Exception wrapper is broken

I’m submitting a…

[ ] Regression 
[X] Bug report
[ ] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

When I’m testing type of exception’s instance are not equals. This code should work:

it.only('when user doesn"t exist in the Ldap', async () => {
        service.getUserByUid = jest.fn().mockReturnValueOnce(null);
        await expect(service.removeUser(params.user)).rejects.toBeInstanceOf(UserNotFoundException);
});

When you’re using instanceof operator the types are not same.

it.only('when user doesn"t exist in the Ldap', async () => {
        service.getUserByUid = jest.fn().mockReturnValueOnce(null);
        service
          .removeUser(params.user)
          .then(e => {
            console.log(e);
          })
          .catch(e => {
            const x = new UserNotFoundException();
            const er = e instanceof UserNotFoundException;
            const xe = x instanceof UserNotFoundException;
          });
        // await expect(service.removeUser(params.user)).rejects.toBeInstanceOf(UserNotFoundException);
      });

import { NotFoundException } from '@nestjs/common';

export class UserNotFoundException extends NotFoundException {
  constructor(userID: number | string = -1) {
    const msg = `The user: ID - ${userID} not found`;
    super(msg);
  }
}

public async removeUser(userToDelete: UserUpdateDto): Promise<void> {
    const user = await this.getUserByUid(userToDelete.username);
    if (!user) {
      throw new UserNotFoundException();
    }
  }

Expected behavior

e instanceof UserNotFoundException; should be true.

Environment

Nest version: 4.6.6

[Caballerog]

Hi @kamilmysliwiec,

I think that you’re misunderstanding about my issue.

The problem is that the exception’s instance is not correct. I think that NestJS is altering the exception’s instance when is returned from my service (throw new UserNotFoundException).

service
          .removeUser(params.user)
          .then(e => {
            console.log(e);
          })
          .catch(e => {
            const x = new UserNotFoundException();
            const er = e instanceof UserNotFoundException; // er must be true but it's false!!!!
            const xe = x instanceof UserNotFoundException; // this works
          });

Working hard with Nest! 😃

[kamilmysliwiec]

Hi @Caballerog, I’m glad that you found a solution! Hope Victoria was tasty and super helpful 😄