feature: include enum values in the error message of IsEnum() decorator

[rafaelbeckel]

Description

IsEnum(obj) will produce the same error message, regardless of the expected enum values, which is useless for any practical user-facing application. Returning the message "{obj} must be a valid enum value" does not say anything about the expected input and is not actionable (unless there are some supporting docs somewhere else).

Proposed solution

It should behave like IsIn(Object.values(obj)), which returns the message "{obj} must be one of the following values: cupcakes,lollipops,candies,whatever". This is much nicer and actionable. The end-user cares about the expected values only, not about how they are represented internally.

[NoNameProvided]

Hi! Yeah that is a good idea, although a simple Object.values call won't work because an enum is stored like this:

const MyEnum = {
  '1': "FirstValue",
  '2': "SecondValue",
  "FirstValue": 1,
  "SecondValue": 2
}

(Except if it's a string enum, then it's stored differently.)

This is a good first issue btw if you want to take a look at it.

[hood]

Feature implemented in #887. Waiting for review and approval.

[rpihlak]

Feature implemented in #887. Waiting for review and approval.

When is the pull request going to be merged?

[hood]

Feature implemented in #887. Waiting for review and approval.

When is the pull request going to be merged?

It's been quite a while, right? 🤔

[NoNameProvided]

This feature/fix has been released in 0.14.0.