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Troubleshooting

This page covers common issues you may encounter when using ngx-testbox.

setInterval prevents stabilization​

Symptom​

  • Sync (fakeAsync): MaximumAttemptsToStabilizeFixtureReachedError
  • Async (runTasksUntilStableAsync): LongRunningComponentError
  • Or: "1 periodic timer(s) still in the queue"

Diagnosis​

Enable debug: true to see a console warning with the stack trace of where setInterval is called:

runTasksUntilStable(fixture, {debug: true});
// or
await runTasksUntilStableAsync(fixture, {debug: true});

Solutions​

  1. Mock the setInterval usage in your tests.
  2. Run it outside the Angular zone: 
    this.ngZone.runOutsideAngular(() => setInterval(...));
warning

In Angular 17 and earlier, runOutsideAngular + fakeAsync may still leave periodic timers in the queue. Use discardPeriodicTasks() at the end of the test as a workaround. Starting from Angular 18 this is resolved.

Unused HTTP instruction error​

Symptom​

HttpInstructionWasNotExecutedDuringFixtureStabilizationError

Cause​

You provided an instruction but your component never made the matching HTTP request.

Solutions​

  • Remove the unused instruction.
  • Verify your component actually triggers the request (check ngOnInit, event handlers, etc.).
  • If the request is conditional, only add the instruction in the relevant test case.
  • Double check similar URLs of your instructions. The most specific URL checkers must be defined closer to the beginning of http instructions' array.

Unhandled HTTP request error​

Symptom​

NoMatchingHttpInstructionForRequestFoundError

Cause​

Your component made an HTTP request that did not match any of the provided instructions.

Solutions​

  • Add the missing instruction to httpCallInstructions.
  • Double-check the URL string (exact match vs .includes() behavior) and the HTTP method.
  • Use debug: true to inspect the pending request URL and method.

Promise in fakeAsync response getter​

Symptom​

CannotUsePromiseResponseWithinFakeAsync

Cause​

You passed a response getter that returns a Promise to runTasksUntilStable (which runs inside fakeAsync).

Solutions​

  • Switch to the async/await approach (runTasksUntilStableAsync).
  • Make the response getter synchronous.

Timeout in async/await tests​

Symptom​

LongRunningComponentError

Cause​

The component did not stabilize within componentLongRunTimeout (default: 10 seconds).

Solutions​

  • Check for leaked setInterval or setTimeout calls (see above).
  • Increase componentLongRunTimeout if the component legitimately takes longer: 
    await runTasksUntilStableAsync(fixture, {
      componentLongRunTimeout: 30_000,
    });

Zoneless delayed work is not keeping the fixture unstable​

If your app is zoneless and a timeout or interval should count toward fixture stability, use Angular's PendingTasks.

This is especially important when delayed work happens before the first HTTP request is created. Without PendingTasks, runTasksUntilStableAsync can finish early because Angular may consider the fixture stable even though your component still has delayed work to do.

If the timer comes from a third-party library and you cannot reasonably instrument it with PendingTasks, mock that library or the code path that depends on it in the test.

If you see HttpInstructionWasNotExecutedDuringFixtureStabilizationError in this situation, it usually means the component never reached the delayed code path during stabilization.

HTTP requests don't affect zone stability​

In some Angular versions, the fixture may report as stable even while HTTP requests are pending. Ngx-testbox handles this internally by checking the HTTP testing queue directly, so this is not a concern for users.