def test_cache_miss_kwargs(self):
"""
Tests a cache miss against a function with kwargs
"""
mock_client = Mock()
# Simulates a cache miss
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = ''
# Create a function with the decorator
@redis_cache.cache(invalidator=True)
def test_function(a, b, c=None, d=None):
return a
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(test_function, args, kwargs)
# Call that function
test_a = 'input'
test_b = 'b'
test_c = True
test_d = False
function_response, invalidator \
= test_function(test_a, test_b, c=test_c, d=test_d)
expected_hash = cache_key_for(test_a, test_b, c=test_c, d=test_d)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
redis_cache.backend.set_cache_and_expire.assert_called_once_with(
expected_hash, pickle.dumps(test_a), DEFAULT_EXPIRATION)
# Call the cache invalidator
invalidator()
mock_client.invalidate_key.assert_called_once_with(expected_hash)
def test_cache_miss_expiration(self):
"""
Tests a cache miss with an expiration given
"""
test_param = 'cache hit test'
ttl = 100
mock_client = Mock()
# Simulates a cache hit
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = ''
# Create a function with the decorator
@redis_cache.cache(expiration=ttl)
def test_function(a):
return a
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(test_function, args, kwargs)
# Call that function
function_response = test_function(test_param)
expected_hash = cache_key_for(test_param)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
redis_cache.backend.set_cache_and_expire.assert_called_once_with(
expected_hash, pickle.dumps(test_param), ttl)
self.assertEqual(redis_cache.backend.set_cache.call_count, 0)
def test_simple_object_pickle(self):
"""
Tests caching of a simple Python object with pickling
"""
mock_client = Mock()
# Simulates a cache miss
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = ''
# Create a function with the decorator
simple_obj = SimpleObject('test', 42)
@redis_cache.cache()
def test_function(a):
return simple_obj
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(test_function, args, kwargs)
# Call that function
test_param = 'input'
function_response = test_function(test_param)
self.assertEqual(function_response, simple_obj)
expected_hash = cache_key_for(test_param)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
redis_cache.backend.set_cache_and_expire.assert_called_once_with(
expected_hash, pickle.dumps(simple_obj), DEFAULT_EXPIRATION)
# Call that function, again, expecting a cache hit
redis_cache.backend.get_cache.return_value = pickle.dumps(simple_obj)
function_response = test_function(test_param)
self.assertEqual(function_response, simple_obj)
def test_simple_object(self):
"""
Tests that the cache uses an object's __str__ method to generate
the signature of an object if available
"""
mock_client = Mock()
# Simulates a cache miss
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = ''
class TestClass(object):
def __init__(self, parameter):
self.parameter = parameter
@redis_cache.cache()
def cache_this_method(self):
return self.parameter
def __str__(self):
return "<TestClass object: parameter=%s>" % self.parameter
def cache_key_for(arg):
fn = TestClass.cache_this_method
args = [TestClass(arg)]
return redis_cache._generate_cache_key(fn, args)
param = 'some_param'
test_class = TestClass(param)
test_class.cache_this_method()
expected_hash = cache_key_for(param)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
def test_cache_miss(self):
"""
Tests a cache miss
"""
mock_client = Mock()
# Simulates a cache miss
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = ''
# Create a function with the decorator
@redis_cache.cache()
def test_function(a):
return a
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(test_function, args, kwargs)
# Call that function
test_param = 'input'
function_response = test_function(test_param)
expected_hash = cache_key_for(test_param)
mock_client.get_cache.assert_called_once_with(expected_hash)
mock_client.set_cache_and_expire.assert_called_once_with(
expected_hash, pickle.dumps(test_param), DEFAULT_EXPIRATION)
def test_redis_failure(self):
"""
Tests that the function gets ran as expected when Redis fails
"""
test_param = 'cache hit test'
mock_client = Mock()
# Simulates a cache hit
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.side_effect = BackendException
# Create a function with the decorator
@redis_cache.cache()
def test_function(a):
return a
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(test_function, args, kwargs)
# Call that function
function_response = test_function(test_param)
expected_hash = cache_key_for(test_param)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
self.assertEqual(redis_cache.backend.set_cache.call_count, 0)
self.assertEqual(function_response, test_param)
@redis_cache.cache(invalidator=True)
def test_function(a):
return a
function_response, invalidator = test_function(test_param)
self.assertIsNone(invalidator)
def test_cache_hit_invalidate(self):
"""
Tests a cache hit with invalidation
"""
test_param = 'cache hit test'
mock_client = Mock()
# Simulates a cache hit
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = pickle.dumps(test_param)
# Create a function with the decorator and invalidator param
@redis_cache.cache(invalidator=True)
def test_function(a):
return a
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(test_function, args, kwargs)
# Call that function
function_response, invalidator = test_function(test_param)
expected_hash = cache_key_for(test_param)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
self.assertEqual(redis_cache.backend.set_cache.call_count, 0)
self.assertEqual(function_response, test_param)
# Invalidator should be callable
self.assertTrue(hasattr(invalidator, '__call__'))
# Invalidate the cache
invalidator()
# Cache entry should have been deleted
redis_cache.backend.invalidate_key.assert_called_once_with(
expected_hash)
def test_cache_hit(self):
"""
Tests a cache hit
"""
test_param = 'cache hit test'
mock_client = Mock()
# Simulates a cache hit
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = pickle.dumps(test_param)
# Create a function with the decorator
@redis_cache.cache()
def test_function(a):
return a
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(test_function, args, kwargs)
# Call that function
function_response = test_function(test_param)
expected_hash = cache_key_for(test_param)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
self.assertEqual(redis_cache.backend.set_cache.call_count, 0)
self.assertEqual(function_response, test_param)
def test_cache_on_stateful_class_without_str(self):
"""
Tests that the cache gets populated when invoking a method on an object
that is stateful and that doesn't implement a custom __str__ method.
