def test_cycle_detection(self):
"""Test public methods on a task set, which forms a cycle."""
a_scheduler = Scheduler()
# Build the dependency graph, which is a cycle:
# A -> B -> C -> A
a_scheduler.add_a_prerequisite(task='A', prerequisite='B')
a_scheduler.add_a_prerequisite(task='B', prerequisite='C')
a_scheduler.add_a_prerequisite(task='C', prerequisite='A')
with self.assertRaises(AssertionError):
a_scheduler.schedule()
def test_multiple_linked_lists(self):
"""Test public methods on a task set, which forms two linked lists."""
a_scheduler = Scheduler()
# Build the first linked list:
# A <- B <- C
a_scheduler.add_a_prerequisite(task='B', prerequisite='A')
a_scheduler.add_a_prerequisite(task='C', prerequisite='B')
# Build the second linked list:
# 1 <- 2 <- 3
a_scheduler.add_a_prerequisite(task=2, prerequisite=1)
a_scheduler.add_a_prerequisite(task=3, prerequisite=2)
# Only one result is correct.
scheduled_tasks = a_scheduler.schedule()
self.assertEqual(scheduled_tasks, {('A', 'B', 'C'), (1, 2, 3)})
def test_binary_tree(self):
"""Test public methods on a task set, which forms a binary tree."""
a_scheduler = Scheduler()
# Build the dependency graph, which is a binary tree:
# A
# / \
# B C
a_scheduler.add_a_prerequisite(task='B', prerequisite='A')
a_scheduler.add_a_prerequisite(task='C', prerequisite='A')
# Two possible results:
# - A must appears before B and C.
# - No requirements on the relative order of B and C.
schedued_tasks = a_scheduler.schedule()
self.assertTrue(schedued_tasks in ({('A', 'B', 'C')}, {('A', 'C',
'B')}))
def test_linked_list(self):
"""Test public methods on a task set, which forms a linked list."""
a_scheduler = Scheduler()
self.assertEqual(a_scheduler.n_tasks(), 0)
a_scheduler.add_a_task('A')
self.assertEqual(a_scheduler.n_tasks(), 1)
a_scheduler.add_a_task('B')
self.assertEqual(a_scheduler.n_tasks(), 2)
a_scheduler.add_a_task('B')
self.assertEqual(a_scheduler.n_tasks(), 2)
a_scheduler.add_tasks(('C', 'D'))
self.assertEqual(a_scheduler.n_tasks(), 4)
# Build the dependency graph, which is a linked list:
# A <- B <- C <- D
a_scheduler.add_a_prerequisite(task='B', prerequisite='A')
a_scheduler.add_a_prerequisite(task='C', prerequisite='B')
a_scheduler.add_a_prerequisite(task='D', prerequisite='C')
# Only one result is correct.
schedued_tasks = a_scheduler.schedule()
self.assertEqual(schedued_tasks, {('A', 'B', 'C', 'D')})
