Fix environment

[frostming]

Fix several issues related to environment:

• Fixes Can't uninstall editable packages even explicitly given to uninstall command #3240
• Fixes 'pipenv clean' fails when running in an existing virtualenv #3231
• Fixes Environment variables not handled in custom scripts #3178

Add a fixture to create and activate a virtualenv out of pipenv.

[techalchemy]

oh boy, this fix looks correct to me. Thanks for handling it

[techalchemy]

You don't like using globals everywhere to figure this out?

[frostming]

Yes the global environment variable is good and convenient but I need a way to get the right status when the environment is modified in runtime.(see the test case)

It isn't a good idea to change the logic only for testing though, because in real case the environment is always decided before any command is launched.

If you are not for this, I can revert these bits and consider using patching in test case.

[techalchemy]

The alternative fixture here is to use pipenv.environment.Environment() which provides a contextmanager called activated:

from pipenv.environment import Environment

@pytest.fixture()
def virtualenv(pathlib_tmpdir, PipenvInstance):
    virtualenv_path = pathlib_tmpdir / "venv"
    with temp_environ():
        c = delegator.run("virtualenv {}".format(virtualenv_path), block=True)
        assert c.return_code == 0
        environment = Environment(prefix=virtualenv_path.as_posix(), is_venv=True, pipfile=PipenvInstance.pipfile)
        with environment.activated():
            yield virtualenv_path

[techalchemy]

P.s. I have no idea if this works

[frostming]

That makes sense for me.

[techalchemy]

Left you a small comment, not sure about the consequences of expanding script variables though, /cc @uranusjr

I'm ok with this if you want to move ahead with your fixture, just wanted to show an alternative

[techalchemy]

P.s. I have no idea if this works

[uranusjr]

At this point I think os.execv (which takes a sequence directly) is better than execl.

[frostming]

Great, let's move on. Thanks guys.