def METHOD_NAME(pipenv_instance_pypi):
    with pipenv_instance_pypi() as p:
        with open(p.pipfile_path, "w") as f:
            contents = """
        [packages]
        pytest = "==4.6.11"
        [dev-packages]
        six = "*"
        """
            f.write(contents)
        c = p.pipenv("install")
        assert c.returncode == 0
        c = p.pipenv("uninstall --all-dev")
        assert c.returncode == 0
        assert "six" in p.lockfile["default"]