Jest (JavaScript framework)

Jest[1] is a JavaScript Testing Framework with a focus on simplicity. It works with projects using: Babel, TypeScript[2], Node.js, React, Angular and Vue.js. It aims to work out of the box and config free.

Usage and examples

$ npm install --save-dev jest

For the following module, we will write a corresponding test case: 

function sum(a, b) {
  return a + b;
}
module.exports = sum;

If the above file was named sum.js, we will write our test case in a file named sum.test.js for jest to automatically pick it up. The contents of the file will be: 

const sum = require('./sum');

test('adds 1 + 2 to equal 3', () => {
  expect(sum(1, 2)).toBe(3);
});
module.exports = sum;

Then, from the command line, run the command 

$ npm run test

This runs the test and outputs the corresponding result in your command line.

See also

References

  1. ^ "Jest Website".
  2. ^ "How to setup Jest in a TypeScript, Babel and Webpack project". Wisdom Geek. Kataria, Saransh. Retrieved 9 April 2019.

External links