Unit test does not fail when I change my React component changes - reactjs

Question

My test does not fail when making changes to App.js.
I'm using jest, enzyme, react.js, react-create-app, and react-scripts.
As I update the App.js component, I expect that the test should fail because it does not match the snapshot of App.js. I think it has to do with my _ snapshot _/App.test.js file... How do I fix this? Any ideas?
Here is my code:
src/components/App.js:
import React, { Component } from 'react';
class App extends Component {
render() {
return (
<div>
<h2>Gift Giver</h2>
</div>
);
}
}
export default App;
src/components/App.test.js:
import React from 'react';
import { shallow } from 'enzyme';
import App from './App';
const app = shallow(<App />);
it('renders correctly', () => {
expect(app).toMatchSnapshot();
});
src/components/__ snapshots __/App.test.js.snap
exports[`renders correctly 1`] = `ShallowWrapper {}`;
package.json:
{
"name": "giftgiver",
"version": "0.1.0",
"private": true,
"dependencies": {
"enzyme": "^3.10.0",
"react": "^16.8.6",
"react-bootstrap": "^1.0.0-beta.9",
"react-dom": "^16.8.6",
"react-scripts": "3.0.1",
"react-test-render": "^1.1.1"
},
"scripts": {
"start": "react-scripts start",
"build": "react-scripts build",
"test": "react-scripts test",
"eject": "react-scripts eject"
},
"eslintConfig": {
"extends": "react-app"
},
"browserslist": {
"production": [
">0.2%",
"not dead",
"not op_mini all"
],
"development": [
"last 1 chrome version",
"last 1 firefox version",
"last 1 safari version"
]
},
"devDependencies": {
"enzyme-adapter-react-16": "^1.14.0"
}
}
As I update the App.js component, I expect that the test should fail because it does not match the snapshot of App.js

Answer 1

You have to use .debug() when rendering snapshots.
import React from 'react';
import { shallow } from 'enzyme';
import App from './App';
const app = shallow(<App />);
it('renders correctly', () => {
expect(app.debug()).to.matchSnapshot();
});
As an aside, generally it's better to use mount instead of shallow unless there's a very good reason not to.