How to Handle Jest Unit Testing for cmp in a React-in-Angular Hybrid App

Question

Can you tell me how to Handle Jest Unit Testing for 'ɵcmp' in a React-in-Angular Hybrid App? Use code snippets if possible.

Answer 1

Encountering the 'ɵcmp' property error during Jest unit testing in a React-in-Angular hybrid application typically indicates issues with Angular's internal component metadata, especially when dealing with Angular's standalone components. To address this, consider the following steps:

Ensure Proper Configuration:

Dependencies: Verify that all necessary dependencies for both Angular and Jest are correctly installed.

Jest Configuration: Ensure that Jest is properly configured to handle Angular components. This may involve setting up appropriate presets and transformers.

Update TestBed Configuration:

When testing Angular components, especially standalone ones, ensure they are correctly declared in the TestBed configuration. For example:

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

import { WrapperComponent } from './wrapper.component';

import { CUSTOM_ELEMENTS_SCHEMA } from '@angular/core';

describe('WrapperComponent', () => {

  beforeEach(async () => {

    await TestBed.configureTestingModule({

      declarations: [WrapperComponent],

      schemas: [CUSTOM_ELEMENTS_SCHEMA], // Add this line

    }).compileComponents();

  });

  // Add your tests here

});

Including CUSTOM_ELEMENTS_SCHEMA can help Jest recognize custom elements and prevent errors related to Angular's internal properties.

Mock External Dependencies:

In a hybrid application, components may rely on services or modules from both React and Angular. Ensure that these dependencies are adequately mocked to isolate the component under test.