* Clarify next-gen auto_attribs inference rules
The next-gen auto_attribs api documentation does not clearly describe
cases where (a) only a subset of attributes are annotated and (b)
`field` definitions are provided for a subset of fields. Update
docstring to reflect current, desirable, behavior.
Add tests to clarify `.define` behavior focused on fully-annotated
classes with partially-defined fields, which is commonly used to add
non-default behavior to a subset of a classes fields. For example:
```python
@attr.define
class NewSchool:
x: int
y: list = attr.field()
@y.validator
def _validate_y(self, attribute, value):
if value < 0:
raise ValueError("y must be positive")
```
The previous docstring *could* be read to imply that:
* The new-school API will not infer auto_attribs if there are any
unannotated attributes.
* The new-school API will not infer auto_attribs if *any* attr.ib are
defined, even if those attr.ibs are type annotated.
* Update test to match PR example
* Fix lint error
Co-authored-by: Hynek Schlawack <hs@ox.cx>
2fdf92997c