Chore: Add shared helpers for granting test permissions and use them (#14200)

src/paperless_testing/permissions.py

@@ -0,0 +1,43 @@
+"""Helpers that grant permissions to users and groups in tests.
+
+Two mechanisms, two names. A global permission is a Django model permission held
+by a user. An object permission is a guardian permission held on one object by a
+user or a group. They are not interchangeable.
+"""
+
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+
+from django.contrib.auth.models import Permission
+from guardian.shortcuts import assign_perm
+
+if TYPE_CHECKING:
+    from django.contrib.auth.models import Group
+    from django.contrib.auth.models import User
+    from django.db.models import Model
+
+
+def grant_global(user: User, *perms: str) -> None:
+    """Grant model-level permissions.
+
+    Each of perms is a codename or "app_label.codename". An unknown name raises
+    Permission.DoesNotExist.
+    """
+    for perm in perms:
+        app_label, _, codename = perm.rpartition(".")
+        lookup = {"codename": codename}
+        if app_label:
+            lookup["content_type__app_label"] = app_label
+        user.user_permissions.add(Permission.objects.get(**lookup))
+
+
+def grant_all_global(user: User) -> None:
+    """Grant every existing model-level permission without making a superuser."""
+    user.user_permissions.add(*Permission.objects.all())
+
+
+def grant_object(target: User | Group, obj: Model, *perms: str) -> None:
+    """Grant object-level permissions on obj to a user or a group."""
+    for perm in perms:
+        assign_perm(perm, target, obj)