Programmatically comparing Python version strings#

I found myself wanting to compare the version numbers 0.63.1, 1.0 and the 1.0a13 in Python code, in order to mark a pytest test as skipped if the installed version of Datasette was pre-1.0.

This is very slightly tricky, because 1.0 is a higher version than 1.0a13 but comparing it based on string comparison or a tuple of components split by . would give the wrong result.

It turns out the packaging.version Python package solves this exact problem:

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python -m pip install packaging

Then:

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from packaging.version import parse
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v_1_0 = parse("1.0")
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v_1_0a13 = parse("1.0a13")
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v_0631 = parse("0.63.1")

And some comparisons:

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>>> v_1_0 > v_1_0a13
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True
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>>> v_1_0 < v_1_0a13
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False
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>>> v_0631 < v_1_0
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True
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>>> v_0631 < v_1_0a13
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True

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from datasette import version
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from packaging.version import parse
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import pytest
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@pytest.mark.asyncio
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@pytest.mark.skipif(
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    parse(version.__version__) < parse("1.0a13"),
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    reason="uses row_actions() plugin hook",
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)
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async def test_row_actions():
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    # ...