Allow to test for Error instance type

[MonsieurMan]

Clear and concise description of the problem

I like to use custom Error types to help my user manage errors effectively, and I'd like a way to test it simply in vitest.

It seems Jest allows to do so using: https://jestjs.io/docs/expect#tothrowerror, which states it can accept an error class: error object is instance of class.

I tried to find a previous issue or discussion about it in vitest but couldn't, so here's one :)

Suggested solution

Jest implementations allow to do so :

test('Custom error instance', () => {
  expect(drinkOctopus).toThrowError(DisgustingFlavorError);
});

Alternative

As of now, I wrote a test I don't really like which uses a try/catch and an expect(true).to.eq(false) at the end to make it fail if there was no error.

Additional context

I guess it's here I tell you that Vitest is such a pleasure to use and you guys do a great job :)
Happy to help or provide further information if needed !

Validations

• Follow our Code of Conduct
• Read the Contributing Guidelines.
• Read the docs.
• Check that there isn't already an issue that request the same feature to avoid creating a duplicate.

[sheremet-va]

This should already be implemented. Please provide reproduction.

[MonsieurMan]

It works for an error class, I'd say it's only a matter of documenting it here:

https://vitest.dev/api/#tothrowerror

You can provide an optional argument to test that a specific error is thrown:
  - regular expression: error message matches the pattern
  - string: error message includes the substring
+ - error class: error object is instance of class

---

Passing an error instance does not work though, reproduction here: https://stackblitz.com/edit/vitest-dev-vitest-cdj66q?file=test/basic.test.ts

I'd expect vitest to compare class instance, and the message to match in this case.

It's stated as such in Jest's documentation: error object: error message is equal to the message property of the object

[sheremet-va]

@MonsieurMan your reproduction works if I use toThrowError instead of throws which is chai function, and is not documented as Jest-compatible:

- expect(() => throwError()).throws(CustomErrorClass);
+ expect(() => throwError()).toThrowError(CustomErrorClass);

[MonsieurMan]

Will do tomorrow, maybe it's just a matter of documenting it then ! :)

…

On Wed, 13 Jul 2022, 22:37 Vladimir, ***@***.***> wrote: This should already be implemented. Please provide reproduction. — Reply to this email directly, view it on GitHub <#1636 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/ADEAHRU7WFY6GS24PM7A2WDVT4SKFANCNFSM53PMMAPQ> . You are receiving this because you authored the thread.Message ID: ***@***.***>