def test_fork(self):
"Test that a forked graph works"
graph = {1: [], 2: [1], 3: [1], 4: [2, 3]} # type: Dict[int, List[int]]
# Valid orderings are `[1, 3, 2, 4]` or `[1, 2, 3, 4]`, but we should
# always get the same one.
self.assertEqual(list(sorted_topologically([4, 3, 2, 1], graph)), [1, 2, 3, 4])
def test_disconnected(self):
"Test that a graph with no edges work"
graph = {1: [], 2: []} # type: Dict[int, List[int]]
# For disconnected nodes the output is simply sorted.
self.assertEqual(list(sorted_topologically([1, 2], graph)), [1, 2])
def test_handle_empty_graph(self):
"Test that a graph where a node doesn't have an entry is treated as empty"
graph = {} # type: Dict[int, List[int]]
# For disconnected nodes the output is simply sorted.
self.assertEqual(list(sorted_topologically([1, 2], graph)), [1, 2])
def test_linear(self):
"Test that a simple `4 -> 3 -> 2 -> 1` graph works"
graph = {1: [], 2: [1], 3: [2], 4: [3]} # type: Dict[int, List[int]]
self.assertEqual(list(sorted_topologically([4, 3, 2, 1], graph)),
[1, 2, 3, 4])
def test_multiple_paths(self):
"Test that a graph with multiple paths between two nodes work"
graph = {
1: [],
2: [1],
3: [2],
4: [3, 2, 1]
} # type: Dict[int, List[int]]
self.assertEqual(list(sorted_topologically([4, 3, 2, 1], graph)),
[1, 2, 3, 4])
def test_duplicates(self):
"Test that a graph with duplicate edges work"
graph = {
1: [],
2: [1, 1],
3: [2, 2],
4: [3]
} # type: Dict[int, List[int]]
self.assertEqual(list(sorted_topologically([4, 3, 2, 1], graph)),
[1, 2, 3, 4])
def test_subset(self):
"Test that only sorting a subset of the graph works"
graph = {1: [], 2: [1], 3: [2], 4: [3]} # type: Dict[int, List[int]]
self.assertEqual(list(sorted_topologically([4, 3], graph)), [3, 4])
def test_empty(self):
"Test that an empty graph works correctly"
graph = {} # type: Dict[int, List[int]]
self.assertEqual(list(sorted_topologically([], graph)), [])
