Document how to run async subtests

[mk-pmb]

My naive approach would be something like this but obviously that's not how it works:

$ nodejs -r esm test/naive.mjs
TAP version 13
# Import package meta
# can read
# homepage alive
ok 1 should be equal
# has no bugs
TypeError: Cannot read property 'homepage' of undefined
    at Test.t.test (…

So how do I write async subtests? And can I have the parent test's name prefixed in front of the subtest name?

[RyanZim]

tape-promise currently doesn't have proper support for t.test(), but I'd be in support of adding it. @mk-pmb care to submit a PR?

[mk-pmb]

I probably won't have time for it in weeks, sorry. If I do, of course you'll get a PR. :-)

[ExE-Boss]

This feels to be correct and by design to me, as this won’t work in Jest either:

describe('Import package meta', async () => {
	let meta;

	await test('can read', async () => {
		meta = (await import('../package.json')).default;
		expect(meta && typeof meta).toEqual('object');
	});

	await test('homepage alive', async () => {
		const webRequest = await stubAsyncDataSource(meta.homepage);
		expect(webRequest.httpStatus).toEqual(200);
		expect(webRequest.title).toEqual(meta.name);
	});

	await t.test('has no bugs', async () => {
		const webRequest = await stubAsyncDataSource(meta.bugs.url);
		expect(webRequest.httpStatus).toEqual(200);
		expect(webRequest.meta.nBugs).toEqual(0);
	});
});

You should instead perform the async import of package.json at the top:

test('Import package meta', async (t) => {
	t.plan(3);
	let meta = (await import('../package.json')).default;

	t.test('can read', async (sub) => {
		sub.plan(1);
		sub.equal((meta && typeof meta), 'object');
	});

	t.test('homepage alive', async (sub) => {
		sub.plan(2);
		const webRequest = await stubAsyncDataSource(meta.homepage);
		sub.equal(webRequest.httpStatus, 200);
		sub.equal(webRequest.title, meta.name);
	});

	t.test('has no bugs', async (sub) => {
		sub.plan(2);
		const webRequest = await stubAsyncDataSource(meta.bugs.url);
		sub.equal(webRequest.httpStatus, 200);
		sub.equal(webRequest.meta.nBugs, 0);
	});
});

[mk-pmb]

Then how would I test dynamic imports where the filename is the result of another test reading the output of a shell command?

[ExE-Boss]

As sub‑tests of the test that reads the output.

[mk-pmb]

This feels to be correct and by design to me

Are there any benefits from having the current restrictions, making subtests less capable than top-level tests? Otherwise I'd say let's empower them, independent of what other test frameworks do.

[ExE-Boss]

You can't do this with top‑level tests either.