test: test get_model_id

Author: kdmccormick

tests/openedx_django_lib/__init__.py

@@ -0,0 +1,35 @@
+"""
+Tests for our django typing utils
+"""
+from typing import assert_type
+
+from tests.test_django_app.models import MyTypedModel, RelatedTypedModel
+
+from openedx_django_lib.typing import get_model_id
+
+
+def test_get_model_id() -> None:
+    """
+    Test that get_model_id behaves as expected, both at runtime and during typechecking.
+    """
+    my_model = MyTypedModel()
+    related_model = RelatedTypedModel(my_model=my_model)
+
+    # Sanity checks
+    assert_type(my_model, MyTypedModel)
+    assert_type(my_model.id, MyTypedModel.ID)
+    assert_type(related_model.my_model, MyTypedModel)
+    assert_type(related_model.my_model.id, MyTypedModel.ID)
+    assert_type(related_model.my_model_id, MyTypedModel.ID)
+
+    # get_model_id on a model returns its id
+    assert get_model_id(my_model) == my_model.id
+    assert_type(get_model_id(my_model), MyTypedModel.ID)
+    assert get_model_id(related_model.my_model) == my_model.id
+    assert_type(get_model_id(related_model.my_model), MyTypedModel.ID)
+
+    # get_model_id on an id returns itself
+    assert get_model_id(my_model.id) == my_model.id
+    assert_type(get_model_id(my_model.id), MyTypedModel.ID)
+    assert get_model_id(related_model.my_model.id) == my_model.id
+    assert_type(get_model_id(related_model.my_model.id), MyTypedModel.ID)

tests/openedx_django_lib/test_typing.py

@@ -1,10 +1,8 @@
 """
 Models that are only for use in tests.
-
-These models are specifically for testing the `containers` API.
 """
 
-from typing import override
+from typing import override, NewType
 
 from django.core.exceptions import ValidationError
 from django.db import models
@@ -16,6 +14,34 @@
     PublishableEntityMixin,
     PublishableEntityVersionMixin,
 )
+from openedx_django_lib.fields import TypedBigAutoField
+
+
+class MyTypedModel(models.Model):
+    """
+    A model with nothing but a typed ID field.
+    """
+    MyTypedModelID = NewType("MyTypedModelID", int)
+    type ID = MyTypedModelID
+
+    class IDField(TypedBigAutoField[ID]):
+        pass
+
+    id = IDField(primary_key=True)
+
+
+class RelatedTypedModel(models.Model):
+    """
+    A model with nothing but a typed ID field and an FK to another typed model.
+    """
+    MyRelatedModelID = NewType("MyRelatedModelID", int)
+    type ID = MyRelatedModelID
+
+    class IDField(TypedBigAutoField[ID]):
+        pass
+
+    id = IDField(primary_key=True)
+    my_model = models.ForeignKey(MyTypedModel, on_delete=models.CASCADE)
 
 
 class TestEntity(PublishableEntityMixin):