adds condition to check XDG_DATA_HOME to set global_dir value

[goosethedev]

Description

Check for XDG_DATA_HOME env var when setting the global directory for storing pipeline data.

If the variable if set but ~/.dlt exists, then it is used with a warning raised to move it manually and not break backwards compatibility.

Related Issues

• Closes Follow the XDG Base Directory spec for local pipelines' data #2319

Additional Context

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[sh-rp]

thanks for the contribution :) I have one note, and it would be good to have a test for this. maybe in test_run_context.py

[goosethedev]

For the test, for now I have this test passing in test_run_context.py:

def test_context_with_xdg_dir() -> None:
    import tempfile
    temp_data_home = os.path.join(tempfile.gettempdir(), "test")

    os.environ["XDG_DATA_HOME"] = temp_data_home

    ctx = PluggableRunContext()
    run_context = ctx.context
    assert run_context.global_dir == os.path.join(temp_data_home, "dlt")

    os.environ.pop("XDG_DATA_HOME")

As for the failing CI above, it seems I have to do if "XDG_DATA_HOME" in os.environ to avoid a KeyError. I'll fix it and rerun tests locally.

[rudolfix]

@goosethedev are you planning to still work on this? to complete the PR we need to:

1. fix the KeyError
2. add a test that you mentioned in PR. just unit testing global_dir is also good. test_run_context.py is the right place~
3. merge the current devel... we fixed a few tests that stopped working recently (outdated test rest API)

thanks!

[goosethedev]

Sorry for the delay, I was waiting for feedback on the test 😅

I decided to force-push to incorporate the new changes from devel and tidy the changes and test into one single commit. Let me know if everything's OK.