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django/tests/migrations/test_graph.py

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Fixed #24366 -- Optimized traversal of large migration dependency graphs. Switched from an adjancency list and uncached, iterative depth-first search to a Node-based design with direct parent/child links and a cached, recursive depth-first search. With this change, calculating a migration plan for a large graph takes several seconds instead of several hours. Marked test `migrations.test_graph.GraphTests.test_dfs` as an expected failure due to reaching the maximum recursion depth.
2015-02-20 12:43:45 +08:00
from unittest import expectedFailure
Sorted imports with isort; refs #23860.
2015-01-28 20:35:27 +08:00
from django.db.migrations.graph import (
CircularDependencyError, MigrationGraph, NodeNotFoundError,
)
Start adding operations that work and tests for them
2013-05-30 00:47:10 +08:00
from django.test import TestCase
Fixed #24017 -- Added python_2_unicode_compatible in db/migrations
2014-12-18 07:41:36 +08:00
from django.utils.encoding import force_text
Adding a dependency graph class and tests
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Start adding operations that work and tests for them
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class GraphTests(TestCase):
Adding a dependency graph class and tests
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"""
Tests the digraph structure.
"""
def test_simple_graph(self):
"""
Tests a basic dependency graph:
app_a: 0001 <-- 0002 <--- 0003 <-- 0004
/
app_b: 0001 <-- 0002 <-/
"""
# Build graph
First phase of loading migrations from disk
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graph = MigrationGraph()
Fix graph tests
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graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_a", "0002"), None)
graph.add_node(("app_a", "0003"), None)
graph.add_node(("app_a", "0004"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_node(("app_b", "0002"), None)
Fixed #23341 -- Added migration name to nonexistent migration error in makemigrations.
2014-08-22 15:26:06 +08:00
graph.add_dependency("app_a.0004", ("app_a", "0004"), ("app_a", "0003"))
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_a", "0002"))
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_b", "0002"))
graph.add_dependency("app_b.0002", ("app_b", "0002"), ("app_b", "0001"))
Adding a dependency graph class and tests
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# Test root migration case
self.assertEqual(
graph.forwards_plan(("app_a", "0001")),
[('app_a', '0001')],
)
# Test branch B only
self.assertEqual(
graph.forwards_plan(("app_b", "0002")),
[("app_b", "0001"), ("app_b", "0002")],
)
# Test whole graph
self.assertEqual(
graph.forwards_plan(("app_a", "0004")),
[('app_b', '0001'), ('app_b', '0002'), ('app_a', '0001'), ('app_a', '0002'), ('app_a', '0003'), ('app_a', '0004')],
)
# Test reverse to b:0002
self.assertEqual(
graph.backwards_plan(("app_b", "0002")),
[('app_a', '0004'), ('app_a', '0003'), ('app_b', '0002')],
)
Add root_node and leaf_node functions to MigrationGraph
2013-05-10 23:09:57 +08:00
# Test roots and leaves
self.assertEqual(
graph.root_nodes(),
Fixed #22861: Internal migrations done first so __first__ works Thanks to Chris Beaven.
2014-06-18 14:27:03 +08:00
[('app_a', '0001'), ('app_b', '0001')],
Add root_node and leaf_node functions to MigrationGraph
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)
self.assertEqual(
graph.leaf_nodes(),
Fixed #22861: Internal migrations done first so __first__ works Thanks to Chris Beaven.
2014-06-18 14:27:03 +08:00
[('app_a', '0004'), ('app_b', '0002')],
Add root_node and leaf_node functions to MigrationGraph
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)
Adding a dependency graph class and tests
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def test_complex_graph(self):
"""
Tests a complex dependency graph:
app_a: 0001 <-- 0002 <--- 0003 <-- 0004
\ \ / /
app_b: 0001 <-\ 0002 <-X /
\ \ /
app_c: \ 0001 <-- 0002 <-
"""
# Build graph
First phase of loading migrations from disk
2013-05-10 23:00:55 +08:00
graph = MigrationGraph()
Fix graph tests
2013-05-31 00:56:53 +08:00
graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_a", "0002"), None)
graph.add_node(("app_a", "0003"), None)
graph.add_node(("app_a", "0004"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_node(("app_b", "0002"), None)
graph.add_node(("app_c", "0001"), None)
graph.add_node(("app_c", "0002"), None)
Fixed #23341 -- Added migration name to nonexistent migration error in makemigrations.
