testing.ts

/**
 * Reconfigures current test suit to prevent angular components compilation after every test run.
 * Forces angular test bed to re-create zone and all injectable services by directly
 * changing _instantiated to false after every test run.
 * Cleanups all the changes and reverts test bed configuration after suite is finished.
 */
export const configureTestSuite = () => {
  const testBedApi: any = getTestBed();
  const originReset = TestBed.resetTestingModule;

  beforeAll(() => {
    TestBed.resetTestingModule();
    TestBed.resetTestingModule = () => TestBed;
  });

  afterEach(() => {
      testBedApi._activeFixtures.forEach((fixture: ComponentFixture<any>) => fixture.destroy());
      testBedApi._instantiated = false;
  });

  afterAll(() => {
      TestBed.resetTestingModule = originReset;
      TestBed.resetTestingModule();
  });
};

This function is very useful if you are trying to speed up the execution of tests for components that take a long time to compile.

Thank you for sharing!

Agreed, many thanks for this 👍

I would just add a line at the top to add imports if you're going to import this file into each spec.ts file:

import { ComponentFixture, getTestBed, TestBed } from '@angular/core/testing';