metamask-extension/test/unit/app/controllers/token-rates-controller.js

import assert from 'assert'
import sinon from 'sinon'
import { ObservableStore } from '@metamask/obs-store'
import TokenRatesController from '../../../../app/scripts/controllers/token-rates'

describe('TokenRatesController', function () {
  it('should listen for preferences store updates', function () {
    const preferences = new ObservableStore({ tokens: [] })
    preferences.putState({ tokens: ['foo'] })
    const controller = new TokenRatesController({ preferences })
    assert.deepEqual(controller._tokens, ['foo'])
  })

  it('should poll on correct interval', async function () {
    const stub = sinon.stub(global, 'setInterval')
    const preferences = new ObservableStore({ tokens: [] })
    preferences.putState({ tokens: ['foo'] })
    const controller = new TokenRatesController({ preferences })
    controller.start(1337)

    assert.strictEqual(stub.getCall(0).args[1], 1337)
    stub.restore()
    controller.stop()
  })
})