old_contents: import { module, test } from 'qunit';
  import CartLineItemModel from 'shopify-buy/models/cart-line-item-model';
  import BaseModel from 'shopify-buy/models/base-model';
  
  let model;
  
  const lineItemFixture = {
    id: 3,
    image: 'http://google.com/image.png',
    variant_id: 12345,
    product_id: 45678,
    title: 'Some Product',
    quantity: 1,
    properties: {},
    variant_title: 'Red / Small',
    price: '12.00',
    compare_at_price: '',
    line_price: '12.00',
    grams: 4
  };
  
  module('Unit | CartLineItemModel', {
    setup() {
      model = new CartLineItemModel(lineItemFixture);
    },
  
    teardown() {
      model = null;
    }
  });
  
  test('it extends from BaseModel', function (assert) {
    assert.expect(1);
  
    assert.ok(BaseModel.prototype.isPrototypeOf(model));
  });
  
  test('it updates line_price based on changing quantity', function (assert) {
    assert.expect(/* Add a value here */);
  });
  
  
new_contents: import { module, test } from 'qunit';
  import CartLineItemModel from 'shopify-buy/models/cart-line-item-model';
  import BaseModel from 'shopify-buy/models/base-model';
  
  let model;
  
  const lineItemFixture = {
    id: 3,
    image: 'http://google.com/image.png',
    variant_id: 12345,
    product_id: 45678,
    title: 'Some Product',
    quantity: 1,
    properties: {},
    variant_title: 'Red / Small',
    price: '12.00',
    compare_at_price: '',
    line_price: '12.00',
    grams: 4
  };
  
  module('Unit | CartLineItemModel', {
    setup() {
      model = new CartLineItemModel(lineItemFixture);
    },
  
    teardown() {
      model = null;
    }
  });
  
  test('it extends from BaseModel', function (assert) {
    assert.expect(1);
  
    assert.ok(BaseModel.prototype.isPrototypeOf(model));
  });
  
  test('it updates line_price based on changing quantity', function (assert) {
    assert.expect(6);
  
    assert.equal(model.quantity, 1);
    assert.equal(model.price, '12.00');
    assert.equal(model.line_price, '12.00');
  
    model.quantity = 2;
    assert.equal(model.quantity, 2);
    assert.equal(model.price, '12.00');
    assert.equal(model.line_price, '24.00');
  });
  
subject: complete test for line_price value based on quantity change