How does lance-gg know whether to load the client

Question

I am trying to write a unit test for a Renderer subclass from lance-gg

// test/client.js
const lance = require('lance-gg');
console.log(lance);

{
  GameEngine: [Function: GameEngine],
  GameWorld: [Function: GameWorld],
  P2PhysicsEngine: [Function: P2PhysicsEngine],
  SimplePhysicsEngine: [Function: SimplePhysicsEngine],
  BaseTypes: [Function: BaseTypes] {
    TYPES: {
      FLOAT32: 'FLOAT32',
      INT32: 'INT32',
      INT16: 'INT16',
      INT8: 'INT8',
      UINT8: 'UINT8',
      STRING: 'STRING',
      CLASSINSTANCE: 'CLASSINSTANCE',
      LIST: 'LIST'
    }
  },
  TwoVector: [Function: TwoVector],
  DynamicObject: [Function: DynamicObject],
  PhysicalObject2D: [Function: PhysicalObject2D],
  PhysicalObject3D: [Function: PhysicalObject3D],
  ServerEngine: [Function: ServerEngine],
  Lib: { Trace: [Function: Trace] }
}

./node_modules/.bin/mocha --require @babel/register ./test/client.js

However, lance.Renderer resolves to undefined, which leads me to suspect that somehow lance is building from the server exports rather than the client exports defined here: https://github.com/lance-gg/lance/blob/911b60bdb5b887aa281e7c968506028797616132/rollup.config.js

Here is an example of an existing test that seems to compile the client-side code into the test properly: https://github.com/lance-gg/lance/blob/master/test/EndToEnd/multiplayer.js

My question is, how does require('lance-gg') know whether to import the client-side or server-side

How do I get the test to compile from the client-side exports instead?

score 0 · Answer 1 · answered Jan 24 '21 at 09:50

The lance library is common to both client and server, even though it is a single package. The way the differentiation happens between the two possible imports is through the main and browser attributes of lance's package.json file.

Take a look at https://github.com/lance-gg/lance/blob/master/package.json and at those two attributes.

In your case, mocha needs to indicate that it is loading the browser-intended package. It sounds like mocha is fetching the main entry point.

See https://docs.npmjs.com/cli/v6/configuring-npm/package-json#browser

How does lance-gg know whether to load the client

1 Answers1