2014-08-22 15:26:06 +08:00
graph.add_dependency("app_a.0004", ("app_a", "0004"), ("app_a", "0003"))
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_a", "0002"))
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_b", "0002"))
graph.add_dependency("app_b.0002", ("app_b", "0002"), ("app_b", "0001"))
graph.add_dependency("app_a.0004", ("app_a", "0004"), ("app_c", "0002"))
graph.add_dependency("app_c.0002", ("app_c", "0002"), ("app_c", "0001"))
graph.add_dependency("app_c.0001", ("app_c", "0001"), ("app_b", "0001"))
graph.add_dependency("app_c.0002", ("app_c", "0002"), ("app_a", "0002"))
Adding a dependency graph class and tests
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# Test branch C only
self.assertEqual(
graph.forwards_plan(("app_c", "0002")),
[('app_b', '0001'), ('app_c', '0001'), ('app_a', '0001'), ('app_a', '0002'), ('app_c', '0002')],
)
# Test whole graph
self.assertEqual(
graph.forwards_plan(("app_a", "0004")),
[('app_b', '0001'), ('app_c', '0001'), ('app_a', '0001'), ('app_a', '0002'), ('app_c', '0002'), ('app_b', '0002'), ('app_a', '0003'), ('app_a', '0004')],
)
# Test reverse to b:0001
self.assertEqual(
graph.backwards_plan(("app_b", "0001")),
[('app_a', '0004'), ('app_c', '0002'), ('app_c', '0001'), ('app_a', '0003'), ('app_b', '0002'), ('app_b', '0001')],
)
Add root_node and leaf_node functions to MigrationGraph
2013-05-10 23:09:57 +08:00
# Test roots and leaves
self.assertEqual(
graph.root_nodes(),
Fixed #22861: Internal migrations done first so __first__ works Thanks to Chris Beaven.
2014-06-18 14:27:03 +08:00
[('app_a', '0001'), ('app_b', '0001'), ('app_c', '0001')],
Add root_node and leaf_node functions to MigrationGraph
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)
self.assertEqual(
graph.leaf_nodes(),
Fixed #22861: Internal migrations done first so __first__ works Thanks to Chris Beaven.
2014-06-18 14:27:03 +08:00
[('app_a', '0004'), ('app_b', '0002'), ('app_c', '0002')],
Add root_node and leaf_node functions to MigrationGraph
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)
Adding a dependency graph class and tests
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def test_circular_graph(self):
"""
Tests a circular dependency graph.
"""
# Build graph
First phase of loading migrations from disk
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graph = MigrationGraph()
Fix graph tests
2013-05-31 00:56:53 +08:00
graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_a", "0002"), None)
graph.add_node(("app_a", "0003"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_node(("app_b", "0002"), None)
Fixed #23341 -- Added migration name to nonexistent migration error in makemigrations.
2014-08-22 15:26:06 +08:00
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_a", "0002"))
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
graph.add_dependency("app_a.0001", ("app_a", "0001"), ("app_b", "0002"))
graph.add_dependency("app_b.0002", ("app_b", "0002"), ("app_b", "0001"))
graph.add_dependency("app_b.0001", ("app_b", "0001"), ("app_a", "0003"))
Adding a dependency graph class and tests
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# Test whole graph
self.assertRaises(
First phase of loading migrations from disk
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CircularDependencyError,
Adding a dependency graph class and tests
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graph.forwards_plan, ("app_a", "0003"),
)
Fixed #23352 -- Added tests for MigrationGraph.{forwards,backwards}_plan
2014-08-23 17:37:25 +08:00
Fixed bug in circular dependency algo for migration dependencies. 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.
2014-11-25 21:29:38 +08:00
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)
Fixed flake8 warnings.
2014-11-26 00:20:40 +08:00
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'))
Fixed bug in circular dependency algo for migration dependencies. 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.
2014-11-25 21:29:38 +08:00
self.assertRaises(
CircularDependencyError,
graph.forwards_plan, ('C', '0001')
)
Fixed #24366 -- Optimized traversal of large migration dependency graphs. Switched from an adjancency list and uncached, iterative depth-first search to a Node-based design with direct parent/child links and a cached, recursive depth-first search. With this change, calculating a migration plan for a large graph takes several seconds instead of several hours. Marked test `migrations.test_graph.GraphTests.test_dfs` as an expected failure due to reaching the maximum recursion depth.
2015-02-20 12:43:45 +08:00
def test_deep_graph(self):
graph = MigrationGraph()
root = ("app_a", "1")
graph.add_node(root, None)
expected = [root]
for i in range(2, 750):
parent = ("app_a", str(i - 1))
child = ("app_a", str(i))
graph.add_node(child, None)
graph.add_dependency(str(i), child, parent)
expected.append(child)
actual = graph.node_map[root].descendants()
self.assertEqual(expected[::-1], actual)
@expectedFailure
def test_recursion_depth(self):
switch out recursive dfs for stack based approach, to avoid possibly hitting the recursion limit
2014-09-06 06:26:05 +08:00
graph = MigrationGraph()
root = ("app_a", "1")
graph.add_node(root, None)
expected = [root]
Fix Python 3 incompatability
2014-09-06 06:47:20 +08:00
for i in range(2, 1000):
switch out recursive dfs for stack based approach, to avoid possibly hitting the recursion limit
2014-09-06 06:26:05 +08:00
parent = ("app_a", str(i - 1))
child = ("app_a", str(i))
graph.add_node(child, None)
graph.add_dependency(str(i), child, parent)
expected.append(child)
Fixed #24366 -- Optimized traversal of large migration dependency graphs. Switched from an adjancency list and uncached, iterative depth-first search to a Node-based design with direct parent/child links and a cached, recursive depth-first search. With this change, calculating a migration plan for a large graph takes several seconds instead of several hours. Marked test `migrations.test_graph.GraphTests.test_dfs` as an expected failure due to reaching the maximum recursion depth.
