[Mohit-Ak]

Description

Cats.delete() tested the category with if cat:, so delete(0) fell through to Vect_cat_del and removed every category of the layer; when category 0 was not present it still wiped the layer without raising. The check is now cat is not None.

CatsList.from_array() passed a Python list straight to Vect_array_to_cat_list, which raised ctypes.ArgumentError. It now builds a c_int array first.

Motivation and context

Category 0 is a valid category number, and from_array() had never worked (it was marked TODO: it's not working).

Fixes #8074

How has this been tested?

Added five tests to python/grass/pygrass/vector/tests/test_basic.py: delete(0) leaves the other categories, delete(0) on a layer without it raises ValueError and keeps the layer intact, delete(layer=1) still clears the layer, and from_array with a ranged list and with an empty list. Four of them fail on main and all pass with this change; the rest of test_basic.py (47 tests) and the module doctests pass. ruff/flake8 clean.

Types of changes

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as before)

Checklist

• PR title provides summary of the changes and starts with one of the pre-defined prefixes
• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have updated the documentation accordingly.
• I have added tests to cover my changes.