Some object are stateful, i.e. their methods will return different
values at different times in the object's life-cycle. When the state of
the object changes, we need to make sure that the cache doesn't return
values for the previous state of the object.
"""
mock_client = Mock()
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
class TestClass(object):
def __init__(self, state=None):
self.state = state
@redis_cache.cache()
def some_method(self):
return self.state
def cache_key_for(state):
fn = TestClass.some_method
args = [TestClass(state)]
return redis_cache._generate_cache_key(fn, args)
state1 = 'some simple type state'
state2 = SimpleObject('some complex type state', 123)
def cache_get(cache_key):
if cache_key == cache_key_for(state1):
return pickle.dumps(state1)
if cache_key == cache_key_for(state2):
return pickle.dumps(state2)
raise ValueError('called cache for hash: {}'.format(cache_key))
redis_cache.backend.get_cache.side_effect = cache_get
# call the object in some initial state
stateful_instance = TestClass()
stateful_instance.state = state1
return_value_for_state1 = stateful_instance.some_method()
# mutate the state of the object and make sure that we don't hit the
# cache for the previous state
stateful_instance.state = state2
return_value_for_state2 = stateful_instance.some_method()
self.assertNotEqual(return_value_for_state1, return_value_for_state2)
def test_cache_on_class_without_str(self):
"""
Tests that the cache gets populated when invoking a method that takes a
primitive type as argument on an object that does not implement a custom
__str__ method.
"""
mock_client = Mock()
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
class TestClass(object):
def __init__(self):
self.call_count = collections.defaultdict(int)
@redis_cache.cache()
def echo(self, parameter):
self.call_count[parameter] += 1
return parameter
primitive_argument = 'cache hit test'
complex_argument = SimpleObject('test', 42)
for argument in primitive_argument, complex_argument:
# on the first call, the cache is empty
instance = TestClass()
redis_cache.backend.get_cache.return_value = ''
instance1_return1 = instance.echo(argument)
# after the first call, the cache is set, i.e. all the subsequent
# calls will return the previously computed value from cache
redis_cache.backend.get_cache.return_value = pickle.dumps(argument)
instance1_return2 = instance.echo(argument)
instance1_return3 = instance.echo(argument)
self.assertEqual(instance1_return1, argument)
self.assertEqual(instance1_return2, argument)
self.assertEqual(instance1_return3, argument)
self.assertEqual(instance.call_count[argument], 1)
# the cache should also be hit for calls to the same method on a new
# but equivalent object
equivalent_instance = TestClass()
instance2_return1 = equivalent_instance.echo(argument)
instance2_return2 = equivalent_instance.echo(argument)
self.assertEqual(instance2_return1, argument)
self.assertEqual(instance2_return2, argument)
self.assertEqual(equivalent_instance.call_count[argument], 0)
def test_cache_custom_signature(self):
"""
Tests a cache hit with custom signature
"""
test_param = 'cache hit test'
mock_client = Mock()
# Simulates a cache hit
redis_cache = RedisCache(Backend())
redis_cache.backend = mock_client
redis_cache.backend.get_cache.return_value = pickle.dumps(test_param)
def test_signature_builder(*args, **kwargs):
return "test"
# Create a function with the decorator
@redis_cache.cache(signature_generator=test_signature_builder)
def test_function(a):
return a
def cache_key_for(*args, **kwargs):
return redis_cache._generate_cache_key(
test_function,
args,
kwargs,
signature_generator=test_signature_builder)
# Call that function
function_response = test_function(test_param)
expected_hash = cache_key_for(test_param)
redis_cache.backend.get_cache.assert_called_once_with(expected_hash)
self.assertEqual(redis_cache.backend.set_cache.call_count, 0)
self.assertEqual(function_response, test_param)
# Test that the signature_generator must be callable
@redis_cache.cache(signature_generator='not callable')
def test_function_not_callable(a):
return a
with self.assertRaises(TypeError):
test_function_not_callable(test_param)
