def load_pip_requirements(self, files_map=None, freeze=True):
        if files_map is None:
            files_map = self.default_pip_files
        for group, requirements_txt in files_map.items():
            path = Path(requirements_txt)
            if not path.exists() and group.lower() == "all" and freeze:
                cmd = envoy.run("pip freeze")
                self[group].loads(cmd.std_out)
            elif path.exists():
                self[group].load(path)
def test_mirror_formula():
    u, v, f = symbols('u, v, f')
    assert mirror_formula(focal_length=f, u=u) == f*u/(-f + u)
    assert mirror_formula(focal_length=f, v=v) == f*v/(-f + v)
    assert mirror_formula(u=u, v=v) == u*v/(u + v)
    assert mirror_formula(u=oo, v=v) == v
    assert mirror_formula(u=oo, v=oo) is oo
    assert mirror_formula(focal_length=oo, u=u) == -u
    assert mirror_formula(u=u, v=oo) == u
    assert mirror_formula(focal_length=oo, v=oo) is oo
    assert mirror_formula(focal_length=f, v=oo) == f
    assert mirror_formula(focal_length=oo, v=v) == -v
    assert mirror_formula(focal_length=oo, u=oo) is oo
    assert mirror_formula(focal_length=f, u=oo) == f
    assert mirror_formula(focal_length=oo, u=u) == -u
    raises(ValueError, lambda: mirror_formula(focal_length=f, u=u, v=v))