I developed a React TypeScript application via create-react-app. I have a class called CustomConverter that depends on an external JS library, starting with the following code:
var ExternalModule = function(ExternalModule) {
...
}
I can successfully utilize this library by including it in the index.html file and initializing it with var instance = ExternalModule()
. However, when I attempt to run Jest tests for the CustomConverter class, I encounter a ‘ExternalModule is not defined’ error. What steps should I take to properly integrate this JavaScript library into my testing environment?
To get the external JavaScript library working with Jest for your React TypeScript project, try these steps:
- Install the Library: If the library is available on npm, install it using
npm install library-name
.
- Mock the Library: Create a mock file in the
__mocks__
directory. For example, ExternalModule.js
:
module.exports = jest.fn(() => { /* mock implementation */ });
- Configure Jest: In your
jest.config.js
, make sure to set up moduleNameMapper:
moduleNameMapper: { '^ExternalModule$': '/__mocks__/ExternalModule.js' }
These steps should help Jest recognize and integrate the external library correctly in your tests.