def test_it_handles_multiple_edges_to_the_same_node(self):
m1, m2, m3, m4 = self.get_mock_migrations()
m2.depends.add(m1)
m3.depends.add(m1)
m4.depends.add(m1)
assert list(topological_sort([m1, m2, m3, m4])) == [m1, m2, m3, m4]
def test_it_catches_cycles(self):
m1, m2, m3, m4 = self.get_mock_migrations()
m3.depends.add(m3)
with pytest.raises(exceptions.BadMigration):
list(topological_sort([m1, m2, m3, m4]))
def test_it_discards_missing_dependencies(self):
m1, m2, m3, m4 = self.get_mock_migrations()
m3.depends.add(Mock())
assert list(topological_sort([m1, m2, m3, m4])) == [m1, m2, m3, m4]
def test_it_brings_depended_upon_migrations_to_the_front(self):
m1, m2, m3, m4 = self.get_mock_migrations()
m1.depends.add(m4)
assert list(topological_sort([m1, m2, m3, m4])) == [m4, m1, m2, m3]
def test_it_sorts_topologically(self):
m1, m2, m3, m4 = self.get_mock_migrations()
m3.depends.add(m4)
assert list(topological_sort([m1, m2, m3, m4])) == [m4, m3, m1, m2]
def test_it_keeps_stable_order(self):
m1, m2, m3, m4 = self.get_mock_migrations()
assert list(topological_sort([m1, m2, m3, m4])) == [m1, m2, m3, m4]
assert list(topological_sort([m4, m3, m2, m1])) == [m4, m3, m2, m1]
