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_bad_urls():
    values = [
        'foo',
        'http://',
        'http://example',
        'http://example.',
        'http://.com',
        'http://invalid-.com',
        'http://-invalid.com',
        'http://inv-.alid-.com',
        'http://inv-.-alid.com',
        'foo bar baz',
        u'foo \u2713',
        'http://@foo:bar@example.com',
        'http://:bar@example.com',
        'http://bar:bar:bar@example.com',
    ]

    for value in values:
        yield check_bad_url_raises, value