fix: permission error with pb.load_dataset() for duckdb on Windows

[matt-humphrey]

Summary

There was an error with loading temporary file for duckdb on Windows.
I changed the code to explicitly close the Ibis connection, and that seems to have resolved the problem.

Related GitHub Issues and PRs

• Ref: fix: Permission Error trying to use pb.load_data_set() with duckdb on Windows #244

[matt-humphrey]

My bad, I should have run all tests before pushing changes.

From what I gather, when pb.load_dataset() is used with duckdb, it's returning a live connection to the Ibis table. Hence a bunch of these tests failed, because I explicitly closed the connection.

The problem appears to be that Windows runs into permission errors due to maintaining that live connection beyond the function where that connection is defined. I'm not sure what an optimal solution is here - possibly converting the file into memory, and then closing the connection?

[EDIT]

Upon further investigation, part of the problem likely has to do with the test fixtures also returning live connections, for example:

@pytest.fixture
def tbl_dates_times_text_duckdb():
    file_path = pathlib.Path.cwd() / "tests" / "tbl_files" / "tbl_dates_times_text.ddb"
    with tempfile.TemporaryDirectory() as tmp:
        fpath: Path = Path(tmp) / "tbl_dates_times_text.ddb"
        shutil.copy(file_path, fpath)
        return ibis.connect(f"duckdb://{fpath!s}").table("tbl_dates_times_text")

Part of the solution might be changing these fixtures also.