</div>;
//Act
render(<BottomBarProvider>{children}</BottomBarProvider>);
//Assert
expect(screen.getByTestId('children')).toHaveTextContent('Hello, World!');
});
});
Do you guys have any idea how to cover the function inside this context ?
Mock functions, hooks, and components of the module you don't own are not recommended. The useLocation and useHistory hooks in your case. Incorrect mock will break their functions which causes your tests to pass based on incorrect mock implementation.
Use <MemoryRouter/> component for testing history change. See official example of RTL about how to test react router
You should also create a test component to consume the React Context for testing the <BottomBarProvider/> component and BottomBarContext. The key is to trigger the handleClickMenu event handler by firing a click event on some element of the test component.
E.g.
BottomBarContext.tsx:
import React from 'react';
import {
useCallback,
useEffect,
useState,
createContext,
ReactNode,
FC
} from 'react';
import { useHistory, useLocation } from 'react-router-dom';
// import { pushBackRoute } from '../libs/helpers/backRouteHelper';
export interface BottomBarProviderProps {
children: ReactNode;
}
export interface IBottomBarProvider {
selectedMenu: string;
handleClickMenu: (item: { name: string; route: string }) => void;
}
export const defaultValueBottomBarContext = {
selectedMenu: '',
handleClickMenu: () => { }
};
export const BottomBarContext = createContext<IBottomBarProvider>(
defaultValueBottomBarContext
);
export const BottomBarProvider: FC<BottomBarProviderProps> = ({
children,
...props
}) => {
const history = useHistory();
const location = useLocation();
const [selectedMenu, setSelectedMenu] = useState('Belanja');
const handleClickMenu = useCallback(
(item) => {
setSelectedMenu(item.name);
// pushBackRoute(location.pathname);
history.push(item.route);
},
[selectedMenu, location?.pathname]
);
useEffect(() => {
if (location.pathname === '/marketplace/history') {
setSelectedMenu('Riwayat');
}
}, [location.pathname]);
const value: IBottomBarProvider = {
selectedMenu,
handleClickMenu
};
return (
<BottomBarContext.Provider value={value} {...props} data-testid="bottom-bar-context">
{children}
</BottomBarContext.Provider>
);
};
BottomBarContext.test.tsx:
import { fireEvent, render, screen } from '#testing-library/react';
import '#testing-library/jest-dom';
import React, { useContext } from 'react';
import { MemoryRouter, Route, Switch } from 'react-router-dom';
import { BottomBarContext, BottomBarProvider } from './BottomBarContext';
describe('BottomBarProvider', () => {
test('should pass', async () => {
const TestComp = () => {
const bottomBarContext = useContext(BottomBarContext);
const menuItems = [
{ name: 'a', route: '/a' },
{ name: 'b', route: '/b' },
];
return (
<>
<ul>
{menuItems.map((item) => (
<li key={item.route} onClick={() => bottomBarContext.handleClickMenu(item)}>
{item.name}
</li>
))}
</ul>
<p>selected menu: {bottomBarContext.selectedMenu}</p>
<Switch>
{menuItems.map((item) => (
<Route key={item.route} path={item.route} component={() => <div>{item.name} component</div>} />
))}
</Switch>
</>
);
};
render(
<MemoryRouter initialEntries={['/']}>
<BottomBarProvider>
<TestComp />
</BottomBarProvider>
</MemoryRouter>
);
const firstListItem = screen.getAllByRole('listitem')[0];
fireEvent.click(firstListItem);
expect(screen.getByText('selected menu: a')).toBeInTheDocument();
expect(screen.getByText('a component')).toBeInTheDocument();
});
});
Test result:
PASS stackoverflow/74931928/BottomBarContext.test.tsx (16.574 s)
BottomBarProvider
✓ should pass (116 ms)
----------------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
----------------------|---------|----------|---------|---------|-------------------
All files | 95 | 66.67 | 75 | 94.74 |
BottomBarContext.tsx | 95 | 66.67 | 75 | 94.74 | 50
----------------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 18.184 s, estimated 23 s
Coverage HTML reporter:
I'm new to testing with jest and I want to test the following code.
