Enzyme expects an adapter to be configured
Add it to your test case file.
import React from 'react';
import Adapter from 'enzyme-adapter-react-16';
import { shallow, configure } from 'enzyme';
configure({adapter: new Adapter()});
test('message box', ()=> {
...
})
The file 'setupTests' has to be imported to the test file:
import MessageBox from "../MessageBox";
import { shallow } from 'enzyme';
import React from 'react';
import "../setupTests"
test('message box', ()=> {
...
})
Also, if you don't want to import your setupTests.js file into every test file, you can place it in your package.json folder:
"jest": {
"setupTestFrameworkScriptFile": "./test/setupTests.js" }
Update:
Note: setupTestFrameworkScriptFile is deprecated in favor of setupFilesAfterEnv.
https://jestjs.io/docs/en/configuration