def test_get_should_return_neg1_when_0_capacity(self):
"""
LRU_Cache::get() should return -1 when the cache's capacity is 0.
"""
cache = LRU_Cache(0)
cache.set(1, 1)
self.assertEqual(-1, cache.get(1))
def test_search_cache_nonexistent_data(self):
our_cache = LRU_Cache(5)
our_cache.set(1, 1)
self.assertEqual(-1, our_cache.get(
9)) # returns -1 because 9 is not present in the cache
def test_cache_before_limit(self):
our_cache = LRU_Cache(3)
our_cache.set(1, 1)
our_cache.set(2, 2)
our_cache.set(3, 3)
self.assertEqual(our_cache.curr_oper_capacity, 3)
self.assertEqual(our_cache.get(1), 1)
def test_past_max_capacity(self):
our_cache = LRU_Cache(5)
our_cache.set(1, 1)
our_cache.set(2, 2)
our_cache.set(3, 3)
our_cache.set(4, 4)
our_cache.get(1)
self.assertEqual(our_cache.get(2), 2)
self.assertEqual(our_cache.get(1), -1)
def test_insert_data_in_cache(self):
our_cache = LRU_Cache(5)
our_cache.set(1, 1)
our_cache.set(2, 2)
our_cache.set(3, 3)
our_cache.set(4, 4)
self.assertEqual(1, our_cache.get(1)) # returns 1
self.assertEqual(2, our_cache.get(2)) # returns 2
def test_set_should_return_neg1_when_falsey_key_given(self):
"""
LRU_Cache::set() should return -1 when a falsey key is given.
"""
cache = LRU_Cache(5)
self.assertEqual(-1, cache.set('', 1))
self.assertEqual(-1, cache.set(None, 1))
self.assertEqual(-1, cache.set(False, 1))
self.assertEqual(-1, cache.set([], 1))
self.assertEqual(-1, cache.set({}, 1))
self.assertEqual(0, len(cache.hashtable))
def test_insert_cache_items_added_below_capacity(self):
"""
"""
our_cache = LRU_Cache(5)
our_cache.set(1, 1)
our_cache.set(2, 2)
our_cache.set(3, 3)
our_cache.set(4, 4)
self.assertEqual(4, len(our_cache.cacheStorageMap))
self.assertTrue(our_cache.capacity > len(our_cache.cacheStorageMap))
def test_set_should_return_neg1_when_0_capacity(self):
"""
LRU_Cache::set() should return -1 and not set the value when the cache's capacity is 0.
"""
cache = LRU_Cache(0)
self.assertEqual(-1, cache.set(1, 1))
self.assertEqual(0, len(cache.hashtable))
def test_get_should_return_value_and_move_node_to_front(self):
"""
LRU_Cache::get() should return the value and move the node to the front (MRU) position
of the linked list.
"""
# Set up.
cache = LRU_Cache(5)
test_data = {
'udacity': 1,
'python': 2,
100: 'hello world',
200: 'algorithms'
}
for key, value in test_data.items():
cache.set(key, value)
# Test -1 is returned if the key does not exist.
self.assertEqual(-1, cache.get('does_not_exist'))
# Test getting the value and that the node was moved to the front (MRU) position.
self.assertEqual('hello world', cache.get(100))
node = cache.head.next
self.assertEqual(cache.hashtable[100], node)
self.assertEqual('hello world', node.value)
self.assertEqual(100, node.key)
self.assertEqual(2, cache.get('python'))
node = cache.head.next
self.assertEqual(cache.hashtable['python'], node)
self.assertEqual(2, node.value)
self.assertEqual('python', node.key)
self.assertEqual(1, cache.get('udacity'))
node = cache.head.next
self.assertEqual(cache.hashtable['udacity'], node)
self.assertEqual(1, node.value)
self.assertEqual('udacity', node.key)
self.assertEqual('algorithms', cache.get(200))
node = cache.head.next
self.assertEqual(cache.hashtable[200], node)
self.assertEqual('algorithms', node.value)
self.assertEqual(200, node.key)
# Clean up.
cache.clear()
def test_set_should_cache_the_new_node(self):
"""
LRU_Cache::set() should cache (add) the new node.
"""
# Set up.
cache = LRU_Cache(5)
test_data = {
'udacity': 1,
'python': 2,
100: 'hello world',
200: 'algorithms'
}
# Test set stores each item.
for key, value in test_data.items():
self.assertFalse(key in cache.hashtable)
cache.set(key, value)
self.assertTrue(key in cache.hashtable)
# Test each node in the linked list.
node = cache.head.next
self.assertEqual(cache.hashtable[200], node)
self.assertEqual('algorithms', node.value)
self.assertEqual(200, node.key)
node = node.next
self.assertEqual(cache.hashtable[100], node)
self.assertEqual('hello world', node.value)
self.assertEqual(100, node.key)
node = node.next
self.assertEqual(cache.hashtable['python'], node)
self.assertEqual(2, node.value)
self.assertEqual('python', node.key)
node = node.next
self.assertEqual(cache.hashtable['udacity'], node)
self.assertEqual(1, node.value)
self.assertEqual('udacity', node.key)
# Test the tail node.
self.assertEqual(cache.hashtable['udacity'], cache.tail.prev)
# Clean up.
cache.clear()
def test_set_should_remove_lru_node_when_overcapacity(self):
"""
LRU_Cache::set() should remove the LRU node when overcapacity.
