ValidationError assertion not working when pytest shows the same values-CodePudding

I'm writing a unit test whereby I want to assert that the error I get:

<ValidationError: "'a list' is not of type 'array'">

is equal too

assert ValidationError(message="'a list' is not of type 'array'")

I'm using a simple assertion:

assert actual == expected

When I run pytest I get the following error:

 assert <ValidationError: "'a list' is not of type 'array'"> == <ValidationError: "'a list' is not of type 'array'">

The validation error comes from jsonschema

from jsonschema import ValidationError

Even though they are identical, the assertion still fails. Does anyone know why?

CodePudding user response：

Normally I would structure this using pytest.raises

def test_validation_error():
    with pytest.raises(ValidationError, match="'a list' is not of type 'array'"):
        # whatever you are doing to raise the error
        assert ValidationError(message="'a list' is not of type 'array'")

CodePudding user response：

This exception doesn't seem to have __eq__ method defined, so it is being compared using ids - and since those are 2 different objects, they have different ids. Just like this code will throw an error, because Python doesn't really know how 2 different TypeErrors should be compared.

assert TypeError('a') == TypeError('a')

If you check pytest documentation, suggested way to handle expected exceptions looks like this:

def test_zero_division():
    with pytest.raises(ZeroDivisionError):
        1 / 0