python/tests/test_indexing.py

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import pyarrow as pa
import pytest
from datafusion import SessionContext


@pytest.fixture
def df():
    ctx = SessionContext()

    # create a RecordBatch and a new DataFrame from it
    batch = pa.RecordBatch.from_arrays(
        [pa.array([1, 2, 3]), pa.array([4, 4, 6])],
        names=["a", "b"],
    )
    return ctx.create_dataframe([[batch]])


def test_indexing(df):
    assert df["a"] is not None
    assert df["a", "b"] is not None
    assert df[("a", "b")] is not None
    assert df[["a"]] is not None


def test_err(df):
    with pytest.raises(Exception) as e_info:
        df["c"]

    for e in ["Schema error", "No field named c"]:
        assert e in e_info.value.args[0]

    with pytest.raises(Exception) as e_info:
        df[1]

    assert (
        "DataFrame can only be indexed by string index or indices"
        in e_info.value.args[0]
    )