avocado/packages/ecs/test/ecs.js

import {expect} from 'chai';

import Bundle from '../src/bundle';
import Ecs from '../src/ecs';
import System from '../src/system';

const Empty = {};

const Position = {
  x: {type: 'int32', defaultValue: 32},
  y: 'int32',
  z: 'int32',
};

it('can add and remove systems at runtime', () => {
  const ecs = new Ecs();
  let oneCount = 0;
  let twoCount = 0;
  const oneSystem = () => {
    oneCount++;
  };
  ecs.addSystem(oneSystem);
  ecs.tick();
  expect(oneCount)
    .to.equal(1);
  const twoSystem = () => {
    twoCount++;
  };
  ecs.addSystem(twoSystem);
  ecs.tick();
  expect(oneCount)
    .to.equal(2);
  expect(twoCount)
    .to.equal(1);
  ecs.removeSystem(oneSystem);
  ecs.tick();
  expect(oneCount)
    .to.equal(2);
  expect(twoCount)
    .to.equal(2);
});

it('can create entities with components', () => {
  const ecs = new Ecs({Empty, Position});
  const entity = ecs.create({Empty: {}, Position: {y: 420}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {x: 32, y: 420, z: 0}}));
});

it("can remove entities' components", () => {
  const ecs = new Ecs({Empty, Position});
  const entity = ecs.create({Empty: {}, Position: {y: 420}});
  ecs.remove(entity, ['Position']);
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}}));
});

it('can get entities unsafely', () => {
  const ecs = new Ecs({Empty, Position});
  const entity = ecs.create({Empty: {}, Position: {y: 420}});
  expect(JSON.stringify(ecs.getUnsafe(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {x: 32, y: 420, z: 0}}));
});

it('can insert components into entities', () => {
  const ecs = new Ecs({Empty, Position});
  const entity = ecs.create({Empty: {}});
  ecs.insert(entity, {Position: {y: 420}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {x: 32, y: 420, z: 0}}));
  ecs.insert(entity, {Position: {y: 69}});
  expect(JSON.stringify(ecs.get(entity)))
    .to.deep.equal(JSON.stringify({Empty: {}, Position: {x: 32, y: 69, z: 0}}));
});

it('can tick systems', () => {
  const Momentum = {
    x: 'int32',
    y: 'int32',
    z: 'int32',
  };
  const ecs = new Ecs({Momentum, Position});
  class Physics extends System {

    static queries() {
      return {
        default: ['Position', 'Momentum'],
      };
    }

    tick(elapsed) {
      expect(elapsed)
        .to.equal(1);
      // eslint-disable-next-line no-restricted-syntax
      for (const [position, momentum] of this.select('default')) {
        position.x += momentum.x * elapsed;
        position.y += momentum.y * elapsed;
        position.z += momentum.z * elapsed;
      }
    }

  }
  ecs.addSystem(Physics);
  const entity = ecs.create({Momentum: {}, Position: {y: 420}});
  const position = JSON.stringify(ecs.get(entity).Position);
  ecs.tick(1);
  expect(JSON.stringify(ecs.get(entity).Position))
    .to.deep.equal(position);
  ecs.get(1).Momentum.y = 30;
  ecs.tick(1);
  expect(JSON.stringify(ecs.get(entity).Position))
    .to.deep.equal(JSON.stringify({x: 32, y: 450, z: 0}));
});

it('can create entities when ticking systems', () => {
  const ecs = new Ecs();
  class Spawn extends System {

    tick() {
      this.createEntity();
    }

  }
  ecs.addSystem(Spawn);
  ecs.create();
  expect(ecs.get(2))
    .to.be.undefined;
  ecs.tick(1);
  expect(ecs.get(2))
    .to.not.be.undefined;
});

it('can schedule entities to be deleted when ticking systems', () => {
  const ecs = new Ecs();
  class Despawn extends System {

    tick() {
      this.destroyEntity(1);
    }

  }
  ecs.addSystem(Despawn);
  ecs.createExact(1);
  ecs.tick(1);
  expect(ecs.get(1))
    .to.not.be.undefined;
  ecs.tickFinalize();
  expect(ecs.get(1))
    .to.be.undefined;
});

it('can add components to and remove components from entities when ticking systems', () => {
  const Foo = {bar: 'uint8'};
  const ecs = new Ecs({Foo});
  class AddComponent extends System {

    tick() {
      this.insertComponents(1n, {Foo: {}});
    }

  }
  class RemoveComponent extends System {

    tick() {
      this.removeComponents(1n, ['Foo']);
    }

  }
  ecs.addSystem(AddComponent);
  ecs.createExact(1);
  ecs.tick(1);
  expect(ecs.get(1).Foo)
    .to.not.be.undefined;
  ecs.removeSystem(AddComponent);
  ecs.addSystem(RemoveComponent);
  ecs.tick(1);
  expect(ecs.get(1).Foo)
    .to.be.undefined;
});

it('can encode and decode an ecs', () => {
  const ecs = new Ecs({Empty, Position});
  const entity = ecs.create({Empty: {}, Position: {y: 420}});
  const view = new DataView(new ArrayBuffer(1024));
  ecs.encode([[entity, true]], view);
  const newEcs = new Ecs({Empty, Position});
  newEcs.decode(view);
  expect(JSON.stringify(newEcs.get(entity)))
    .to.deep.equal(JSON.stringify(ecs.get(entity)));
  ecs.setClean();
  ecs.encode([[entity, true]], view);
  const newEcs2 = new Ecs({Empty, Position});
  newEcs2.decode(view);
  expect(newEcs2.get(entity))
    .to.be.undefined;
  ecs.encode([entity], view);
  newEcs2.decode(view);
  expect(newEcs2.get(entity))
    .to.not.be.undefined;
});

it('can add bundles', () => {
  const Height = {height: 'uint32'};
  const Width = {width: 'uint32'};
  const Area = ['Height', 'Width'];
  class ConfiguredArea extends Bundle {

    static configure({height, width}) {
      return {Height: {height}, Width: {width}};
    }

    static Components = ['Height', 'Width'];

  }
  const ecs = new Ecs({
    Area,
    ConfiguredArea,
    Height,
    Width,
  });
  const entity = ecs.get(ecs.create({Area: {Width: {width: 420}}}));
  expect(entity.Height.height)
    .to.equal(0);
  expect(entity.Width.width)
    .to.equal(420);
  const configuredEntity = ecs.get(ecs.create({ConfiguredArea: {width: 420}}));
  expect(configuredEntity.Height.height)
    .to.equal(0);
  expect(configuredEntity.Width.width)
    .to.equal(420);
});