TST: add test to ensure that df.groupby() returns the missing categories when grouping on 2 pd.Categoricals (#35022)
TST: add test to ensure that df.groupby() returns the missing categories when grouping on 2 pd.Categoricals (#35022)


dsm054/pandas,jreback/pandas,gfyoung/pandas,datapythonista/pandas,rs2/pandas,jreback/pandas,gfyoung/pandas,datapythonista/pandas,rs2/pandas,pandas-dev/pandas,gfyoung/pandas,gfyoung/pandas,dsm054/pandas,jreback/pandas,jorisvandenbossche/pandas,jorisvandenbossche/pandas,rs2/pandas,pandas-dev/pandas,datapythonista/pandas,pandas-dev/pandas,dsm054/pandas,dsm054/pandas,rs2/pandas,jorisvandenbossche/pandas,pandas-dev/pandas,jorisvandenbossche/pandas,gfyoung/pandas,jreback/pandas,datapythonista/pandas,dsm054/pandas,jreback/pandas