Revert "Remove redundancy"

This reverts commit afecfcc.

Author: emyller

src/task_processor/routers.py

@@ -1,3 +1,4 @@
+from django.conf import settings
 from django.db.models import Model
 
 
@@ -8,10 +9,17 @@ class TaskProcessorRouter:
 
     route_app_labels = ["task_processor"]
 
+    @property
+    def is_enabled(self) -> bool:
+        return "task_processor" in settings.TASK_PROCESSOR_DATABASES
+
     def db_for_read(self, model: type[Model], **hints: None) -> str | None:
         """
         If enabled, route read operations to the task processor database
         """
+        if not self.is_enabled:
+            return None
+
         if model._meta.app_label in self.route_app_labels:
             return "task_processor"
 
@@ -21,6 +29,9 @@ def db_for_write(self, model: type[Model], **hints: None) -> str | None:
         """
         If enabled, route write operations to the task processor database
         """
+        if not self.is_enabled:
+            return None
+
         if model._meta.app_label in self.route_app_labels:
             return "task_processor"
 
@@ -30,6 +41,9 @@ def allow_relation(self, obj1: Model, obj2: Model, **hints: None) -> bool | None
         """
         If enabled, allow relations between task processor models
         """
+        if not self.is_enabled:
+            return None
+
         both_objects_from_task_processor = (
             obj1._meta.app_label in self.route_app_labels
             and obj2._meta.app_label in self.route_app_labels
@@ -58,6 +72,9 @@ def allow_migrate(
         - We want to make it easier to migrate to the new database, _or back_
           to a single database setup if needed. Running DDL consistently helps.
         """
+        if not self.is_enabled:
+            return None
+
         if app_label in self.route_app_labels:
             return db in ["default", "task_processor"]
 

tests/unit/task_processor/test_unit_task_processor_routers.py

@@ -4,27 +4,80 @@
 from django.apps import apps
 from django.conf import settings
 from django.db.models import Model
+from pytest_django.fixtures import SettingsWrapper
 from pytest_mock import MockerFixture
 
 from task_processor import routers
 
 
+@pytest.mark.parametrize(
+    "given_settings, expected",
+    [
+        ({"TASK_PROCESSOR_DATABASES": ["task_processor"]}, True),
+        ({"TASK_PROCESSOR_DATABASES": ["default", "task_processor"]}, True),
+        ({"TASK_PROCESSOR_DATABASES": ["default"]}, False),
+    ],
+)
+def test_TaskProcessorRouter__checks_whether_is_enabled(
+    settings: SettingsWrapper,
+    given_settings: dict[str, None | str],
+    expected: bool,
+) -> None:
+    # Given
+    for key, value in given_settings.items():
+        setattr(settings, key, value)
+
+    # When
+    router = routers.TaskProcessorRouter()
+
+    # Then
+    assert router.is_enabled is expected
+
+
 @pytest.mark.parametrize("model", apps.get_app_config("task_processor").get_models())
 def test_TaskProcessorRouter__enabled__routes_queries_to_task_processor_database(
     mocker: MockerFixture,
     model: type[Model],
 ) -> None:
     # Given
-    router = routers.TaskProcessorRouter()
+    mocker.patch.object(routers.TaskProcessorRouter, "is_enabled", new=True)
 
     # When
+    router = routers.TaskProcessorRouter()
     read_database = router.db_for_read(model)
     write_database = router.db_for_write(model)
 
     # Then
     assert read_database == write_database == "task_processor"
 
 
+@pytest.mark.parametrize("model", apps.get_app_config("task_processor").get_models())
+def test_TaskProcessorRouter__disabled__does_not_route_database_queries(
+    mocker: MockerFixture,
+    model: type[Model],
+) -> None:
+    # Given
+    mocker.patch.object(routers.TaskProcessorRouter, "is_enabled", new=False)
+
+    # When
+    router = routers.TaskProcessorRouter()
+    read_database = router.db_for_read(model)
+    write_database = router.db_for_write(model)
+    allows_relation = router.allow_relation(model(), model())
+    allows_migrate = {
+        router.allow_migrate("default", app_label="task_processor"),
+        router.allow_migrate("task_processor", app_label="task_processor"),
+        router.allow_migrate("other", app_label="task_processor"),
+        router.allow_migrate("task_processor", app_label="other"),
+    }
+
+    # Then
+    assert read_database is None
+    assert write_database is None
+    assert allows_relation is None
+    assert allows_migrate == {None}
+
+
 @pytest.mark.parametrize(
     "model1, model2, expected",
     [  # True if both models are from task_processor app
@@ -45,9 +98,10 @@ def test_TaskProcessorRouter__allow_relation__returns_according_to_given_models(
     expected: bool,
 ) -> None:
     # Given
-    router = routers.TaskProcessorRouter()
+    mocker.patch.object(routers.TaskProcessorRouter, "is_enabled", new=True)
 
     # When
+    router = routers.TaskProcessorRouter()
     allow_relation = router.allow_relation(model1(), model2())
 
     # Then
@@ -72,9 +126,10 @@ def test_TaskProcessorRouter__allow_migrate__applies_to_both_databases(
     mocker: MockerFixture,
 ) -> None:
     # Given
-    router = routers.TaskProcessorRouter()
+    mocker.patch.object(routers.TaskProcessorRouter, "is_enabled", new=True)
 
     # When
+    router = routers.TaskProcessorRouter()
     allow_migrate = router.allow_migrate(database, app_label)
 
     # Then