balena-supervisor/test/lib/chai.ts

import chai from 'chai';
import chaiAsPromised from 'chai-as-promised';
import sinonChai from 'sinon-chai';
import chaiThings from 'chai-things';
import chaiLike from 'chai-like';

/**
 * Mocha runs this EXACTLY ONCE before all tests to set up globals that
 * are used among all test files, such as chai assertion plugins. See
 * https://mochajs.org/#test-fixture-decision-tree-wizard-thing
 *
 * IMPORTANT: The functionality in this global fixture hook should not break any
 * suite run in isolation, and it should be required by ALL test suites.
 * If unsure whether to add to global fixtures, refer to the chart above.
 * Also, avoid setting global mutable variables here.
 */
export const mochaGlobalSetup = function () {
	console.log('Setting up global fixtures for tests...');

	/* Setup chai assertion plugins */
	chai.use(chaiAsPromised);
	chai.use(sinonChai);
	chai.use(chaiLike);
	chai.use(chaiThings);
};