Validators do not implement __eq__ method

[michaelurban]

Rest Framework validators do not implement the __eq__ method like many of their Django counterparts.

The expression ProhibitSurrogateCharactersValidator() == ProhibitSurrogateCharactersValidator() evaluates to False when it would be useful to have it evaluate to True, especially in tests.

[auvipy]

would you mind come with at least one draft implementation of this? I need to see what we can actually achieve with it. I can recall something like this in django core but can't remember exact usecases

[michaelurban]

Implementation - It's in the core validators: https://github.com/django/django/blob/stable/4.2.x/django/core/validators.py#L57

A use case is to be able to test whether a validator appears in a serializer's list of validators. For example: self.assertIn(ValidatorThatImplementsEq(), field.validators)

For this to work lazy formatted validator messages would also need to implement __eq__ IIRC. __eq__ is something they should support regardless.

assert django_validators.MinLengthValidator(
  min_length,
  message=lazy_format(
    field.error_messages["min_length"],
    min_length=min_length,
  ),
) == field.validators[0], 'This will always be "False" because "lazy_format" does not implement "__eq__"'

and

assert str(
    django_validators.MinLengthValidator(
        10,
        message=lazy_format(
            field.error_messages["min_length"],
            min_length=10,
        ),
    ).message
) != str(
    field.validators[1].message
), 'These will be equal because "lazy_format" will evaluate to the same string value'

Serializer fields are difficult to test declaratively because of these omissions.

I'm running into these issues while creating field asserts for my serializers like I use for my models.

self.assertCharField(
    RandomSerializer._declared_fields["name"],
    min_length=10,
    max_length=100,
    allow_blank=True,
)

How could anyone test their serializer field definitions declaratively w\o the __eq__-s? I'm falling back to converting the error messages to strings and comparing them.

[auvipy]

as it is a django compat stuff, I am open to contribution in this regard

[michaelurban]

So is this getting labeled as accepted and put on the todo pile?

[auvipy]

yes