wait for

1 wait-for.ts

import Ember from 'ember';
import { assert } from '@ember/debug';

let pending = 0;

export function checkPending(): boolean {
  return pending === 0;
}

export default function waitForInTests(_target: unknown, _propertyKey: string, desc: PropertyDescriptor): void {
  assert('The @waitFor decorator must be applied to functions', desc && typeof desc.value === 'function');

  if (!Ember.testing) {
    return;
  }

  const orig = desc.value;

  desc.value = async function(...args: unknown[]): Promise<unknown> {
    pending++;
    try {
      return await orig.apply(this, args);
    } finally {
      pending--;
    }
  };
}

2 setup.ts

import { registerWaiter, unregisterWaiter } from '@ember/test';
import { checkPending } from 'my-app/utils/wait-for';

/**
 * start the mockserver before each scenario and cleans up after
 * @param hooks
 */
export default function setupWaitFor(hooks: NestedHooks): void {
  hooks.beforeEach(function(): void {
    registerWaiter(checkPending);
  });

  hooks.afterEach(function(): void {
    unregisterWaiter(checkPending);
  });
}

3 usage.js

import { next } from '@ember/runloop';

export default class Foo {
  @waitFor
  doSomething () {
    return next(() => console.log('this should appear before test finishes'));
  }
}