Problem
UxDataArray.to_raster() originally only treated ax.get_xlim() == (0, 1) and ax.get_ylim() == (0, 1) as the default extent case before auto-setting the rasterization extent and warning the user.
That is too narrow for Cartopy GeoAxes: depending on the Cartopy/Matplotlib setup, a newly created axes may still be in its default state while reporting projection-scale/global limits instead of (0, 1). In that case the warning is skipped even though the user never set an extent.
How this showed up in tests
After adding warning assertions to the raster tests, these started failing inconsistently:
test/test_plot.py::test_to_rastertest/test_plot.py::test_to_raster_with_extra_dimstest/test_plot.py::test_to_raster_reuse_mapping
The tests expected the auto-extent warning, but on environments where Cartopy initialized the axes with projection/global limits rather than (0, 1), no warning was emitted.
Root cause
The implementation used one specific default-limit representation ((0, 1)) as a proxy for "user did not set extent". That assumption does not hold across Cartopy/Matplotlib environments.
Resolution
Use ax.get_autoscale_on() as the primary signal that the user has not explicitly set the extent, and then treat a near-global PlateCarree extent as default as well. This keeps the warning behavior consistent when Cartopy supplies projection defaults instead of (0, 1).
Problem
UxDataArray.to_raster()originally only treatedax.get_xlim() == (0, 1)andax.get_ylim() == (0, 1)as the default extent case before auto-setting the rasterization extent and warning the user.That is too narrow for Cartopy
GeoAxes: depending on the Cartopy/Matplotlib setup, a newly created axes may still be in its default state while reporting projection-scale/global limits instead of(0, 1). In that case the warning is skipped even though the user never set an extent.How this showed up in tests
After adding warning assertions to the raster tests, these started failing inconsistently:
test/test_plot.py::test_to_rastertest/test_plot.py::test_to_raster_with_extra_dimstest/test_plot.py::test_to_raster_reuse_mappingThe tests expected the auto-extent warning, but on environments where Cartopy initialized the axes with projection/global limits rather than
(0, 1), no warning was emitted.Root cause
The implementation used one specific default-limit representation (
(0, 1)) as a proxy for "user did not set extent". That assumption does not hold across Cartopy/Matplotlib environments.Resolution
Use
ax.get_autoscale_on()as the primary signal that the user has not explicitly set the extent, and then treat a near-global PlateCarree extent as default as well. This keeps the warning behavior consistent when Cartopy supplies projection defaults instead of(0, 1).