import React from "react";
import "./ButtonLogin.css";
import { Link } from 'react-router-dom';
function ButtonLogin() {
return (
<Link to="/login"> <button className="button-login">Iniciar sesión</button></Link>
)
}
export default ButtonLogin;
import { MemoryRouter } from 'react-router-dom';
import { render, fireEvent, Link } from '#testing-library/react';
import { ButtonLogin } from './ButtonLogin';
it('routes to a new route', async () => {
ButtonLogin = jest.fn();
const { getByText } = render(
<MemoryRouter ButtonLogin={ButtonLogin}>
<Link to="/login">Iniciar sesión</Link>
</MemoryRouter>
);
fireEvent.click(getByText('Iniciar sesión'));
expect(ButtonLogin).toHaveBeenCalledWith('/login');
});
I have performed the following test but it fails and I get the following error in line 9.
routes to a new route
"ButtonLogin" is read-only.
You can use the createMemoryHistory function and Router component to test it. Create a memory history with initial entries to simulate the current location, this way we don't rely on the real browser environment. After firing the click event, assert the pathname is changed correctly or not.
ButtonLogin.tsx:
import React from 'react';
import { Link } from 'react-router-dom';
function ButtonLogin() {
return (
<Link to="/login">
<button className="button-login">Iniciar sesión</button>
</Link>
);
}
export default ButtonLogin;
ButtonLogin.test.tsx:
import { fireEvent, render } from '#testing-library/react';
import React from 'react';
import { Router } from 'react-router-dom';
import ButtonLogin from './ButtonLogin';
import { createMemoryHistory } from 'history';
describe('ButtonLogin', () => {
test('should pass', () => {
const history = createMemoryHistory({ initialEntries: ['/home'] });
const { getByText } = render(
<Router history={history}>
<ButtonLogin />
</Router>
);
expect(history.location.pathname).toBe('/home');
fireEvent.click(getByText('Iniciar sesión'));
expect(history.location.pathname).toBe('/login');
});
});
test result:
PASS examples/69878146/ButtonLogin.test.tsx (10.675 s)
ButtonLogin
✓ should pass (41 ms)
-----------------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
-----------------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
ButtonLogin.tsx | 100 | 100 | 100 | 100 |
-----------------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 11.722 s, estimated 12 s
package version: "react-router-dom": "^5.2.0"
I'm using NextJS and I'm trying to test the ClientPortal component. I'm using Jest and React Testing Library for testing.
Here's the ClientPortal component:
import { useEffect, useRef, useState } from "react";
import { createPortal } from "react-dom";
export default function ClientPortal({ children, selector }) {
const ref = useRef();
const [mounted, setMounted] = useState(false);
useEffect(() => {
ref.current = document.querySelector(selector);
setMounted(true);
}, [selector]);
return mounted ? createPortal(children, ref.current) : null;
}
How can this be tested using Jest?
First, make sure the testEnvironment configuration is jsdom. For jestjs v26, it's jsdom by default. For jestjs v27, follow this guide to setup the testEnvironment configuration.
The test method is very straightforward. Create a DOM container to store the portal. Query the DOM element and assert whether it exists.
index.jsx:
import { useEffect, useRef, useState } from 'react';
import { createPortal } from 'react-dom';
export default function ClientPortal({ children, selector }) {
const ref = useRef();
const [mounted, setMounted] = useState(false);
useEffect(() => {
ref.current = document.querySelector(selector);
setMounted(true);
}, [selector]);
return mounted ? createPortal(children, ref.current) : null;
}
index.test.jsx:
import React from 'react';
import { render, screen } from '#testing-library/react';
import '#testing-library/jest-dom/extend-expect';
import ClientPortal from './';
function TestChild() {
return <div>child</div>;
}
describe('69550058', () => {
test('should pass', () => {
const main = document.createElement('main');
const portalContainer = document.createElement('div');
portalContainer.id = 'portal-container';
document.body.appendChild(portalContainer);
const { container } = render(
<ClientPortal selector={'#portal-container'}>
<TestChild />
</ClientPortal>,
{ container: document.body.appendChild(main) }
);
expect(screen.getByText(/child/)).toBeInTheDocument();
expect(portalContainer.innerHTML).toEqual('<div>child</div>');
expect(container).toMatchInlineSnapshot(`<main />`);
});
});
test result:
PASS examples/69550058/index.test.jsx (8.941 s)
69550058
✓ should pass (33 ms)
-----------|---------|----------|---------|---------|-------------------
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s
-----------|---------|----------|---------|---------|-------------------
All files | 100 | 100 | 100 | 100 |
index.jsx | 100 | 100 | 100 | 100 |
-----------|---------|----------|---------|---------|-------------------
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 1 passed, 1 total
Time: 9.624 s, estimated 11 s
package versions:
"jest": "^26.6.3",
"react": "^16.14.0",
"react-dom": "^16.14.0",
"#testing-library/react": "^11.2.2",
I have the following a.jsx file which I am trying to test:
import React, { Component } from "react";
import { SideNavigation } from "#xxx/react-components-xxx";
import { withTranslation } from "react-i18next";
class Navigation extends Component {
constructor(props) {
super(props);
}
render() {
const { t } = this.props;
const ITEMS = [
{
type: "section",
text: t("navigation.abc"),
items: [
{
type: "link",
text: t("navigation.abc"),
href: "#/abc"
},
{ type: "link", text: t("navigation.def"), href: "#/def" }
]
}
];
const HEADER = {
href: "#/",
text: t("navigation.title")
};
return (
<SideNavigation
header={HEADER}
items={ITEMS}
/>
);
}
}
export default withTranslation()(Navigation);
And following is the test case I have written:
import React from "react";
import { shallow } from 'enzyme';
import Navigation from '../src/a';
import { SideNavigation } from '#xxx/react-components-xxx';
describe('Navigation component', () => {
it('should render consistently', () => {
const wrapper = shallow(
<Navigation />
);
console.log(wrapper.render());
expect(wrapper).not.toBeNull();
const sideNav = wrapper.find(SideNavigation);
console.log(sideNav.render());
const sideNavProps = sideNav.props();
console.log(sideNavProps);
});
});
And with this, I get following eror:
Method “type” is meant to be run on 1 node. 0 found instead.
14 |
15 | const sideNav = wrapper.find(SideNavigation);
> 16 | console.log(sideNav.render());
| ^
17 | const sideNavProps = sideNav.props();
18 | console.log(sideNavProps);
19 | });
at ShallowWrapper.single (node_modules/enzyme/src/ShallowWrapper.js:1636:13)
at ShallowWrapper.type (node_modules/enzyme/src/ShallowWrapper.js:1372:17)
at ShallowWrapper.render (node_modules/enzyme/src/ShallowWrapper.js:1106:17)
at Object.<anonymous> (tst/components/Navigation.test.js:16:29)
But if I use mount instead of shallow, everything works fine here. Can someone tell what is the issue here?
It's because of the WithTranslation.
