def install_pip(self, package, save=True, save_dev=False):
        """Installs a pip package.

        :param save: if `True`, pins the package to the Hydrogen requirements
            YAML file.
        :param save_dev: if `True`, pins the package as a development
            dependency to the Hydrogen requirements YAML file.
        :param return: a **single** :class:`Requirement` object, representing
            the installed version of the given package.
        """
        requirement = Requirement.coerce(package)
        click.echo("pip install " + requirement.package)
        cmd = envoy.run("pip install {}".format(str(requirement)))
        if cmd.status_code == 0:
            installed_packages = get_installed_pypackages()
            package = installed_packages[requirement.package]
            requirement.version = "=={}".format(package.version)
            if save:
                self.requirements["all"].add(requirement)
            if save_dev:
                self.requirements["dev"].add(requirement)
            if save or save_dev:
                self.requirements.save()
            return requirement
        else:
            fatal(cmd.std_err)
def test_methods_etc(self):
        mock_session = Mock()
        mock_session.bind = "the bind"

        sess = scoped_session(lambda: mock_session)

        sess.add("add")
        sess.delete("delete")

        sess.get("Cls", 5)

        eq_(sess.bind, "the bind")

        eq_(
            mock_session.mock_calls,
            [
                mock.call.add("add", _warn=True),
                mock.call.delete("delete"),
                mock.call.get(
                    "Cls",
                    5,
                    options=None,
                    populate_existing=False,
                    with_for_update=None,
                    identity_token=None,
                    execution_options=None,
                ),
            ],
        )

        with mock.patch(
            "sqlalchemy.orm.session.object_session"
        ) as mock_object_session:
            sess.object_session("foo")

        eq_(mock_object_session.mock_calls, [mock.call("foo")])