from django.db.migrations.exceptions import CircularDependencyError, NodeNotFoundError
from django.db.migrations.graph import DummyNode, MigrationGraph, Node
from django.test import SimpleTestCase
class GraphTests(SimpleTestCase):
"""
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
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_a", "0004"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_node(("app_b", "0002"), None)
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"))
# 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")],
)
# Test roots and leaves
self.assertEqual(
graph.root_nodes(),
[("app_a", "0001"), ("app_b", "0001")],
)
self.assertEqual(
graph.leaf_nodes(),
[("app_a", "0004"), ("app_b", "0002")],
)
def test_complex_graph(self):
r"""
Tests a complex dependency graph:
app_a: 0001 <-- 0002 <--- 0003 <-- 0004
\ \ / /
app_b: 0001 <-\ 0002 <-X /
\ \ /
app_c: \ 0001 <-- 0002 <-
"""
# 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_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)
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"))
# 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"),
],
)
# Test roots and leaves
self.assertEqual(
graph.root_nodes(),
[("app_a", "0001"), ("app_b", "0001"), ("app_c", "0001")],
)
self.assertEqual(
graph.leaf_nodes(),
[("app_a", "0004"), ("app_b", "0002"), ("app_c", "0002")],
)
def test_circular_graph(self):
"""
Tests a circular dependency graph.
"""
# 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_node(("app_b", "0002"), 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"))
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"))
# Test whole graph
with self.assertRaises(CircularDependencyError):
graph.ensure_not_cyclic()
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"))
with self.assertRaises(CircularDependencyError):
graph.ensure_not_cyclic()
def test_iterative_dfs(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)
leaf = expected[-1]
forwards_plan = graph.forwards_plan(leaf)
self.assertEqual(expected, forwards_plan)
backwards_plan = graph.backwards_plan(root)
self.assertEqual(expected[::-1], backwards_plan)
def test_iterative_dfs_complexity(self):
"""
In a graph with merge migrations, iterative_dfs() traverses each node
only once even if there are multiple paths leading to it.
"""
n = 50
graph = MigrationGraph()
for i in range(1, n + 1):
graph.add_node(("app_a", str(i)), None)
graph.add_node(("app_b", str(i)), None)
graph.add_node(("app_c", str(i)), None)
for i in range(1, n):
graph.add_dependency(None, ("app_b", str(i)), ("app_a", str(i)))
graph.add_dependency(None, ("app_c", str(i)), ("app_a", str(i)))
graph.add_dependency(None, ("app_a", str(i + 1)), ("app_b", str(i)))
graph.add_dependency(None, ("app_a", str(i + 1)), ("app_c", str(i)))
plan = graph.forwards_plan(("app_a", str(n)))
expected = [
(app, str(i)) for i in range(1, n) for app in ["app_a", "app_c", "app_b"]
] + [("app_a", str(n))]
self.assertEqual(plan, expected)
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"
with self.assertRaisesMessage(NodeNotFoundError, message):
graph.forwards_plan(("app_b", "0001"))
with self.assertRaisesMessage(NodeNotFoundError, message):
graph.backwards_plan(("app_b", "0001"))
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"))
msg = (
"Migration app_a.0001 dependencies reference nonexistent parent node "
"('app_b', '0002')"
)
with self.assertRaisesMessage(NodeNotFoundError, msg):
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)
msg = (
"Migration app_a.0002 dependencies reference nonexistent child node "
"('app_a', '0002')"
)
with self.assertRaisesMessage(NodeNotFoundError, msg):
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
def test_validate_consistency_missing_parent(self):
graph = MigrationGraph()
graph.add_node(("app_a", "0001"), None)
graph.add_dependency(
"app_a.0001", ("app_a", "0001"), ("app_b", "0002"), skip_validation=True
)
msg = (
"Migration app_a.0001 dependencies reference nonexistent parent node "
"('app_b', '0002')"
)
with self.assertRaisesMessage(NodeNotFoundError, msg):
graph.validate_consistency()
def test_validate_consistency_missing_child(self):
graph = MigrationGraph()
graph.add_node(("app_b", "0002"), None)
graph.add_dependency(
"app_b.0002", ("app_a", "0001"), ("app_b", "0002"), skip_validation=True
)
msg = (
"Migration app_b.0002 dependencies reference nonexistent child node "
"('app_a', '0001')"
)
with self.assertRaisesMessage(NodeNotFoundError, msg):
graph.validate_consistency()
def test_validate_consistency_no_error(self):
graph = MigrationGraph()
graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_b", "0002"), None)
graph.add_dependency(
"app_a.0001", ("app_a", "0001"), ("app_b", "0002"), skip_validation=True
)
graph.validate_consistency()
def test_validate_consistency_dummy(self):
"""
validate_consistency() raises an error if there's an isolated dummy
node.
"""
msg = "app_a.0001 (req'd by app_b.0002) is missing!"
graph = MigrationGraph()
graph.add_dummy_node(
key=("app_a", "0001"), origin="app_b.0002", error_message=msg
)
with self.assertRaisesMessage(NodeNotFoundError, msg):
graph.validate_consistency()
def test_remove_replaced_nodes(self):
"""
Replaced nodes are properly removed and dependencies remapped.
