angular/components · error

This TestElement was not created by the TestbedHarnessEnviro

Error message

This TestElement was not created by the TestbedHarnessEnvironment

What it means

TestbedHarnessEnvironment.getNativeElement only unwraps UnitTestElement instances it created itself. Passing a TestElement produced by a different environment (e.g. TestbedHarnessEnvironment from another module injector or a non-testbed environment) fails the instanceof check. The library throws instead of returning a wrong/undefined DOM node.

Source

Thrown at src/cdk/testing/testbed/testbed-harness-environment.ts:144

  }

  /**
   * Creates a `HarnessLoader` at the document root. This can be used if harnesses are
   * located outside of a fixture (e.g. overlays appended to the document body).
   */
  static documentRootLoader(
    fixture: ComponentFixture<unknown>,
    options?: TestbedHarnessEnvironmentOptions,
  ): HarnessLoader {
    return new TestbedHarnessEnvironment(document.body, fixture, options);
  }

  /** Gets the native DOM element corresponding to the given TestElement. */
  static getNativeElement(el: TestElement): Element {
    if (el instanceof UnitTestElement) {
      return el.element;
    }
    throw Error('This TestElement was not created by the TestbedHarnessEnvironment');
  }

  /**
   * Creates an instance of the given harness type, using the fixture's root element as the
   * harness's host element. This method should be used when creating a harness for the root element
   * of a fixture, as components do not have the correct selector when they are created as the root
   * of the fixture.
   */
  static async harnessForFixture<T extends ComponentHarness>(
    fixture: ComponentFixture<unknown>,
    harnessType: ComponentHarnessConstructor<T>,
    options?: TestbedHarnessEnvironmentOptions,
  ): Promise<T> {
    const environment = new TestbedHarnessEnvironment(fixture.nativeElement, fixture, options);
    await environment.forceStabilize();
    return environment.createComponentHarness(harnessType, fixture.nativeElement);
  }

View on GitHub (pinned to 0411926e7d)

Solutions

1. Only pass TestElement instances obtained from the same TestbedHarnessEnvironment (harness.host or environment-level APIs)
2. Use harness.host() and await it to get the environment-created TestElement instead of constructing elements manually
3. Ensure a single copy of @angular/cdk is installed/bundled (check for duplicate @angular/cdk versions in node_modules)
4. Use (el as any).element only if you are certain the element is a UnitTestElement, with a guard

Example fix

// before
const el = someOtherEnv.getTestElement(nativeEl);
const dom = TestbedHarnessEnvironment.getNativeElement(el); // throws
// after
const harness = await loader.getHarness(MyCompHarness);
const testEl = await harness.host();
const dom = TestbedHarnessEnvironment.getNativeElement(testEl); // ok

import { UnitTestElement } from '@angular/cdk/testing/testbed';
if (!(el instanceof UnitTestElement)) {
  throw new Error('Pass a TestElement created by TestbedHarnessEnvironment');
}

import { UnitTestElement } from '@angular/cdk/testing/testbed';
import { TestElement } from '@angular/cdk/testing';
function isUnitTestElement(el: TestElement): el is UnitTestElement {
  return el instanceof UnitTestElement;
}

try {
  const native = TestbedHarnessEnvironment.getNativeElement(el);
} catch (e) {
  if ((e as Error).message.includes('not created by the TestbedHarnessEnvironment')) {
    throw new Error('Obtain the element from the same harness environment');
  }
  throw e;
}

When it happens

Trigger: Calling TestbedHarnessEnvironment.getNativeElement(el) where el was created by another harness environment implementation (e.g. Selenium/Playwright environment, or a UnitTestElement from a different Angular testing module instance).

Common situations: Mixing harness environments across test bundles; sharing TestElement instances between Karma testbed tests and e2e-style environments; multiple copies of @angular/cdk/testing bundled in one app causing instanceof to fail across realms.

Related errors

• This TestElement was not created by the ProtractorHarnessEnv
• This TestElement was not created by the WebDriverHarnessEnvi
• Index must not be negative
• No harness was located at index ${offset}
• CDK Component harness query must contain at least one elemen

AI-assisted analysis of angular/components@0411926e7d (2026-08-31). Data as JSON: /api/errors/66756635a296f4b4. Report an issue: GitHub.