fix: model view set test case

.vscode/launch.json

@@ -0,0 +1,17 @@
+{
+  // Use IntelliSense to learn about possible attributes.
+  // Hover to view descriptions of existing attributes.
+  // For more information, visit: https://go.microsoft.com/fwlink/?linkid=830387
+  "version": "0.2.0",
+  "configurations": [
+    {
+      "name": "Pytest",
+      "type": "python",
+      "request": "test",
+      "justMyCode": false,
+      "presentation": {
+        "hidden": true
+      }
+    }
+  ]
+}

.vscode/settings.json

@@ -1,9 +1,39 @@
 {
+    "isort.path": [
+        ".venv/bin/python",
+        "-m",
+        "isort"
+    ],
+    "isort.args": [
+        "--settings-file=pyproject.toml"
+    ],
+    "black-formatter.path": [
+        ".venv/bin/python",
+        "-m",
+        "black"
+    ],
     "black-formatter.args": [
         "--config",
         "pyproject.toml"
     ],
+    "mypy-type-checker.path": [
+        ".venv/bin/python",
+        "-m",
+        "mypy"
+    ],
+    "mypy-type-checker.args": [
+        "--config-file=pyproject.toml"
+    ],
+    "pylint.path": [
+        ".venv/bin/python",
+        "-m",
+        "pylint"
+    ],
+    "pylint.args": [
+        "--rcfile=pyproject.toml"
+    ],
     "python.testing.pytestArgs": [
+        "-n=auto",
         "-c=pyproject.toml",
         "."
     ],

Pipfile

@@ -26,11 +26,18 @@ phonenumbers = "==8.12.12" # TODO: remove
 [dev-packages]
 black = "==23.1.0"
 pytest = "==7.2.1"
+pytest-env = "==0.8.1"
+pytest-xdist = {version = "==3.5.0", extras = ["psutil"]}
 pytest-django = "==4.5.2"
 django-extensions = "==3.2.1"
 pyparsing = "==3.0.9"
 pydot = "==1.4.2"
-pytest-env = "==0.8.1"
+pylint = "==3.0.2"
+pylint-django = "==2.5.5"
+isort = "==5.13.2"
+mypy = "==1.6.1"
+django-stubs = {version = "==4.2.6", extras = ["compatible-mypy"]}
+djangorestframework-stubs = {version = "==3.14.4", extras = ["compatible-mypy"]}
 
 [requires]
 python_version = "3.8"

codeforlife/models/__init__.py

@@ -1,21 +1,6 @@
-"""Helpers for module "django.db.models".
-https://docs.djangoproject.com/en/3.2/ref/models/
+"""
+© Ocado Group
+Created on 19/01/2024 at 15:20:45(+00:00).
 """
 
-import typing as t
-
-from django.db.models import Model as _Model
-
-
-class Model(_Model):
-    """A base class for all Django models.
-
-    Args:
-        _Model (django.db.models.Model): Django's model class.
-    """
-
-    id: int
-    pk: int
-
-
-AnyModel = t.TypeVar("AnyModel", bound=Model)
+from .base import *

codeforlife/models/base.py

@@ -0,0 +1,27 @@
+"""
+© Ocado Group
+Created on 19/01/2024 at 15:18:48(+00:00).
+
+Base model for all Django models.
+"""
+
+import typing as t
+
+from django.db.models import Model as _Model
+from django_stubs_ext.db.models import TypedModelMeta
+
+Id = t.TypeVar("Id")
+
+
+class Model(_Model, t.Generic[Id]):
+    """A base class for all Django models."""
+
+    id: Id
+    pk: Id
+
+    # pylint: disable-next=missing-class-docstring,too-few-public-methods
+    class Meta(TypedModelMeta):
+        abstract = True
+
+
+AnyModel = t.TypeVar("AnyModel", bound=Model)

codeforlife/models/signals/pre_save.py

@@ -4,9 +4,12 @@
 
 import typing as t
 
-from .. import AnyModel
+from django.db.models import Model
+
 from . import UpdateFields, _has_update_fields
 
+AnyModel = t.TypeVar("AnyModel", bound=Model)
+
 
 def was_created(instance: AnyModel):
     """Check if the instance was created.
@@ -37,30 +40,55 @@ def has_update_fields(actual: UpdateFields, expected: UpdateFields):
     return _has_update_fields(actual, expected)
 
 
-def has_previous_values(
+def check_previous_values(
     instance: AnyModel,
     predicates: t.Dict[str, t.Callable[[t.Any, t.Any], bool]],
 ):
-    """Check if the previous values are as expected.
+    """Check if the previous values are as expected. If the model has not been
+    created yet, the previous values are None.
 
     Args:
         instance: The current instance.
         predicates: A predicate for each field. It accepts the arguments
         (previous_value, value) and returns True if the values are as expected.
 
-    Raises:
-        ValueError: If arg 'instance' has not been created yet.
-
     Returns:
         If all the previous values are as expected.
     """
 
-    if not was_created(instance):
-        raise ValueError("Arg 'instance' has not been created yet.")
+    if was_created(instance):
+        previous_instance = instance.__class__.objects.get(pk=instance.pk)
+
+        def get_previous_value(field: str):
+            return getattr(previous_instance, field)
 
-    previous_instance = instance.__class__.objects.get(pk=instance.pk)
+    else:
+        # pylint: disable-next=unused-argument
+        def get_previous_value(field: str):
+            return None
 
     return all(
-        predicate(previous_instance[field], instance[field])
+        predicate(get_previous_value(field), getattr(instance, field))
         for field, predicate in predicates.items()
     )
+
+
+def previous_values_are_unequal(instance: AnyModel, fields: t.Set[str]):
+    """Check if all the previous values are not equal to the current values. If
+    the model has not been created yet, the previous values are None.
+
+    Args:
+        instance: The current instance.
+        fields: The fields that should not be equal.
+
+    Returns:
+        If all the previous values are not equal to the current values.
+    """
+
+    def predicate(v1, v2):
+        return v1 != v2
+
+    return check_previous_values(
+        instance,
+        {field: predicate for field in fields},
+    )

codeforlife/serializers/__init__.py

@@ -0,0 +1,6 @@
+"""
+© Ocado Group
+Created on 20/01/2024 at 11:19:12(+00:00).
+"""
+
+from .base import *

codeforlife/serializers/base.py

@@ -0,0 +1,21 @@
+"""
+© Ocado Group
+Created on 20/01/2024 at 11:19:24(+00:00).
+
+Base model serializers.
+"""
+
+import typing as t
+
+from django.db.models import Model
+from rest_framework.serializers import ModelSerializer as _ModelSerializer
+
+AnyModel = t.TypeVar("AnyModel", bound=Model)
+
+
+class ModelSerializer(_ModelSerializer[AnyModel], t.Generic[AnyModel]):
+    """Base model serializer for all model serializers."""
+
+    # pylint: disable-next=useless-parent-delegation
+    def update(self, instance, validated_data: t.Dict[str, t.Any]):
+        return super().update(instance, validated_data)

codeforlife/tests/__init__.py

@@ -1,2 +1,9 @@
-from .api import APITestCase, APIClient
-from .cron import CronTestCase, CronTestClient
+"""
+© Ocado Group
+Created on 19/01/2024 at 17:17:23(+00:00).
+
+Custom test cases.
+"""
+
+from .cron import CronTestCase
+from .model_view_set import ModelViewSetTestCase