"""
# Add some dummy nodes to be replaced.
graph = MigrationGraph()
graph.add_dummy_node(
key=("app_a", "0001"), origin="app_a.0002", error_message="BAD!"
)
graph.add_dummy_node(
key=("app_a", "0002"), origin="app_b.0001", error_message="BAD!"
)
graph.add_dependency(
"app_a.0002", ("app_a", "0002"), ("app_a", "0001"), skip_validation=True
)
# Add some normal parent and child nodes to test dependency remapping.
graph.add_node(("app_c", "0001"), None)
graph.add_node(("app_b", "0001"), None)
graph.add_dependency(
"app_a.0001", ("app_a", "0001"), ("app_c", "0001"), skip_validation=True
)
graph.add_dependency(
"app_b.0001", ("app_b", "0001"), ("app_a", "0002"), skip_validation=True
)
# Try replacing before replacement node exists.
msg = (
"Unable to find replacement node ('app_a', '0001_squashed_0002'). It was "
"either never added to the migration graph, or has been removed."
)
with self.assertRaisesMessage(NodeNotFoundError, msg):
graph.remove_replaced_nodes(
replacement=("app_a", "0001_squashed_0002"),
replaced=[("app_a", "0001"), ("app_a", "0002")],
)
graph.add_node(("app_a", "0001_squashed_0002"), None)
# Ensure `validate_consistency()` still raises an error at this stage.
with self.assertRaisesMessage(NodeNotFoundError, "BAD!"):
graph.validate_consistency()
# Remove the dummy nodes.
graph.remove_replaced_nodes(
replacement=("app_a", "0001_squashed_0002"),
replaced=[("app_a", "0001"), ("app_a", "0002")],
)
# Ensure graph is now consistent and dependencies have been remapped
graph.validate_consistency()
parent_node = graph.node_map[("app_c", "0001")]
replacement_node = graph.node_map[("app_a", "0001_squashed_0002")]
child_node = graph.node_map[("app_b", "0001")]
self.assertIn(parent_node, replacement_node.parents)
self.assertIn(replacement_node, parent_node.children)
self.assertIn(child_node, replacement_node.children)
self.assertIn(replacement_node, child_node.parents)
def test_remove_replacement_node(self):
"""
A replacement node is properly removed and child dependencies remapped.
We assume parent dependencies are already correct.
"""
# Add some dummy nodes to be replaced.
graph = MigrationGraph()
graph.add_node(("app_a", "0001"), None)
graph.add_node(("app_a", "0002"), None)
graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
# Try removing replacement node before replacement node exists.
msg = (
"Unable to remove replacement node ('app_a', '0001_squashed_0002'). It was"
" either never added to the migration graph, or has been removed already."
)
with self.assertRaisesMessage(NodeNotFoundError, msg):
graph.remove_replacement_node(
replacement=("app_a", "0001_squashed_0002"),
replaced=[("app_a", "0001"), ("app_a", "0002")],
)
graph.add_node(("app_a", "0001_squashed_0002"), None)
# Add a child node to test dependency remapping.
graph.add_node(("app_b", "0001"), None)
graph.add_dependency(
"app_b.0001", ("app_b", "0001"), ("app_a", "0001_squashed_0002")
)
# Remove the replacement node.
graph.remove_replacement_node(
replacement=("app_a", "0001_squashed_0002"),
replaced=[("app_a", "0001"), ("app_a", "0002")],
)
# Ensure graph is consistent and child dependency has been remapped
graph.validate_consistency()
replaced_node = graph.node_map[("app_a", "0002")]
child_node = graph.node_map[("app_b", "0001")]
self.assertIn(child_node, replaced_node.children)
self.assertIn(replaced_node, child_node.parents)
# Child dependency hasn't also gotten remapped to the other replaced
# node.
other_replaced_node = graph.node_map[("app_a", "0001")]
self.assertNotIn(child_node, other_replaced_node.children)
self.assertNotIn(other_replaced_node, child_node.parents)
def test_infinite_loop(self):
"""
Tests a complex dependency graph:
app_a: 0001 <-
\
app_b: 0001 <- x 0002 <-
/ \
app_c: 0001<- <------------- x 0002
And apply squashing on app_c.
"""
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.ensure_not_cyclic()
def test_stringify(self):
graph = MigrationGraph()
self.assertEqual(str(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(str(graph), "Graph: 5 nodes, 3 edges")
self.assertEqual(repr(graph), "<MigrationGraph: nodes=5, edges=3>")
class NodeTests(SimpleTestCase):
def test_node_repr(self):
node = Node(("app_a", "0001"))
self.assertEqual(repr(node), "<Node: ('app_a', '0001')>")
def test_node_str(self):
node = Node(("app_a", "0001"))
self.assertEqual(str(node), "('app_a', '0001')")
def test_dummynode_repr(self):
node = DummyNode(
key=("app_a", "0001"),
origin="app_a.0001",
error_message="x is missing",
)
self.assertEqual(repr(node), "<DummyNode: ('app_a', '0001')>")