def test_no_categorize():
df = pd.DataFrame({"a": [i for i in range(99)]})
Items.categorize(df)
assert df.select_dtypes(["category"]).empty
def test_categorize(data, expected_cats):
df = pd.DataFrame(data)
Items.categorize(df)
np.testing.assert_array_equal(
df.select_dtypes(["category"]).columns.values, expected_cats)