Fixed #23406 -- Allowed migrations to be loaded from .pyc files.

3 files changed, 34 insertions, 0 deletions

diff --git a/tests/migrations/test_loader.py b/tests/migrations/test_loader.py
index e0e7e3d258..eade230640 100644
--- a/tests/migrations/test_loader.py
+++ b/tests/migrations/test_loader.py
@@ -1,3 +1,6 @@
+import compileall
+import os
+
 from django.db import connection, connections
 from django.db.migrations.exceptions import (
     AmbiguityError, InconsistentMigrationHistory, NodeNotFoundError,
@@ -6,6 +9,8 @@ from django.db.migrations.loader import MigrationLoader
 from django.db.migrations.recorder import MigrationRecorder
 from django.test import TestCase, modify_settings, override_settings
 
+from .test_base import MigrationTestBase
+
 
 class RecorderTests(TestCase):
     """
@@ -494,3 +499,32 @@ class LoaderTests(TestCase):
             ('app1', '4_auto'),
         }
         self.assertEqual(plan, expected_plan)
+
+
+class PycLoaderTests(MigrationTestBase):
+
+    def test_valid(self):
+        """
+        To support frozen environments, MigrationLoader loads .pyc migrations.
+        """
+        with self.temporary_migration_module(module='migrations.test_migrations') as migration_dir:
+            # Compile .py files to .pyc files and delete .py files.
+            compileall.compile_dir(migration_dir, force=True, quiet=1, legacy=True)
+            for name in os.listdir(migration_dir):
+                if name.endswith('.py'):
+                    os.remove(os.path.join(migration_dir, name))
+            loader = MigrationLoader(connection)
+            self.assertIn(('migrations', '0001_initial'), loader.disk_migrations)
+
+    def test_invalid(self):
+        """
+        MigrationLoader reraises ImportErrors caused by "bad magic number" pyc
+        files with a more helpful message.
+        """
+        with self.temporary_migration_module(module='migrations.test_migrations_bad_pyc'):
+            msg = (
+                "Couldn't import '\w+.migrations.0001_initial' as it appears "
+                "to be a stale .pyc file."
+            )
+            with self.assertRaisesRegex(ImportError, msg):
+                MigrationLoader(connection)
diff --git a/tests/migrations/test_migrations_bad_pyc/0001_initial.pyc b/tests/migrations/test_migrations_bad_pyc/0001_initial.pyc
new file mode 100644
index 0000000000..07854f4aeb
--- /dev/null
+++ b/tests/migrations/test_migrations_bad_pyc/0001_initial.pyc
diff --git a/tests/migrations/test_migrations_bad_pyc/__init__.py b/tests/migrations/test_migrations_bad_pyc/__init__.py
new file mode 100644
index 0000000000..e69de29bb2
--- /dev/null
+++ b/tests/migrations/test_migrations_bad_pyc/__init__.py