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I don't think anyone asked for this as you did not link issue.

Thanks @pllim for the feedback. I'll open issues for these test additions first and link them before reopening. The motivation is the GSoC 2026 project on hardening astropy's core stability, which specifically calls for a low-level test suite for C/Cython extensions independent of the public API.

GSoC 2026 project on hardening astropy's core stability

Huh. Has GSoC started? Who is your mentor?

Huh. Has GSoC started? Who is your mentor?

GSoC 2026 applications are open until April 8th. I'm in the contributor application phase — not yet accepted. The project is listed at https://openastronomy.org/gsoc/gsoc2026/#/apply with neutrinoceros, astrofrog, and nstarkman as mentors. I'm contributing to astropy to strengthen my application.

Ah, gotcha. In that case, please clarify your motivation in your future PR descriptions and ping a mentor to review. Thanks for your interest.

cc @neutrinoceros @astrofrog @nstarman

Also, I think any maintainer can re-open this PR if they find it valuable and wish to proceed. FYI.

Indeed this is in line with our GSoC proposal. I'll re-open and review now.
@pllim, please feel free to ping me on similar PRs if you see more of them.

Thanks @neutrinoceros Addressed all feedback and squashed to a single commit:

• Renamed file to test_ks_2samp.py
• Renamed test functions (removed redundant suffixes)
• Moved scipy dependency to @pytest.mark.skipif on individual tests only
• Merged three dtype tests into one @pytest.mark.parametrize test
• Removed np.sort() from already-sorted arrays
• Removed changelog fragment

Thanks @neutrinoceros Replaced the manual try/except block with from astropy.utils.compat.optional_deps import HAS_SCIPY as suggested.

Thanks @neutrinoceros Replaced the scipy comparisons with analytically computed expected values and pytest.approx. Removed the scipy dependency entirely since all tests now use hard-coded values. Squashed to a single commit.

In general we use assert_allclose from numpy rather than pytest.approx, so might be worth switching to that for consistency?

Thanks @astrofrog, Switched to assert_allclose from numpy.testing throughout for consistency.

Hi @neutrinoceros - when you get a chance, would appreciate a look at the proposal. Happy to address any feedback before the deadline.