effectivepython/example_code/item_79.py at master · sharc007/effectivepython · GitHub

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#!/usr/bin/env PYTHONHASHSEED=1234 python3

# Licensed under the Apache License, Version 2.0 (the "License");

# you may not use this file except in compliance with the License.

# You may obtain a copy of the License at

# http://www.apache.org/licenses/LICENSE-2.0

# Unless required by applicable law or agreed to in writing, software

# distributed under the License is distributed on an "AS IS" BASIS,

# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

# See the License for the specific language governing permissions and

# limitations under the License.

# Reproduce book environment

import random

random.seed(1234)

import logging

from pprint import pprint

from sys import stdout as STDOUT

# Write all output to a temporary directory

import atexit

import gc

import io

import os

import tempfile

TEST_DIR = tempfile.TemporaryDirectory()

atexit.register(TEST_DIR.cleanup)

# Make sure Windows processes exit cleanly

OLD_CWD = os.getcwd()

atexit.register(lambda: os.chdir(OLD_CWD))

os.chdir(TEST_DIR.name)

def close_open_files():

everything = gc.get_objects()

for obj in everything:

if isinstance(obj, io.IOBase):

obj.close()

atexit.register(close_open_files)

# Example 1

class ZooDatabase:

def get_animals(self, species):

pass

def get_food_period(self, species):

pass

def feed_animal(self, name, when):

pass

# Example 2

from datetime import datetime

def do_rounds(database, species, *, utcnow=datetime.utcnow):

now = utcnow()

feeding_timedelta = database.get_food_period(species)

animals = database.get_animals(species)

fed = 0

for name, last_mealtime in animals:

if (now - last_mealtime) >= feeding_timedelta:

database.feed_animal(name, now)

fed += 1

return fed

# Example 3

from unittest.mock import Mock

database = Mock(spec=ZooDatabase)

print(database.feed_animal)

database.feed_animal()

database.feed_animal.assert_any_call()

# Example 4

from datetime import timedelta

from unittest.mock import call

now_func = Mock(spec=datetime.utcnow)

now_func.return_value = datetime(2019, 6, 5, 15, 45)

database = Mock(spec=ZooDatabase)

database.get_food_period.return_value = timedelta(hours=3)

database.get_animals.return_value = [

('Spot', datetime(2019, 6, 5, 11, 15)),

('Fluffy', datetime(2019, 6, 5, 12, 30)),

('Jojo', datetime(2019, 6, 5, 12, 55))

]

# Example 5

result = do_rounds(database, 'Meerkat', utcnow=now_func)

assert result == 2

database.get_food_period.assert_called_once_with('Meerkat')

database.get_animals.assert_called_once_with('Meerkat')

database.feed_animal.assert_has_calls(

[

call('Spot', now_func.return_value),

call('Fluffy', now_func.return_value),

any_order=True)

# Example 6

try:

database.bad_method_name()

except:

logging.exception('Expected')

else:

assert False

# Example 7

DATABASE = None

def get_database():

global DATABASE

if DATABASE is None:

DATABASE = ZooDatabase()

return DATABASE

def main(argv):

database = get_database()

species = argv[1]

count = do_rounds(database, species)

print(f'Fed {count} {species}(s)')

return 0

# Example 8

import contextlib

import io

from unittest.mock import patch

with patch('__main__.DATABASE', spec=ZooDatabase):

now = datetime.utcnow()

DATABASE.get_food_period.return_value = timedelta(hours=3)

DATABASE.get_animals.return_value = [

('Spot', now - timedelta(minutes=4.5)),

('Fluffy', now - timedelta(hours=3.25)),

('Jojo', now - timedelta(hours=3)),

]

fake_stdout = io.StringIO()

with contextlib.redirect_stdout(fake_stdout):

main(['program name', 'Meerkat'])

found = fake_stdout.getvalue()

expected = 'Fed 2 Meerkat(s)\n'

assert found == expected

effectivepython/example_code/item_79.py at master · sharc007/effectivepython · GitHub

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