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Code Issues 32 Releases Wiki Activity

Fixed bug in circular dependency algo for migration dependencies.

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Previous algo only worked if the first item was a part of the loop,
and you would get an infinite loop otherwise (see test).

To fix this, it was much easier to do a pre-pass.

A bonus is that you now get an error message that actually helps you debug
the dependency problem.
This commit is contained in:
Luke Plant
2014-11-25 13:29:38 +00:00
parent 056a3c6c37
commit ff3d746e8d
2 changed files with 35 additions and 10 deletions
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14
tests/migrations/test_graph.py
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@@ -134,6 +134,20 @@ class GraphTests(TestCase):
graph.forwards_plan, ("app_a", "0003"),
)
def test_circular_graph_2(self):
graph = MigrationGraph()
graph.add_node(('A', '0001'), None)
graph.add_node(('C', '0001'), None)
graph.add_node(('B', '0001'), None)
graph.add_dependency('A.0001', ('A', '0001'),('B', '0001'))
graph.add_dependency('B.0001', ('B', '0001'),('A', '0001'))
graph.add_dependency('C.0001', ('C', '0001'),('B', '0001'))
self.assertRaises(
CircularDependencyError,
graph.forwards_plan, ('C', '0001')
)
def test_dfs(self):
graph = MigrationGraph()
root = ("app_a", "1")