Fixed #23556 -- Raised a more meaningful error message when migrations refer to an unavailable node

17 files changed, 286 insertions, 5 deletions

diff --git a/tests/migrations/test_graph.py b/tests/migrations/test_graph.py
index 3fcdd12667..e70481a462 100644
--- a/tests/migrations/test_graph.py
+++ b/tests/migrations/test_graph.py
@@ -1,5 +1,5 @@
 from django.test import TestCase
-from django.db.migrations.graph import MigrationGraph, CircularDependencyError
+from django.db.migrations.graph import CircularDependencyError, MigrationGraph, NodeNotFoundError
 
 
 class GraphTests(TestCase):
@@ -156,10 +156,10 @@ class GraphTests(TestCase):
         graph = MigrationGraph()
         message = "Node ('app_b', '0001') not a valid node"
 
-        with self.assertRaisesMessage(ValueError, message):
+        with self.assertRaisesMessage(NodeNotFoundError, message):
             graph.forwards_plan(("app_b", "0001"))
 
-        with self.assertRaisesMessage(ValueError, message):
+        with self.assertRaisesMessage(NodeNotFoundError, message):
             graph.backwards_plan(("app_b", "0001"))
 
     def test_missing_parent_nodes(self):
@@ -175,7 +175,7 @@ class GraphTests(TestCase):
         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(KeyError, msg):
+        with self.assertRaisesMessage(NodeNotFoundError, msg):
             graph.add_dependency("app_a.0001", ("app_a", "0001"), ("app_b", "0002"))
 
     def test_missing_child_nodes(self):
@@ -186,5 +186,5 @@ class GraphTests(TestCase):
         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(KeyError, msg):
+        with self.assertRaisesMessage(NodeNotFoundError, msg):
             graph.add_dependency("app_a.0002", ("app_a", "0002"), ("app_a", "0001"))
diff --git a/tests/migrations/test_loader.py b/tests/migrations/test_loader.py
index 676c843e9d..a921321525 100644
--- a/tests/migrations/test_loader.py
+++ b/tests/migrations/test_loader.py
@@ -1,7 +1,10 @@
+from __future__ import unicode_literals
+
 from unittest import skipIf
 
