import numpy as np import pytest from pandas._libs.internals import BlockPlacement import pandas.util._test_decorators as td import pandas as pd from pandas.core.internals import BlockManager from pandas.core.internals.blocks import ExtensionBlock pytestmark = td.skip_array_manager_invalid_test class CustomBlock(ExtensionBlock): _holder = np.ndarray # Cannot override final attribute "_can_hold_na" @property # type: ignore[misc] def _can_hold_na(self) -> bool: return False @pytest.fixture def df(): df1 = pd.DataFrame({"a": [1, 2, 3]}) blocks = df1._mgr.blocks values = np.arange(3, dtype="int64") bp = BlockPlacement(slice(1, 2)) custom_block = CustomBlock(values, placement=bp, ndim=2) blocks = blocks + (custom_block,) block_manager = BlockManager(blocks, [pd.Index(["a", "b"]), df1.index]) return pd.DataFrame(block_manager) def test_concat_axis1(df): # GH17954 df2 = pd.DataFrame({"c": [0.1, 0.2, 0.3]}) res = pd.concat([df, df2], axis=1) assert isinstance(res._mgr.blocks[1], CustomBlock)