No coverage for `__imatmul__` (`@=`)

[haroune-dev]

It looks like __imatmul__ currently lacks test coverage in the suite. A broken implementation (e.g. one raising AttributeError) can pass array_api_tests without triggering any failures.

Checking the codebase:

• imatmul isn't referenced anywhere under array_api_tests/.
• test_iop only covers elementwise binary ops, so matmul isn't included.
• test_linalg.py tests namespace.matmul() directly, but doesn't exercise @ or @=.

Happy to send a PR adding @= coverage if needed!

[ev-br]

Yeah, testing @ and @= could be nice. PR welcome!

IIRC many actual libraries implement a @= b as a = a @ b (e.g. https://numpy.org/doc/2.5/reference/arrays.ndarray.html does not list __imatmul__).

For @ there is a TODO comment,

array-api-tests/array_api_tests/test_linalg.py

Line 403 in ef5b39f

# TODO: Make this also test the @ operator