Not able to mock urllib2.urlopen using Python's mock.patch

Below is a code snippet of my api.py module

# -*- coding: utf-8 -*-

from urllib2 import urlopen
from urllib2 import Request

class API:

    def call_api(self, url, post_data=None, header=None):
        is_post_request = True if (post_data and header) else False
        response = None
        try:
            if is_post_request:
                url = Request(url = url, data = post_data, headers = header)
            # Calling api
            api_response = urlopen(url)
            response = api_response.read()
        except Exception as err:
            response = err

        return response

I am trying to mock urllib2.urlopen in unittest of above module. I have written

# -*- coding: utf-8 -*-
# test_api.py

from unittest import TestCase
import mock

from api import API

class TestAPI(TestCase):

    @mock.patch('urllib2.Request')
    @mock.patch('urllib2.urlopen')
    def test_call_api(self, urlopen, Request):
        urlopen.read.return_value = 'mocked'
        Request.get_host.return_value = 'google.com'
        Request.type.return_value = 'https'
        Request.data = {}
        _api = API()
        _api.call_api('https://google.com')

After I run the unittest, I get an exception

<urlopen error unknown url type: <MagicMock name='Request().get_type()' id='159846220'>>

What am I missing? Please help me out.