I have a Angular Workspace which has a “shared” project. In the shared project I’ve added a simple testService:

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

@Injectable({
  providedIn: 'root'
})
export class TestService {

constructor() { }
  public someFunction(): void {
    console.log('void')
  }
}

I’ve exported the file from my “shared/scr/public.api.ts” file. And imported the TestService in my component:

import { Component, OnInit, inject } from '@angular/core';
import { TestService } from 'shared';

@Component({
  selector: 'app-test-flow',
  templateUrl: './app.component.html',
})
export class AppComponent implements OnInit {
  constructor(
  private testService: TestService
  ) {}

  ngOnInit(): void {
    this.testService.someFunction();

  }
}

My spec:

import { TestBed } from '@angular/core/testing';
import { AppComponent } from './app.component';
import { HttpClientTestingModule } from '@angular/common/http/testing';
import { TestService } from 'shared';

describe('AppComponent', () => {
  let testService: TestService;

  beforeEach(() => {
    TestBed.configureTestingModule({
      imports: [
        HttpClientTestingModule,
      ]
    });
    testService = TestBed.inject(TestService);
  });

  it('should create the app', () => {
    const fixture = TestBed.createComponent(AppComponent);
    const app = fixture.componentInstance;
    expect(app).toBeTruthy();
  });
});

When I run a test, I get the error: “Cannot read properties of undefined (reading ‘hasOwnProperty’)”.

  app.component.spec.ts (95.998 s)
  ● AppComponent › should create the app

    TypeError: Cannot read properties of undefined (reading 'hasOwnProperty')

      20 |     });
    > 21 |     testService = TestBed.inject(TestService);
      22 |   });

      at R3Injector.get (../../node_modules/@angular/core/fesm2022/core.mjs:2279:15)
      at _TestBedImpl.inject (../../node_modules/@angular/core/fesm2022/testing.mjs:1573:48)
      at Function.inject (../../node_modules/@angular/core/fesm2022/testing.mjs:1444:34)

The error doesn’t show when I don’t import the testService from the shared module.

My jest.config.ts looks like this

import type { Config } from 'jest';

const jestConfig: Config = {
  preset: 'jest-preset-angular',
  setupFilesAfterEnv: ['<rootDir>/../../setup-jest.ts'],
  transform: {
    '^.+\.(ts|js|mjs|html|svg)$': [
      'jest-preset-angular',
      {
        tsconfig: '<rootDir>/tsconfig.spec.json',
        stringifyContentPathRegex: '\.(html|svg)$',
      },
    ],
  },
  transformIgnorePatterns: ['<rootDir>/../../node_modules/'],
  moduleNameMapper: {
    '^@test/(.*)$': '<rootDir>/../../mocks/unittest/$1/',
    '^shared': '<rootDir>/../../dist/shared/index.d.ts/',
  },
  moduleDirectories: [
    '<rootDir>/../../node_modules',
  ],
};

export default jestConfig;