They mention it in their doc
For testing purpose of your component you should export the pure component without extending with the withTranslation hoc and test that:
export MyComponent;
export default withTranslation('ns')(MyComponent);
In the test, test the myComponent export passing a t function mock:
import { MyComponent } from './myComponent';
<MyComponent t={key => key} />
So I was trying to create a unit test using jest in ReactJS. The Unit test itself just to verify if the function (from action) has been called
I already tried to mock the function, but the result tells that I must mock the function
Here the code of the function that I want to create a unit test
import { testfunction } from '../../actions/auth';
handleSubmit(userParams) {
this.setState({ form: { ...this.state.form, isFetching: true } });
this.props.dispatch(testfunction(userParams,
this.successCallback.bind(this), this.errorCallback.bind(this)));
}
and for the unit test
import React from 'react';
import { shallow } from 'enzyme';
import toJson from 'enzyme-to-json';
import thunk from 'redux-thunk';
import configureStore from 'redux-mock-store';
import Login from '../../../components/auth/Login';
const mockStore = configureStore([thunk]);
const initialState = {
history: { },
};
const store = mockStore(initialState);
let wrapper;
let history;
let testfunction;
beforeEach(() => {
testfunction= jest.fn();
history = { push: jest.fn() };
wrapper = shallow(
<Login
history={history}
store={store}
testfunction={testfunction}
/>
);
});
describe('handleSubmit()', () => {
test('should call testfunction props', () => {
const component = wrapper.dive();
const instance = component.instance();
const sampleUserParams = {
email: 'test#test.com',
password: 'samplePassword123',
};
instance.handleSubmit(sampleUserParams);
expect(testfunction).toHaveBeenCalled();
});
});
I just want to check if the "testfunction" is called when I called handleSubmit function. But the error message is:
"Expected mock function to have been called."
it feels my way to mock the function is wrong. Does anyone know how to correct way to test that function?
Here is the solution:
index.tsx:
import React, { Component } from 'react';
import { testfunction } from './testfunction';
class Login extends Component<any, any> {
constructor(props) {
super(props);
this.state = {
form: {}
};
}
public render() {
const userParams = {};
return (
<div className="login">
<form onSubmit={() => this.handleSubmit(userParams)}>some form</form>
</div>
);
}
private handleSubmit(userParams) {
this.setState({ form: { ...this.state.form, isFetching: true } });
this.props.dispatch(testfunction(userParams, this.successCallback.bind(this), this.errorCallback.bind(this)));
}
private successCallback() {
console.log('successCallback');
}
private errorCallback() {
console.log('errorCallback');
}
}
export { Login };
testFunction.ts:
async function testfunction(userParams, successCallback, errorCallback) {
return {
type: 'ACTION_TYPE',
payload: {}
};
}
export { testfunction };
Unit test:
import React from 'react';
import { shallow } from 'enzyme';
import { Login } from './';
import { testfunction } from './testfunction';
jest.mock('./testfunction.ts');
describe('Login', () => {
const dispatch = jest.fn();
const sampleUserParams = {
email: 'test#test.com',
password: 'samplePassword123'
};
it('handleSubmit', () => {
const wrapper = shallow(<Login dispatch={dispatch} />);
expect(wrapper.is('.login')).toBeTruthy();
expect(wrapper.find('form')).toHaveLength(1);
wrapper.find('form').simulate('submit');
const cmpInstance = wrapper.instance();
expect(dispatch).toBeCalledWith(
// tslint:disable-next-line: no-string-literal
testfunction(sampleUserParams, cmpInstance['successCallback'], cmpInstance['errorCallback'])
);
// tslint:disable-next-line: no-string-literal
expect(testfunction).toBeCalledWith(sampleUserParams, cmpInstance['successCallback'], cmpInstance['errorCallback']);
});
});
Unit test with coverage report:
PASS src/stackoverflow/57847401/index.spec.tsx
Login
✓ handleSubmit (22ms)
-----------------|----------|----------|----------|----------|-------------------|
File | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s |
-----------------|----------|----------|----------|----------|-------------------|
All files | 86.36 | 100 | 62.5 | 85 | |
index.tsx | 90 | 100 | 71.43 | 88.89 | 27,30 |
testfunction.ts | 50 | 100 | 0 | 50 | 2 |
-----------------|----------|----------|----------|----------|-------------------|
Test Suites: 1 passed, 1 total
Tests: 1 passed, 1 total
Snapshots: 0 total
Time: 3.201s, estimated 4s
Here is the completed demo: https://github.com/mrdulin/jest-codelab/tree/master/src/stackoverflow/57847401