2015-02-20 12:43:45 +08:00
actual = graph.node_map[root].descendants()
switch out recursive dfs for stack based approach, to avoid possibly hitting the recursion limit
2014-09-06 06:26:05 +08:00
self.assertEqual(expected[::-1], actual)
Fixed #23352 -- Added tests for MigrationGraph.{forwards,backwards}_plan
2014-08-23 17:37:25 +08:00
def test_plan_invalid_node(self):
"""
Tests for forwards/backwards_plan of nonexistent node.
"""
graph = MigrationGraph()
message = "Node ('app_b', '0001') not a valid node"
Fixed #23556 -- Raised a more meaningful error message when migrations refer to an unavailable node
2014-09-26 06:24:17 +08:00
with self.assertRaisesMessage(NodeNotFoundError, message):
Fixed #23352 -- Added tests for MigrationGraph.{forwards,backwards}_plan
2014-08-23 17:37:25 +08:00
graph.forwards_plan(("app_b", "0001"))
Fixed #23556 -- Raised a more meaningful error message when migrations refer to an unavailable node
2014-09-26 06:24:17 +08:00
with self.assertRaisesMessage(NodeNotFoundError, message):
Fixed #23352 -- Added tests for MigrationGraph.{forwards,backwards}_plan
2014-08-23 17:37:25 +08:00
graph.backwards_plan(("app_b", "0001"))
Fixed #23341 -- Added migration name to nonexistent migration error in makemigrations.
2014-08-22 15:26:06 +08:00
def test_missing_parent_nodes(self):
"""
Tests for missing parent nodes.
"""
# Build graph
graph = MigrationGraph()
graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_a", "0002"), None)
graph.add_node(("app_a", "0003"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_a", "0002"))
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
Corrected grammar in migrations error message.
2014-09-10 21:54:28 +08:00
msg = "Migration app_a.0001 dependencies reference nonexistent parent node ('app_b', '0002')"
Fixed #23556 -- Raised a more meaningful error message when migrations refer to an unavailable node
2014-09-26 06:24:17 +08:00
with self.assertRaisesMessage(NodeNotFoundError, msg):
Fixed #23341 -- Added migration name to nonexistent migration error in makemigrations.
2014-08-22 15:26:06 +08:00
graph.add_dependency("app_a.0001", ("app_a", "0001"), ("app_b", "0002"))
def test_missing_child_nodes(self):
"""
Tests for missing child nodes.
"""
# Build graph
graph = MigrationGraph()
graph.add_node(("app_a", "0001"), None)
Corrected grammar in migrations error message.
2014-09-10 21:54:28 +08:00
msg = "Migration app_a.0002 dependencies reference nonexistent child node ('app_a', '0002')"
Fixed #23556 -- Raised a more meaningful error message when migrations refer to an unavailable node
2014-09-26 06:24:17 +08:00
with self.assertRaisesMessage(NodeNotFoundError, msg):
Fixed #23341 -- Added migration name to nonexistent migration error in makemigrations.
2014-08-22 15:26:06 +08:00
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
Fixed #23835: Changed circular dependency in DFS to be less infinite
2014-11-16 00:37:13 +08:00
def test_infinite_loop(self):
"""
Tests a complex dependency graph:
app_a: 0001 <-
\
app_b: 0001 <- x 0002 <-
/ \
app_c: 0001<- <------------- x 0002
Fixed #24017 -- Added python_2_unicode_compatible in db/migrations
2014-12-18 07:41:36 +08:00
And apply squashing on app_c.
Fixed #23835: Changed circular dependency in DFS to be less infinite
2014-11-16 00:37:13 +08:00
"""
graph = MigrationGraph()
graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_node(("app_b", "0002"), None)
graph.add_node(("app_c", "0001_squashed_0002"), None)
graph.add_dependency("app_b.0001", ("app_b", "0001"), ("app_c", "0001_squashed_0002"))
graph.add_dependency("app_b.0002", ("app_b", "0002"), ("app_a", "0001"))
graph.add_dependency("app_b.0002", ("app_b", "0002"), ("app_b", "0001"))
graph.add_dependency("app_c.0001_squashed_0002", ("app_c", "0001_squashed_0002"), ("app_b", "0002"))
with self.assertRaises(CircularDependencyError):
graph.forwards_plan(("app_c", "0001_squashed_0002"))
Fixed #24017 -- Added python_2_unicode_compatible in db/migrations
2014-12-18 07:41:36 +08:00
def test_stringify(self):
graph = MigrationGraph()
self.assertEqual(force_text(graph), "Graph: 0 nodes, 0 edges")
graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_a", "0002"), None)
graph.add_node(("app_a", "0003"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_node(("app_b", "0002"), None)
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_a", "0002"))
graph.add_dependency("app_a.0003", ("app_a", "0003"), ("app_b", "0002"))
self.assertEqual(force_text(graph), "Graph: 5 nodes, 3 edges")