Unexpected ability checking behavior

Describe the bug Result of ability checking not obviously depends on ability definition

To Reproduce Steps to reproduce the behavior:

1. Ability configuration (rules, detectSubjectType, etc)

class Lot {
  constructor(
    public id: number,
    public isPublished: boolean,
    public userId: number,
  ) {}
}

class User {
  constructor(public id: number) {}
}

enum Action {
  Manage = 'manage',
  Create = 'create',
  Read = 'read',
  Update = 'update',
  Delete = 'delete',
}

type Subjects = typeof Lot | Lot | 'Lot';

export type LotAbility = Ability<[Action, Subjects]>;

export class LotAbilityFactory {
  createForUser(user: User) {
    const { can, build, rules } = new AbilityBuilder<LotAbility>(
      Ability as AbilityClass<LotAbility>,
    );

    can(Action.Read, 'Lot');
    can(Action.Update, Lot);

    console.log('rules', rules);

    return build();
  }
}

1. How do you check abilities

const user = new User(1);
const lot = new Lot(2, false, user.id);
const lotAbility = new LotAbilityFactory().createForUser(user);

lotAbility.can(Action.Update, lot); // false

Expected behavior Obviously that lot is a instance of Lot and it’s should be matched with can(Action.Update, Lot) and return true

Interactive example (optional, but highly desirable) My example and Rewritten example

CASL Version

“@casl/ability”: “5.2.1”,

Environment:

node -v v15.5.1 ts-node -v v9.1.1 “typescript”: “4.0.5”

[Blaze34]

Alternatively, you may use strings and replace can(Action.Update, Lot); with can(Action.Update, ‘Lot’); (pay attention that the 2nd argument is a string!)

I found out it while was testing, but it’s unobviously. Anyway documentation is confusing and should be fixed asap.

[stalniy]

PR to nestjs - https://github.com/nestjs/docs.nestjs.com/pull/1687