jest-in-case
Jest utility for creating variations of the same test
Example
import { add, subtract } from './math';
import cases from 'jest-in-case';
cases('add(augend, addend)', opts => {
expect(add(opts.augend, opts.addend)).toBe(opts.total);
}, [
{ name: '1 + 1 = 2', augend: 1, addend: 1, total: 2 },
{ name: '2 + 1 = 3', augend: 2, addend: 1, total: 3 },
{ name: '3 + 1 = 4', augend: 3, addend: 1, total: 4 },
]);Installation
yarn add --dev jest-in-caseUsage
In your Jest tests, import cases from
jest-in-case.
import cases from 'jest-in-case';
// or
const cases = require('jest-in-case');Then you can call cases with a title, a tester, and some testCases.
cases(title, tester, testCases);testCases can either be an array of objects with a name property:
cases('add(augend, addend)', opts => {
expect(add(opts.augend, opts.addend)).toBe(opts.total);
}, [
{ name: '1 + 1 = 2', augend: 1, addend: 1, total: 2 },
{ name: '2 + 1 = 3', augend: 2, addend: 1, total: 3 },
{ name: '3 + 1 = 4', augend: 3, addend: 1, total: 4 },
]);Or an object of objects with the names as the keys:
cases('subtract(minuend, subtrahend)', opts => {
expect(subtract(opts.minuend, opts.subtrahend)).toBe(opts.difference);
}, {
'1 - 1 = 0': { minuend: 1, subtrahend: 1, difference: 0 },
'2 - 1 = 1': { minuend: 2, subtrahend: 1, difference: 1 },
'3 - 1 = 2': { minuend: 3, subtrahend: 1, difference: 2 },
});Inside of a test case you can put whatever properties you want, except for
name, only, or skip:
cases('title', fn, [
{ name: 'reserved 1', only: true, skip: true, whatever: 'you', want: 'here' },
{ name: 'reserved 2', only: true, skip: true, whatever: 'you', want: 'here' },
{ name: 'reserved 3', only: true, skip: true, whatever: 'you', want: 'here' },
]);nameis passed totest(name, fn)to become the name of your test- When
onlyis set totrueit will use Jest'stest.onlyfunction - When
skipis set totrueit will use Jest'stest.skipfunction
The tester function is called on each test case with your options:
cases('title', opts => {
console.log('passed: ', opts);
}, {
'test 1': { foo: 1 },
'test 2': { bar: 2 },
'test 3': { baz: 3 },
});
// passed: { foo: 1 }
// passed: { bar: 2 }
// passed: { baz: 3 }Your tester function works just like functions passed to Jest's test function
do (Just with a prepended argument):
cases('async functions', async opts => {
let result = await somethingAsync(opts.input);
expect(result).toEqual(opts.result);
}, {
'test 1': { ... },
'test 2': { ... },
});
cases('done callback', (opts, done) => {
somethingAsync(opts.input, result => {
expect(result).toEqual(result);
done();
});
}, {
'test 1': { ... },
'test 2': { ... },
});