Adjust tests to new pandas behavior

tests/test_formula.py

@@ -480,19 +480,29 @@ def test_all_names_against_from_pandas(df, categorical_format):
         pytest.param(
             "1 + C(cat_1, spans_intercept=False) * cat_2 * cat_3",
             id="custom_contrasts",
+            marks=pytest.mark.xfail(
+                reason="Non-uniform categorical formats are not yet supported"
+            ),
         ),
     ],
 )
 def test_names_against_pandas(df, formula, ensure_full_rank):
+    if ensure_full_rank:
+        categorical_format = "{name}[T.{category}]"
+    else:
+        categorical_format = "{name}[{category}]"
+
     num_in_scope = 2  # noqa
+
     model_df = formulaic.model_matrix(formula, df, ensure_full_rank=ensure_full_rank)
     model_tabmat = tm.from_formula(
         formula,
         df,
         ensure_full_rank=ensure_full_rank,
-        categorical_format="{name}[T.{category}]",
+        categorical_format=categorical_format,
         context=0,
     )
+
     assert model_tabmat.model_spec.column_names == model_df.model_spec.column_names
     assert model_tabmat.model_spec.column_names == tuple(model_df.columns)
     assert model_tabmat.column_names == list(model_df.columns)