runTasksUntilStable

Runs Angular change detection and processes tasks until the component fixture is stable. This function is designed to work only within a fakeAsync zone.

It does the following operations:

1. Runs change detection.
2. Responds to HTTP requests.
3. Advances virtual time (tick()).
4. Runs the cycle again until the fixture is stable.

Signature

runTasksUntilStable(
  fixture: ComponentFixture<unknown>,
  params?: RunTasksUntilStableParams
): void

Parameters

fixture

The component fixture to stabilize.

params

Optional configuration object:

Property	Type	Default	Description
httpCallInstructions	HttpCallInstruction[]	[]	Instructions for matching and responding to HTTP requests.
stabilizationTimeAdvance	number	0	Time in ms to advance the virtual clock on each stabilization attempt. This is cumulative across attempts.
maxAttempts	number	30	Maximum stabilization cycles before throwing.
debug	boolean	false	Logs warnings when setInterval is detected.

Throws

• MaximumAttemptsToStabilizeFixtureReachedError — when the fixture cannot stabilize within maxAttempts cycles.
• HttpInstructionWasNotExecutedDuringFixtureStabilizationError — when an instruction was never matched.
• NoMatchingHttpInstructionForRequestFoundError — when an HTTP request did not match any instruction.
• CannotUsePromiseResponseWithinFakeAsync — when a response getter returns a Promise.

Example

import {fakeAsync} from '@angular/core/testing';
import {runTasksUntilStable, predefinedHttpCallInstructions} from 'ngx-testbox/testing';

it('should load users', fakeAsync(() => {
  const fixture = TestBed.createComponent(UserListComponent);

  runTasksUntilStable(fixture, {
    httpCallInstructions: [
      predefinedHttpCallInstructions.get.success('/api/users', () => [
        {id: 1, name: 'Alice'},
      ]),
    ],
  });

  expect(fixture.componentInstance.users.length).toBe(1);
}));

Remarks

• This function processes only HTTP requests made using Angular HttpClient.
• After calling runTasksUntilStable, the fixture is guaranteed to be stable.
• When setInterval is used inside the Angular zone, stabilization may fail. Use debug: true to detect it.
• stabilizationTimeAdvance is a per-attempt time step, not a one-time wait. For timer-driven flows, tune it together with maxAttempts.
• Rule of thumb: stabilizationTimeAdvance * maxAttempts should cover the debounce, throttle, or timer delay you need to flush.

---

ResponseGetter (sync)

The function that generates an HTTP response. Must be synchronous.

type ResponseGetter = (
  httpRequest: HttpRequest<unknown>,
  searchParams: URLSearchParams
) => HttpResponse<any>;

HttpCallInstruction (sync)

A tuple defining how to match and respond to an HTTP request:

type HttpCallInstruction =
  | [HttpCallChecker, ResponseGetter]
  | [HttpCallChecker, ResponseGetter, HttpCallInstructionExtraParams];

HttpCallChecker

Matches an incoming HTTP request:

type HttpCallChecker =
  | ((httpRequest: HttpRequest<unknown>) => boolean)
  | [EndpointPath, HttpMethod];