From d082e9d3c2d2443afa348cb50f8d05762ad38ee2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=C3=89loi=20Rivard?= <eloi@yaal.coop>
Date: Mon, 2 Dec 2024 08:22:16 +0100
Subject: [PATCH] Revert "refactor: Resources must define a 'scim_schema'
 attribute"

This reverts commit 7514c8b318b35c0a0070d985dcdde851be8e7d08.

This was not compatible with Pydantic 2.10
---
 doc/changelog.rst                             | 22 -------------
 doc/tutorial.rst                              |  9 ++----
 scim2_models/base.py                          | 21 ++++++++----
 scim2_models/rfc7643/enterprise_user.py       |  5 +--
 scim2_models/rfc7643/group.py                 |  3 +-
 scim2_models/rfc7643/resource.py              | 29 ++++-------------
 scim2_models/rfc7643/resource_type.py         |  9 +++---
 scim2_models/rfc7643/schema.py                |  8 +++--
 .../rfc7643/service_provider_config.py        |  5 +--
 scim2_models/rfc7643/user.py                  |  3 +-
 scim2_models/rfc7644/bulk.py                  |  5 ++-
 scim2_models/rfc7644/error.py                 |  3 +-
 scim2_models/rfc7644/list_response.py         |  8 ++---
 scim2_models/rfc7644/message.py               | 12 -------
 scim2_models/rfc7644/patch_op.py              |  3 +-
 scim2_models/rfc7644/search_request.py        |  3 +-
 tests/test_dynamic_resources.py               | 32 +++++++++++--------
 tests/test_list_response.py                   |  3 +-
 tests/test_model_attributes.py                |  9 +++---
 tests/test_model_serialization.py             |  5 ++-
 tests/test_model_validation.py                |  7 ++--
 tests/test_models.py                          | 19 -----------
 tests/test_resource_extension.py              |  5 +--
 23 files changed, 75 insertions(+), 153 deletions(-)

diff --git a/doc/changelog.rst b/doc/changelog.rst
index 7d42c0d..0916964 100644
--- a/doc/changelog.rst
+++ b/doc/changelog.rst
@@ -1,28 +1,6 @@
 Changelog
 =========
 
-[0.3.0] - Unreleased
---------------------
-
-.. warning::
-
-   This version comes with breaking changes:
-
-   - :class:`~scim2_models.Resource`, :class:`~scim2_models.Extension` and :class:`~scim2_models.Message` must define a ``scim_schema`` attribute.
-
-     .. code-block:: python
-        :caption: Before
-
-        class MyResource(Resource):
-            schemas : list[str] = ["example:schema:MyResource"]
-
-     .. code-block:: python
-        :caption: After
-
-        class MyResource(Resource):
-            scim_schema: ClassVar[str] = "example:schema:MyResource"
-
-
 [0.2.7] - 2024-11-30
 --------------------
 
diff --git a/doc/tutorial.rst b/doc/tutorial.rst
index 76c4c06..8efcaa2 100644
--- a/doc/tutorial.rst
+++ b/doc/tutorial.rst
@@ -272,12 +272,11 @@ Custom models
 
 You can write your own model and use it the same way than the other scim2-models models.
 Just inherit from :class:`~scim2_models.Resource` for your main resource, or :class:`~scim2_models.Extension` for extensions.
-Then you need to define a ``scim_schema`` attribute, that is a class variable detailing the schema identifier of your model.
 Use :class:`~scim2_models.ComplexAttribute` as base class for complex attributes:
 
 .. code-block:: python
 
-    >>> from typing import Annotated, ClassVar, Optional, List
+    >>> from typing import Annotated, Optional, List
     >>> from scim2_models import Resource, Returned, Mutability, ComplexAttribute
     >>> from enum import Enum
 
@@ -289,7 +288,7 @@ Use :class:`~scim2_models.ComplexAttribute` as base class for complex attributes
     ...     """The pet color."""
 
     >>> class Pet(Resource):
-    ...     scim_schema : ClassVar[str] = "example:schemas:Pet"
+    ...     schemas: List[str] = ["example:schemas:Pet"]
     ...
     ...     name: Annotated[Optional[str], Mutability.immutable, Returned.always]
     ...     """The name of the pet."""
@@ -310,8 +309,6 @@ that can take type parameters to represent :rfc:`RFC7643 §7 'referenceTypes'<7
 
     >>> from typing import Literal
     >>> class PetOwner(Resource):
-    ...    scim_schema : ClassVar[str] = "examples:schema.PetOwner"
-    ...
     ...    pet: Reference[Literal["Pet"]]
 
 :class:`~scim2_models.Reference` has two special type parameters :data:`~scim2_models.ExternalReference` and :data:`~scim2_models.URIReference` that matches :rfc:`RFC7643 §7 <7643#section-7>` external and URI reference types.
@@ -328,7 +325,7 @@ This is useful for server implementations, so custom models or models provided b
     >>> class MyCustomResource(Resource):
     ...     """My awesome custom schema."""
     ...
-    ...     scim_schema: ClassVar[str] = "example:schemas:MyCustomResource"
+    ...     schemas: List[str] = ["example:schemas:MyCustomResource"]
     ...
     ...     foobar: Optional[str]
     ...
diff --git a/scim2_models/base.py b/scim2_models/base.py
index f33db4c..426484b 100644
--- a/scim2_models/base.py
+++ b/scim2_models/base.py
@@ -92,7 +92,11 @@ def validate_attribute_urn(
     if default_resource and default_resource not in resource_types:
         resource_types.append(default_resource)
 
