migration_status: Move get_migration_status to a new file.

This moves `get_migration_status` to its own file in
zerver/lib/migration_status.py. This is a prep work to refactor the
check migration function of import/export later on.

Some of the imports are moved into `get_migration_status` because we're
planning to share this file with `check-database-compatibility` which is
also called when one does `production-upgrade`, so we'd want to avoid
doing file-wide import on certain types of modules because it will fail
under that scenario.

In `test_fixtures.py`, `get_migration_status` is imported within
`Database.what_to_do_with_migrations` so that it is called after
`cov.start()` in `test-backend`. This is to avoid wierd interaction with
coverage, see more details in #33063.

Fixes #33063.

zerver/lib/migration_status.py

@@ -0,0 +1,41 @@
+import os
+import re
+from importlib import import_module
+from io import StringIO
+from typing import Any
+
+
+def get_migration_status(**options: Any) -> str:
+    from django.apps import apps
+    from django.core.management import call_command
+    from django.db import DEFAULT_DB_ALIAS, connections
+    from django.utils.module_loading import module_has_submodule
+
+    verbosity = options.get("verbosity", 1)
+
+    for app_config in apps.get_app_configs():
+        if module_has_submodule(app_config.module, "management"):
+            import_module(".management", app_config.name)
+
+    app_label = options["app_label"] if options.get("app_label") else None
+    db = options.get("database", DEFAULT_DB_ALIAS)
+    out = StringIO()
+    command_args = ["--list"]
+    if app_label:
+        command_args.append(app_label)
+
+    call_command(
+        "showmigrations",
+        *command_args,
+        database=db,
+        no_color=options.get("no_color", False),
+        settings=options.get("settings", os.environ["DJANGO_SETTINGS_MODULE"]),
+        stdout=out,
+        skip_checks=options.get("skip_checks", True),
+        traceback=options.get("traceback", True),
+        verbosity=verbosity,
+    )
+    connections.close_all()
+    out.seek(0)
+    output = out.read()
+    return re.sub(r"\x1b\[(1|0)m", "", output)

zerver/lib/test_fixtures.py

@@ -6,16 +6,10 @@ import shutil
 import subprocess
 import sys
 import time
-from importlib import import_module
-from io import StringIO
-from typing import Any
 
-from django.apps import apps
 from django.conf import settings
-from django.core.management import call_command
 from django.db import DEFAULT_DB_ALIAS, ProgrammingError, connection, connections
 from django.db.utils import OperationalError
-from django.utils.module_loading import module_has_submodule
 
 sys.path.append(os.path.dirname(os.path.dirname(os.path.dirname(__file__))))
 from scripts.lib.zulip_tools import (
@@ -117,6 +111,8 @@ class Database:
         )
 
     def what_to_do_with_migrations(self) -> str:
+        from zerver.lib.migration_status import get_migration_status
+
         status_fn = self.migration_status_path
         settings = self.settings
 
@@ -295,37 +291,6 @@ def update_test_databases_if_required(rebuild_test_database: bool = False) -> No
         run(["tools/setup/generate-fixtures"])
 
 
-def get_migration_status(**options: Any) -> str:
-    verbosity = options.get("verbosity", 1)
-
-    for app_config in apps.get_app_configs():
-        if module_has_submodule(app_config.module, "management"):
-            import_module(".management", app_config.name)
-
-    app_label = options["app_label"] if options.get("app_label") else None
-    db = options.get("database", DEFAULT_DB_ALIAS)
-    out = StringIO()
-    command_args = ["--list"]
-    if app_label:
-        command_args.append(app_label)
-
-    call_command(
-        "showmigrations",
-        *command_args,
-        database=db,
-        no_color=options.get("no_color", False),
-        settings=options.get("settings", os.environ["DJANGO_SETTINGS_MODULE"]),
-        stdout=out,
-        skip_checks=options.get("skip_checks", True),
-        traceback=options.get("traceback", True),
-        verbosity=verbosity,
-    )
-    connections.close_all()
-    out.seek(0)
-    output = out.read()
-    return re.sub(r"\x1b\[(1|0)m", "", output)
-
-
 def extract_migrations_as_list(migration_status: str) -> list[str]:
     MIGRATIONS_RE = re.compile(r"\[[X| ]\] (\d+_.+)\n")
     return MIGRATIONS_RE.findall(migration_status)

zerver/management/commands/get_migration_status.py

@@ -7,7 +7,7 @@ from typing_extensions import override
 
 from scripts.lib.zulip_tools import get_dev_uuid_var_path
 from zerver.lib.management import ZulipBaseCommand
-from zerver.lib.test_fixtures import get_migration_status
+from zerver.lib.migration_status import get_migration_status
 
 
 class Command(ZulipBaseCommand):