How to call pip programatically from Python#

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# Do not import and use main() directly! Using it directly is actively
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# discouraged by pip's maintainers. The name, location and behavior of
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# this function is subject to change, so calling it directly is not
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# portable across different pip versions.
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# In addition, running pip in-process is unsupported and unsafe. This is
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# elaborated in detail at
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# https://pip.pypa.io/en/stable/user_guide/#using-pip-from-your-program.
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# That document also provides suggestions that should work for nearly
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# all users that are considering importing and using main() directly.
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# However, we know that certain users will still want to invoke pip
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# in-process. If you understand and accept the implications of using pip
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# in an unsupported manner, the best approach is to use runpy to avoid
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# depending on the exact location of this entry point.
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# The following example shows how to use runpy to invoke pip in that
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# case:
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#
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#     sys.argv = ["pip", your, args, here]
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#     runpy.run_module("pip", run_name="__main__")
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#
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# Note that this will exit the process after running, unlike a direct
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# call to main. As it is not safe to do any processing after calling
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# main, this should not be an issue in practice.

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 @cli.command()
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 @click.argument("packages", nargs=-1, required=True)
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 def install(packages):
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     "Install Python packages - e.g. Datasette plugins - into the same environment as Datasette"
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     sys.argv = ["pip", "install"] + list(packages)
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     run_module("pip", run_name="__main__")

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@mock.patch("datasette.cli.run_module")
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def test_install(run_module):
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    runner = CliRunner()
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    runner.invoke(cli, ["install", "datasette-mock-plugin", "datasette-mock-plugin2"])
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    run_module.assert_called_once_with("pip", run_name="__main__")
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    assert sys.argv == [
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        "pip",
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        "install",
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        "datasette-mock-plugin",
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        "datasette-mock-plugin2",
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    ]