Deep sweep test coverage geotiff 2026 05 11 (#1596)

* Cover dask-streaming codec gap and cubic overview

Adds test_streaming_codecs_2026_05_11.py with 9 tests for the codec
paths in the dask streaming writer and the scipy-backed cubic overview
resampler that were not exercised in the existing test matrix:

- TestStreamingLerc: lossless round-trip, lossy max_z_error budget,
  and eager-vs-streaming byte-for-byte parity.
- TestStreamingLz4: round-trip and eager parity.
- TestStreamingPackbits: uint8 round-trip and eager parity.
- TestCubicOverview: scipy.ndimage.zoom code path exercised via COG
  write, including a quadratic-ramp test that distinguishes cubic
  from mean output.

The eager writer covered these codecs already; the streaming path
that fires for dask-backed inputs feeds the same _compress_block but
had no test coverage for these codecs. Cubic overview routed through
scipy was likewise untested.

Updates .claude/sweep-test-coverage-state.csv for the 2026-05-11
test-coverage sweep run on geotiff.

* Remove unused imports in streaming codec tests

ruff flagged `os` and `dask.array as darr` as unused. Replace the
bound `dask = pytest.importorskip("dask")` with a discarding call.

* Soften incorrect packbits-only-uint8 claim in test commentary

Copilot flagged the docstring and section comment claiming packbits in
this writer only supports uint8. packbits operates on the raw byte
stream, so any dtype is technically supported; uint8 is just the variant
this test exercises (and the dtype packbits was designed for).

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: brendancol <433221+brendancol@users.noreply.github.com>

Author: brendancol

xrspatial/geotiff/tests/test_streaming_codecs_2026_05_11.py

@@ -9,8 +9,10 @@
 * Dask streaming write + LERC (lossless and lossy ``max_z_error``)
   produces identical output to the eager writer.
 * Dask streaming write + LZ4 round-trips a float32 raster.
-* Dask streaming write + packbits round-trips a uint8 raster (the only
-  dtype packbits supports in this writer).
+* Dask streaming write + packbits round-trips a uint8 raster. packbits
+  operates on the raw byte stream so any dtype is technically supported;
+  uint8 is the variant exercised here and the one packbits was designed
+  for (run-length encoding of byte runs).
 * COG output with ``overview_resampling='cubic'`` round-trips through
   scipy.ndimage.zoom (the only overview method that takes a separate
   code path in ``_block_reduce_2d``).
@@ -139,7 +141,7 @@ def test_streaming_matches_eager(self, float_raster, dask_float_raster,
 
 
 # ---------------------------------------------------------------------------
-# packbits: round-trip on uint8 (the only supported dtype)
+# packbits: round-trip on uint8 (the dtype packbits is designed for)
 # ---------------------------------------------------------------------------
 
 class TestStreamingPackbits: