Jest (JavaScript framework)

Jest[1] is a JavaScript testing framework maintained by Facebook, Inc. with a focus on simplicity. It works with projects using: Babel, TypeScript, Node.js, React, Angular, Vue.js and Svelte. 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.

gollark: User code presumably knows whether what it has is a UDP socket, TCP socket, or file.
gollark: Are syscall numbers scarce somehow?
gollark: I don't see the value in packing multiple different things into one syscall because the arguments happen to be the same when the kernel will have to check and dispatch to different things *anyway*, and user code also has to use a specific known form anyway.
gollark: Realer programmers make everything based on CHANNELS.- Rob Pike
gollark: yes.

See also

References
  1. "Jest Website".
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