[python-package] Improve pandas categorical test coverage - #7376

[python-package] Improve pandas categorical test coverage#7376

jameslamb merged 11 commits into

lightgbm-org:mainlightgbm-org/LightGBM:mainfrom

maxzw:tests/pandas-categorical-null-and-registred-but-unobservedmaxzw/LightGBM:tests/pandas-categorical-null-and-registred-but-unobservedCopy head branch name to clipboard