Migrate form Tape to Tap (Run Tests in PARALLEL!) ?

[nelsonic]

Why?

It recently came to our attention in: dwyl/aws-sdk-mock#144

that tap has a couple of really useful features that tape (our current test runner) does not.

We use tape virtually everywhere in our Node.js projects (hence this tutorial)
And in general it works really well for us.
e.g: https://travis-ci.org/dwyl/hapi-auth-jwt2/jobs/376314561

The npm test stage take "only" 5.25 seconds to complete,
which means is't never been a "problem" for us ...

However on bigger Node.js project(s) with many tests e.g: https://github.com/TheScienceMuseum/collectionsonline
https://travis-ci.org/TheScienceMuseum/collectionsonline/builds/409777564#L576

There could be a pretty significant benefit to running tests in Parallel.

What?

• Good intro: https://www.node-tap.org/basics
• t.spawn to run a particularly slow test in a new process: https://www.node-tap.org/advanced
• Parallel: https://www.node-tap.org/parallel

How?

The steps are pretty simple as outlined in:
https://github.com/dwyl/aws-sdk-mock/pull/144/files#diff-0fd0e07cf6d02bf7cf00f18cebb8e6eaR1

We could also include a mini-guide at the end for "how to migrate from Tape to Tap" based on our experience of doing it for a sample project
e.g: https://www.npmjs.com/package/hapi-auth-jwt2 or https://www.npmjs.com/package/decache
both of which can use a devDependencies update ... 🙄

Todo:

• review https://github.com/tapjs/node-tap
• Write-up the reasoning why someone should consider using Tap over Tape.
• Extend the example to cover Tap.
• Migrate "TodoMVC Vanilla" to use Tap.
• Profit!.

[nelsonic]

One of the most useful/important features that Tap has which Tape does not
is t.beforeEach(function (done) {}) and t.afterEach(function (done) {})
see: https://www.node-tap.org/api/

in a recent example I've been working on: https://github.com/dwyl/learn-elm-architecture-in-javascript
The "reset" code takes up 6% of the file and has been the cause of frustration!!
/test/todo-app.test.js#L667-L668

  elmish.empty(document.getElementById(id));
  localStorage.removeItem('todos-elmish_' + id);

e.g:

Simply moving to Tap will mean that we have a single t.afterEach to reset the state,
so that we can have simpler tests that always work and are easier to read/maintain.

[nelsonic]

Proposed Analogy: Single Speed Bike vs. Specialized Racer (With Gears)

Which one would you say is Tape and which is Tap (so we can test the analogy...)

[nelsonic]

Perhaps the best "feature" of Tap is Code Coverage integration!
https://www.node-tap.org/coverage

[nelsonic]

I'm applying a P2 label to this story because I need to use Tap for https://github.com/dwyl/atm
which is a priority for CS, Home and the dwyl website.

[nelsonic]

[nelsonic]

Reduced image size by 70% to respect people on lower bandwidth:

Effect is the same when viewed on GitHub. #LittleThings 😉

[nelsonic]

In the end I decided to simply extend the learn-tape tutorial to cover Tap
and explain the reasoning why someone would want to use Tap instead of Tape with a clear use-case example. ✅

[nelsonic]

closing. see: https://github.com/dwyl/learn-tape/blob/master/tap-advanced-testing.md