"""
# Set up.
cache = LRU_Cache(4)
test_data = {
'udacity': 1,
'python': 2,
100: 'hello world',
200: 'algorithms'
}
for key, value in test_data.items():
cache.set(key, value)
# Check the before states.
self.assertEqual(cache.hashtable['udacity'], cache.tail.prev)
self.assertEqual(len(cache.hashtable), cache.capacity)
cache.set(300, 'overcapacity')
# Test that the previous last node has been removed.
self.assertEqual(len(cache.hashtable), cache.capacity)
self.assertFalse('udacity' in cache.hashtable)
self.assertEqual(-1, cache.get('udacity'))
self.assertEqual(cache.hashtable['python'], cache.tail.prev)
# Retest each node in the linked list.
node = cache.head.next
self.assertEqual(cache.hashtable[300], node)
self.assertEqual(cache.hashtable[200], node.next)
self.assertEqual(cache.hashtable[100], node.next.next)
self.assertEqual(cache.hashtable['python'], node.next.next.next)
# Clean up.
cache.clear()
def test_insert_data_cache_capacity_exceeded(self):
our_cache = LRU_Cache(5)
our_cache.set(1, 1)
our_cache.set(2, 2)
our_cache.set(3, 3)
our_cache.set(4, 4)
#Move items in the cache, so that they are positioned closer to the top if the recently used list
our_cache.get(1)
our_cache.get(2)
our_cache.set(5, 5)
our_cache.set(6, 6)
self.assertEqual(
our_cache.get(3), -1
) # returns -1 because the cache reached it's capacity and 3 was the least recently used entry
self.assertEqual(list(our_cache.cacheStorageMap.keys()),
[1, 2, 4, 5, 6]) # [1, 2, 4, 5, 6]
def test_invalid_element(self):
our_cache = LRU_Cache(2)
our_cache.set(1, 1)
self.assertEqual(our_cache.get(9), -1)
def test_set_should_overwrite_existing_nodes(self):
"""
LRU_Cache::set() should overwrite existing nodes and move the node to the front (MRU) position
of the linked list.
"""
# Set up.
cache = LRU_Cache(5)
test_data = {
'udacity': 1,
'python': 2,
100: 'hello world',
200: 'algorithms'
}
for key, value in test_data.items():
cache.set(key, value)
#
# Test a node in the middle.
#
# Test set overwrites value in the existing node.
prev_number_items = len(cache.hashtable)
self.assertEqual(2, cache.hashtable['python'].value)
cache.set('python', 20)
self.assertEqual(20, cache.hashtable['python'].value)
self.assertEqual(prev_number_items, len(cache.hashtable))
# Test that the node was moved to the MRU position.
node = cache.head.next
self.assertEqual(cache.hashtable['python'], node)
self.assertEqual(20, node.value)
self.assertEqual('python', node.key)
# Test the wiring in the rest of the linked list.
node = node.next
self.assertEqual(cache.hashtable[200], node)
self.assertEqual('algorithms', node.value)
self.assertEqual(200, node.key)
node = node.next
self.assertEqual(cache.hashtable[100], node)
self.assertEqual('hello world', node.value)
self.assertEqual(100, node.key)
node = node.next
self.assertEqual(cache.hashtable['udacity'], node)
self.assertEqual(1, node.value)
self.assertEqual('udacity', node.key)
self.assertEqual(cache.hashtable['udacity'], cache.tail.prev)
#
# Test the last node.
#
# Test set overwrites value in the existing node.
prev_number_items = len(cache.hashtable)
self.assertEqual(1, cache.hashtable['udacity'].value)
cache.set('udacity', 10)
self.assertEqual(10, cache.hashtable['udacity'].value)
self.assertEqual(prev_number_items, len(cache.hashtable))
# Test that the node was moved to the MRU position.
node = cache.head.next
self.assertEqual(cache.hashtable['udacity'], node)
self.assertEqual(10, node.value)
self.assertEqual('udacity', node.key)
node = node.next
self.assertEqual(cache.hashtable['python'], node)
self.assertEqual(20, node.value)
self.assertEqual('python', node.key)
# Test the wiring in the rest of the linked list.
node = node.next
self.assertEqual(cache.hashtable[200], node)
self.assertEqual('algorithms', node.value)
self.assertEqual(200, node.key)
node = node.next
self.assertEqual(cache.hashtable[100], node)
self.assertEqual('hello world', node.value)
self.assertEqual(100, node.key)
self.assertEqual(cache.hashtable[100], cache.tail.prev)
# Clean up.
cache.clear()