Ava: Recipe for using a plain function instead of `beforeEach` hook

[sindresorhus]

In many cases you could just use a plain function instead of a beforeEach hook. In the below case it's both more clear and less code.

import test from 'ava';

const setup = () => {
    doStuff();

    return {
        unicorn: fn('unicorn')
        rainbow: fn('rainbow')
    };
}

test('foo', t => {
    const {unicorn, rainbow} = setup();
    t.true(unicorn('foo'));
    t.true(rainbow('foo'));
});

test('bar', t => {
    const {unicorn, rainbow} = setup();
    t.true(unicorn('bar'));
    t.true(rainbow('bar'));
});

With beforeEach it would be:

import test from 'ava';

test.beforeEach(t => {
    doStuff();

    t.context = {
        unicorn: fn('unicorn')
        rainbow: fn('rainbow')
    };
}

test('foo', t => {
    const {unicorn, rainbow} = t.context;
    t.true(unicorn('foo'));
    t.true(rainbow('foo'));
});

test('bar', t => {
    const {unicorn, rainbow} = t.context;
    t.true(unicorn('bar'));
    t.true(rainbow('bar'));
});

Still, there are benefits of beforeEach too. They're not mutually exclusive. beforeEach has benefits like supporting non-promise asynchronicity. Better output when a hook fails. Void hook usage doesn't require a call in each test. And more.

[jamestalmage]

The real advantage of the setup function approach is that you could have more than one, and call them based on what you need in a particular test. (If you interact with the file system, perhaps you run a few tests using mock-fs, and then a few that use the real file system and a temp dir or something).

There is a (very small) performance benefit to not having any beforeEach or afterEach tests. It's not worth worrying about unless you are dealing with hundreds (maybe even thousands) of tests in a single file though.

I have come to prefer the setup() approach personally. It does not require others to be familiar with AVA's t.context, there is no magic.

[JasonRitchie]

Can I pick this up?

[sindresorhus]

@JasonRitchie Of course. Go ahead :)