def test_is_vacant(db, some_bldg_address, create_some_bldg):
    got = is_vacant(some_bldg_address, db)
    assert got is False

    nothing_there = "g-b(67,37)-l4-b(6512,1298)"
    got = is_vacant(nothing_there, db)
    assert got is True
def test_is_vacant():
    db = MagicMock()
    db.buildings.find_one = MagicMock(return_value=None)
    assert True == is_vacant("g-b(1,2)", db)
    db.buildings.find_one.assert_called_once_with({'address': 'g-b(1,2)'})