rejects.toThrow in Jest

Question

I have created this class:

export class ErrorList  {

  
    public HostelNotFoundError(details: ErrorDetail): FunctionalError {
        return new FunctionalError('1', 'Can\'t find this hostel', details);
    }

and in the service:

throw new ErrorList().HostelNotFoundError({} });

I would like to know if in Jest is possible to do something like:

rejects.toThrow(HostelNotFoundError);

isn't the actual thrown error `FunctionalError ` ? take a look at this https://stackoverflow.com/questions/46042613/how-to-test-type-of-thrown-exception-in-jest — Arjun Nayak, Jun 22 '20 at 11:16

score 2 · Accepted Answer · answered Jun 22 '20 at 12:40

HostelNotFoundError is not of type FunctionalError, it is a method of the ErrorList class that returns a new instance of FunctionalError. So in your unit-test you have to use:

rejects.toThrow(FunctionalError);

Note that you can use toMatch to validate e.g. the error-message or toMatchObject to validate the error's properties:

rejects.toMatch('Can\'t find this hostel');

rejects.toThrow in Jest

1 Answers1