[brendancol]

Closes #2428. Cluster 4 of long-tail epic #2424. Tests-only.

Summary

Fold seven top-level coord-edge-case files into the existing
xrspatial/geotiff/tests/read/test_coords.py:

• test_coord_regularity_1720.py
• test_coords_1813.py
• test_coords_to_transform_3d_1643.py
• test_int_coord_sentinel_2087.py
• test_int_coords_round_trip_hotfix_1962.py
• test_multi_tiepoint_validation_2117.py
• test_rational_zero_denominator_2313.py

The boundary file test_non_uniform_coords_alias_2215.py also folds
cleanly because the alias resolution layers onto the same writer-side
_coords_to_transform validation already covered in section 5; it lands
in the same section rather than waiting for a follow-up.

Sections in the extended file

1. coords_from_pixel_geometry / transform_tuple_from_pixel_geometry
   / coords_from_geo_info helpers.
2. _extract_transform multi-tiepoint consistency.
3. Zero-denominator RATIONAL / SRATIONAL rejection.
4. Descending / ascending coord round trip (pre-existing from Epic: Consolidate the GeoTIFF test suite (354 files → ~50) #2390).
5. _coords_to_transform writer-side validation: regularity (1D),
   3D (y, x, band) / (band, y, x), and alias-aware
   NonUniformCoordsError across y/x, lat/lon,
   latitude/longitude, row/col.
6. Integer-coord round trip and the _NO_GEOREF_KEY marker.
   Integration sub-cluster gated on XRSPATIAL_RUN_INTEGRATION=1.

Audit

xrspatial/geotiff/tests/CLUSTER_AUDIT_COORDS.md maps every old
file::test to its new file::test_id. The audit file is deleted on a
final commit before merge.

Verification

• pytest xrspatial/geotiff/tests/read/test_coords.py -v: 101 passed,
  2 skipped (integration-gated).
• pytest xrspatial/geotiff/tests/ -x -q: 5817 passed, 68 skipped,
  2 xfailed.
• find xrspatial/geotiff/tests -name 'test_*.py' | wc -l: 242
  (was 249; -7 deleted, +0 added because test_coords.py already
  existed).

Test plan

• New read/test_coords.py passes on this checkout.
• Full xrspatial/geotiff/tests/ suite passes.
• CI green across numpy / cupy / dask+numpy / dask+cupy.
• Audit file deleted on the pre-merge commit.

[brendancol]

PR Review: geotiff tests: consolidate coords cluster

Blockers

None.

Suggestions

None.

Nits

• xrspatial/geotiff/tests/read/test_coords.py:68-78: the local _gpu_available() helper and _HAS_GPU constant duplicate the shared requires_gpu marker from ..conftest. The 3D-roundtrip GPU test could swap @pytest.mark.skipif(not _HAS_GPU, reason="cupy + CUDA required") for @requires_gpu and drop the local probe. The original test_coords_to_transform_3d_1643.py carried the same local helper, so this is a faithful fold; worth tidying in a follow-up.
• xrspatial/geotiff/tests/read/test_coords.py:94-110: _make_da (float32 sequential) and _make_da_uint8 (uint8 zeros) sit next to each other and take the same (x_coords, y_coords) arg order. A one-line note in each docstring about which sections use which would save a reader from grepping.

What looks good

• Test count parity verified: 103 collected before, 103 after. I checked out the prior commit and re-collected to confirm.
• Full suite is 5817 passed, 68 skipped, 2 xfailed.
• CLUSTER_AUDIT_COORDS.md maps every old file::test to its new id, including the parametrized variants. PR body says it gets deleted in a pre-merge commit.
• Boundary call on test_non_uniform_coords_alias_2215.py was folded into section 5 instead of being deferred. The alias-resolution tests really do belong with the rest of the _coords_to_transform writer-side checks.
• Sections are ordered low-level helpers first, then tiepoint, RATIONAL, round trip, writer validation, integer-coord marker. Easy to scan.
• Integration cases stayed behind requires_integration.
• No xrspatial/geotiff/ source touched.

Checklist

• All consolidated tests pass on this checkout
• Test count parity verified (103 = 103)
• No source changes
• Audit file present and complete
• No pyflakes warnings
• Stays in lane (read/test_coords.py)

[brendancol]

Follow-up after nit fixes (d707736)

Both nits from the previous pass are addressed in d707736:

• The local _gpu_available() / _HAS_GPU pair is gone. test_write_geotiff_gpu_roundtrip_3d now uses @requires_gpu from _helpers/markers.py via the conftest re-export. importlib.util import dropped.
• The shared-helpers block carries a comment explaining when to use _make_da (float32 sequential, for round-trip / orientation tests in section 4) versus _make_da_uint8 (uint8 zero, for the _coords_to_transform regularity checks in section 5).

Re-ran after the fixes:

• pytest xrspatial/geotiff/tests/read/test_coords.py -q: 101 passed, 2 skipped.
• pyflakes: clean.

No remaining blockers, suggestions, or nits.