test_models.py

from botocore import Stubber, ANY
import pytest
import models

@pytest.fixture(scope="function")
def ddb_stubber():
    ddb_stubber = Stubber(models.Table.meta.client)
    ddb_stubber.activate()
    yield ddb_stubber
    ddb_stubber.deactivate()

def test_user_exists(ddb_stubber):
    user_id = 'user123'
    get_item_params = {'TableName': ANY,
                       'Key': {'id': user_id}}
    get_item_response = {'Item': {'id': {'S': user_id},
                                  'name': {'S': 'Spam'}}}
    ddb_stubber.add_response('get_item', get_item_response, get_item_params)

    result = main.get_user(user_id)
    assert result.get('id') == user_id
    ddb_stubber.assert_no_pending_responses()

def test_user_missing(ddb_stubber):
    user_id = 'user123'
    get_item_params = {'TableName': ANY,
                       'Key': {'id': user_id}}
    get_item_response = {}
    ddb_stubber.add_response('get_item', get_item_response, get_item_params)

    result = main.get_user(user_id)
    assert result is None
    ddb_stubber.assert_no_pending_responses()