 from django.test import TestCase, override_settings
 from django.db import connection, connections
+from django.db.migrations.graph import NodeNotFoundError
 from django.db.migrations.loader import MigrationLoader, AmbiguityError
 from django.db.migrations.recorder import MigrationRecorder
 from django.test import modify_settings
@@ -187,3 +190,104 @@ class LoaderTests(TestCase):
             2,
         )
         recorder.flush()
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_squashed_complex"})
+    def test_loading_squashed_complex(self):
+        "Tests loading a complex set of squashed migrations"
+
+        loader = MigrationLoader(connection)
+        recorder = MigrationRecorder(connection)
+
+        def num_nodes():
+            plan = set(loader.graph.forwards_plan(('migrations', '7_auto')))
+            return len(plan - loader.applied_migrations)
+
+        # Empty database: use squashed migration
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 5)
+
+        # Starting at 1 or 2 should use the squashed migration too
+        recorder.record_applied("migrations", "1_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 4)
+
+        recorder.record_applied("migrations", "2_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 3)
+
+        # However, starting at 3 to 5 cannot use the squashed migration
+        recorder.record_applied("migrations", "3_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 4)
+
+        recorder.record_applied("migrations", "4_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 3)
+
+        # Starting at 5 to 7 we are passed the squashed migrations
+        recorder.record_applied("migrations", "5_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 2)
+
+        recorder.record_applied("migrations", "6_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 1)
+
+        recorder.record_applied("migrations", "7_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 0)
+
+        recorder.flush()
+
+    @override_settings(MIGRATION_MODULES={"migrations": "migrations.test_migrations_squashed_erroneous"})
+    def test_loading_squashed_erroneous(self):
+        "Tests loading a complex but erroneous set of squashed migrations"
+
+        loader = MigrationLoader(connection)
+        recorder = MigrationRecorder(connection)
+
+        def num_nodes():
+            plan = set(loader.graph.forwards_plan(('migrations', '7_auto')))
+            return len(plan - loader.applied_migrations)
+
+        # Empty database: use squashed migration
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 5)
+
+        # Starting at 1 or 2 should use the squashed migration too
+        recorder.record_applied("migrations", "1_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 4)
+
+        recorder.record_applied("migrations", "2_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 3)
+
+        # However, starting at 3 or 4 we'd need to use non-existing migrations
+        msg = ("Migration migrations.6_auto depends on nonexistent node ('migrations', '5_auto'). "
+               "Django tried to replace migration migrations.5_auto with any of "
+               "[migrations.3_squashed_5] but wasn't able to because some of the replaced "
+               "migrations are already applied.")
+
+        recorder.record_applied("migrations", "3_auto")
+        with self.assertRaisesMessage(NodeNotFoundError, msg):
+            loader.build_graph()
+
+        recorder.record_applied("migrations", "4_auto")
+        with self.assertRaisesMessage(NodeNotFoundError, msg):
+            loader.build_graph()
+
+        # Starting at 5 to 7 we are passed the squashed migrations
+        recorder.record_applied("migrations", "5_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 2)
+
+        recorder.record_applied("migrations", "6_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 1)
+
+        recorder.record_applied("migrations", "7_auto")
+        loader.build_graph()
+        self.assertEqual(num_nodes(), 0)
+
+        recorder.flush()
diff --git a/tests/migrations/test_migrations_squashed_complex/1_auto.py b/tests/migrations/test_migrations_squashed_complex/1_auto.py
new file mode 100644
index 0000000000..25edcfa290
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/1_auto.py
@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/2_auto.py b/tests/migrations/test_migrations_squashed_complex/2_auto.py
new file mode 100644
index 0000000000..9107c35868
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/2_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "1_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/3_auto.py b/tests/migrations/test_migrations_squashed_complex/3_auto.py
new file mode 100644
index 0000000000..98e679fc12
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/3_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "2_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/3_squashed_5.py b/tests/migrations/test_migrations_squashed_complex/3_squashed_5.py
new file mode 100644
index 0000000000..ac1bcdee6d
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/3_squashed_5.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    replaces = [
+        ("migrations", "3_auto"),
+        ("migrations", "4_auto"),
+        ("migrations", "5_auto"),
+    ]
+
+    dependencies = [("migrations", "2_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/4_auto.py b/tests/migrations/test_migrations_squashed_complex/4_auto.py
new file mode 100644
index 0000000000..8fab746542
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/4_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "3_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/5_auto.py b/tests/migrations/test_migrations_squashed_complex/5_auto.py
new file mode 100644
index 0000000000..5dda63aae5
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/5_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "4_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/6_auto.py b/tests/migrations/test_migrations_squashed_complex/6_auto.py
new file mode 100644
index 0000000000..5ca558bc3b
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/6_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "5_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/7_auto.py b/tests/migrations/test_migrations_squashed_complex/7_auto.py
new file mode 100644
index 0000000000..e9f5533364
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/7_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "6_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_complex/__init__.py b/tests/migrations/test_migrations_squashed_complex/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_complex/__init__.py
diff --git a/tests/migrations/test_migrations_squashed_erroneous/1_auto.py b/tests/migrations/test_migrations_squashed_erroneous/1_auto.py
new file mode 100644
index 0000000000..25edcfa290
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_erroneous/1_auto.py
@@ -0,0 +1,11 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_erroneous/2_auto.py b/tests/migrations/test_migrations_squashed_erroneous/2_auto.py
new file mode 100644
index 0000000000..9107c35868
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_erroneous/2_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "1_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_erroneous/3_squashed_5.py b/tests/migrations/test_migrations_squashed_erroneous/3_squashed_5.py
new file mode 100644
index 0000000000..ac1bcdee6d
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_erroneous/3_squashed_5.py
@@ -0,0 +1,19 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    replaces = [
+        ("migrations", "3_auto"),
+        ("migrations", "4_auto"),
+        ("migrations", "5_auto"),
+    ]
+
+    dependencies = [("migrations", "2_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_erroneous/6_auto.py b/tests/migrations/test_migrations_squashed_erroneous/6_auto.py
new file mode 100644
index 0000000000..5ca558bc3b
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_erroneous/6_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "5_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_erroneous/7_auto.py b/tests/migrations/test_migrations_squashed_erroneous/7_auto.py
new file mode 100644
index 0000000000..e9f5533364
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_erroneous/7_auto.py
@@ -0,0 +1,13 @@
+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [("migrations", "6_auto")]
+
+    operations = [
+        migrations.RunPython(lambda apps, schema_editor: None)
+    ]
diff --git a/tests/migrations/test_migrations_squashed_erroneous/__init__.py b/tests/migrations/test_migrations_squashed_erroneous/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/migrations/test_migrations_squashed_erroneous/__init__.py