code: def test_dataframe_requires_all_categorical(data):
      data = data.assign(B=1)
      enc = dask_ml.preprocessing.OneHotEncoder()
      with pytest.raises(ValueError) as e:
          enc.fit(data)
  
      assert e.match("All columns must be Categorical dtype")
  
imports: import dask.array
  import dask.dataframe
  import numpy
  import packaging.version
  import pandas
  import pytest
  import scipy.sparse
  import sklearn.preprocessing
  import dask_ml.preprocessing
  from dask_ml._compat import DASK_2_20_0, PANDAS_VERSION
  from dask_ml.utils import assert_estimator_equal
label_desc: Use image node_id 7 for calling a global function with example usage: test_dataframe_requires_all_categorical(data) without return types