Tests: Suggestion, Introduce -webonly keyword to QUnit.module name for skipping the tests on Node.js

[takahirox]

Related issue: #20795 (comment)

Background:

There are two ways to run our unit tests.

1. Run the tests on Node.js with npm run test-unit (or other) command.
2. Run the tests in web browser on http://localhost:8080/test/unit/UnitTests.html.

Problem:

The both run the same unit test sets. (I focus on core source code unit tests for now.) And Three.js partly has code including features Node.js doesn't natively support, for example DOM operation.

Then currently we can't add test cases using such features because the tests fail or terminate on Node.js.

Suggestion:

I'd like to suggest -webonly keyword (better name idea is welcome) to QUnit.module name for skipping such the tests on Node.js.

QUnit.config.filter can filter the tests. My idea is running the tests on Node.js excepts for the ones whose module name includes -webonly while running all the tests on Web.

https://api.qunitjs.com/config/QUnit.config/

Example:

export default QUnit.module( 'Foo', () => {
  QUnit.module('Bar', () => {
    QUnit.test('baz', ( assert ) => {
      // This test runs on both Node.js and Web.
    });
  });
  QUnit.module('Bar-webonly', () => {
    QUnit.test('baz', ( assert ) => {
      // This test runs only on Web.
    });
  });
});

I added WebGLRenderer instantiation test as an example in this PR. new WebGLRenderer() doesn't work as is on Node.js because it has a dependency with document.

The following two screenshots show that the tests pass on both Node.js and Web although the WebGLRenderer() instantiation test is added.

Benefits

We can add the tests more to the unit tests. It helps keeping Three.js functionality.

Alternative solutions

1. Separating the unit tests which don't run on Node.js from the current unit test files. And Node.js runs the separated one while Web test runs the both.
2. Import polyfill or libraries which emulates the features Node.js natively doesn't support for the tests. For example headless-gl for WebGL.

Probably my idea is simpler than the alternatives. Disadvantage compared to 2 is we still can't run the tests using the features Node.js doesn't natively support on Node.js

This contribution is made at San Francisco International Airport.

[Mugen87]

I like this approach since it's an easy solution for enabling more unit tests.

And if we come up with an alternative in the future which allows unit tests to run in the browser and node, it should be no deal to remove -webonly.

[mrdoob]

Thanks!