requests.Session to memoize response forcedly, depeding on cachetools library.

forcecachesession.py

import cachetools
import requests


class ForceCacheSession(requests.Session):
    """ Force caching requests.Session

    * Apply `cachetools.Cache` by `mount_cache()` methoud
    * It will cache if the method was GET and status code was 200
    * It will apply `res.from_cache` bool value
    """
    def __init__(self):
        super(ForceCacheSession, self).__init__()
        self.cache = None

    def mount_cache(self, cache):
        self.cache = cache

    def request(self, method, *args, **kwargs):
        k = cachetools.typedkey(*args, **kwargs)
        try:
            res = self.cache[k]
            res.from_cache = True
            return res
        except KeyError:
            pass
        res = super(ForceCacheSession, self).request(method, *args, **kwargs)
        if method == 'GET' and res.status_code == 200:
            try:
                self.cache[k] = res
            except ValueError:
                pass  # Value too large
        res.from_cache = False
        return res

tests.py

import unittest
import responses


class TestForceCacheSession(unittest.TestCase):
    def _makeOne(self):
        import cachetools
        from . import ForceCacheSession
        target = ForceCacheSession()
        target.mount_cache(cachetools.Cache(maxsize=1))
        return target

    @responses.activate
    def test__it(self):
        responses.add(responses.GET, 'http://example.com/',
                      status=200, body="Hello")
        target = self._makeOne()
        actual = target.get('http://example.com/')
        self.assertEqual(actual.text, 'Hello')
        self.assertFalse(actual.from_cache)
        actual = target.get('http://example.com/')
        self.assertEqual(actual.text, 'Hello')
        self.assertTrue(actual.from_cache)

    @responses.activate
    def test__not_get(self):
        responses.add(responses.POST, 'http://example.com/',
                      status=200, body="Hello")
        target = self._makeOne()
        actual = target.post('http://example.com/')
        self.assertEqual(actual.text, 'Hello')
        self.assertFalse(actual.from_cache)
        actual = target.post('http://example.com/')
        self.assertEqual(actual.text, 'Hello')
        self.assertFalse(actual.from_cache)

    @responses.activate
    def test__not_200(self):
        responses.add(responses.GET, 'http://example.com/',
                      status=400, body="Hello")
        target = self._makeOne()
        actual = target.get('http://example.com/')
        self.assertEqual(actual.text, 'Hello')
        self.assertFalse(actual.from_cache)
        actual = target.get('http://example.com/')
        self.assertEqual(actual.text, 'Hello')
        self.assertFalse(actual.from_cache)