How to use this.command.error in unit test?

[schlomo]

I have a Command that has somewhere an exit condition like this:

try {
...
} catch (e) {
  this.command.error(e.message);
}

which works very well as intended. My problem is that I cannot write a Jest unit test for the error situations. When I do then the tes fails like this:

Received message:   "Cannot read properties of undefined (reading 'error')"

      50 |       );
      51 |     } catch (e) {
    > 52 |       this.command.error(e.message);
         |                    ^
      53 |     }
      54 |   }
      55 | }Jest

It seems like this.command is not defined under test. I define my unit test the following way:

describe('AwsProfilesCommand', () => {
  let command: AwsProfilesCommand;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [AwsProfilesCommand],
    }).compile();

    command = module.get<AwsProfilesCommand>(AwsProfilesCommand);
    jest.resetAllMocks();
  });

  it('should test something', async () => {
    await expect(command.run([])).rejects.toThrow('...');
  });
});

I know that this is not the nest-commander-testing way of doing things, which doesn't work well for me because of all the other dependencies in my CLI application. My goal is to test just the one command with minimal mocking of dependencies.

[schlomo]

FYI, I was able to patch in a mock for this.command.error like this:

describe('AwsProfilesCommand', () => {
  let command: AwsProfilesCommand;
  let cr_mock: any;

  beforeEach(async () => {
    const module: TestingModule = await Test.createTestingModule({
      providers: [AwsProfilesCommand],
    }).compile();

    command = module.get<AwsProfilesCommand>(AwsProfilesCommand);
    cr_mock = (command as any).command = createMock<CommandRunner>();

    jest.resetAllMocks();
  });

  it('should throw an error', async () => {
    await command.run([]);
    expect(cr_mock.error).toHaveBeenLastCalledWith(
      'File XXXXXX does not exist, run login or setup first',
    );
  });

Not sure if this is really a good solution, happy for other - better - ideas.