Consolidated the array indexing test suite (tests/test_indexing.py): the loop-and-np.random based selection tests were rewritten as deterministic, parametrized Expect/ExpectFail cases on small arrays, error paths were split into their own named tests, and the two divergent Expect test-case dataclass pairs were unified onto the canonical one in tests/conftest.py (whose ExpectFail now has an optional regex msg and a raises() helper). Test-only change with no effect on the public API.