-    default_schema = default_resource.scim_schema if default_resource else None
+    default_schema = (
+        default_resource.model_fields["schemas"].default[0]
+        if default_resource
+        else None
+    )
 
     schema: Optional[Any]
     schema, attribute_base = extract_schema_and_attribute_base(attribute_name)
@@ -609,7 +613,10 @@ def mark_with_schema(self):
             if not is_complex_attribute(attr_type):
                 continue
 
-            main_schema = getattr(self, "_scim_schema", None) or self.scim_schema
+            main_schema = (
+                getattr(self, "_schema", None)
+                or self.model_fields["schemas"].default[0]
+            )
 
             separator = ":" if isinstance(self, Resource) else "."
             schema = f"{main_schema}{separator}{field_name}"
@@ -617,9 +624,9 @@ def mark_with_schema(self):
             if attr_value := getattr(self, field_name):
                 if isinstance(attr_value, list):
                     for item in attr_value:
-                        item._scim_schema = schema
+                        item._schema = schema
                 else:
-                    attr_value._scim_schema = schema
+                    attr_value._schema = schema
 
     @field_serializer("*", mode="wrap")
     def scim_serializer(
@@ -786,7 +793,7 @@ def get_attribute_urn(self, field_name: str) -> str:
 
         See :rfc:`RFC7644 §3.10 <7644#section-3.10>`.
         """
-        main_schema = self.scim_schema
+        main_schema = self.model_fields["schemas"].default[0]
         alias = self.model_fields[field_name].serialization_alias or field_name
 
         # if alias contains a ':' this is an extension urn
@@ -797,7 +804,7 @@ def get_attribute_urn(self, field_name: str) -> str:
 class ComplexAttribute(BaseModel):
     """A complex attribute as defined in :rfc:`RFC7643 §2.3.8 <7643#section-2.3.8>`."""
 
-    _scim_schema: Optional[str] = None
+    _schema: Optional[str] = None
 
     def get_attribute_urn(self, field_name: str) -> str:
         """Build the full URN of the attribute.
@@ -805,7 +812,7 @@ def get_attribute_urn(self, field_name: str) -> str:
         See :rfc:`RFC7644 §3.10 <7644#section-3.10>`.
         """
         alias = self.model_fields[field_name].serialization_alias or field_name
-        return f"{self._scim_schema}.{alias}"
+        return f"{self._schema}.{alias}"
 
 
 class MultiValuedComplexAttribute(ComplexAttribute):
diff --git a/scim2_models/rfc7643/enterprise_user.py b/scim2_models/rfc7643/enterprise_user.py
index 4df9faa..9c9020d 100644
--- a/scim2_models/rfc7643/enterprise_user.py
+++ b/scim2_models/rfc7643/enterprise_user.py
@@ -1,5 +1,4 @@
 from typing import Annotated
-from typing import ClassVar
 from typing import Literal
 from typing import Optional
 
@@ -27,9 +26,7 @@ class Manager(ComplexAttribute):
 
 
 class EnterpriseUser(Extension):
-    scim_schema: ClassVar[str] = (
-        "urn:ietf:params:scim:schemas:extension:enterprise:2.0:User"
-    )
+    schemas: list[str] = ["urn:ietf:params:scim:schemas:extension:enterprise:2.0:User"]
 
     employee_number: Optional[str] = None
     """Numeric or alphanumeric identifier assigned to a person, typically based
diff --git a/scim2_models/rfc7643/group.py b/scim2_models/rfc7643/group.py
index 5083674..877b007 100644
--- a/scim2_models/rfc7643/group.py
+++ b/scim2_models/rfc7643/group.py
@@ -1,5 +1,4 @@
 from typing import Annotated
-from typing import ClassVar
 from typing import Literal
 from typing import Optional
 from typing import Union
@@ -32,7 +31,7 @@ class GroupMember(MultiValuedComplexAttribute):
 
 
 class Group(Resource):
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:schemas:core:2.0:Group"
+    schemas: list[str] = ["urn:ietf:params:scim:schemas:core:2.0:Group"]
 
     display_name: Optional[str] = None
     """A human-readable name for the Group."""
diff --git a/scim2_models/rfc7643/resource.py b/scim2_models/rfc7643/resource.py
index ece511d..69af464 100644
--- a/scim2_models/rfc7643/resource.py
+++ b/scim2_models/rfc7643/resource.py
@@ -78,13 +78,6 @@ class Meta(ComplexAttribute):
 
 
 class Extension(BaseModel):
-    def __init_subclass__(cls, **kwargs):
-        super().__init_subclass__(**kwargs)
-        if not hasattr(cls, "scim_schema"):
-            raise AttributeError(
-                f"{cls.__name__} did not define a scim_schema attribute"
-            )
-
     @classmethod
     def to_schema(cls):
         """Build a :class:`~scim2_models.Schema` from the current extension class."""
@@ -127,7 +120,7 @@ def __new__(cls, name, bases, attrs, **kwargs):
                 else [extensions]
             )
             for extension in extensions:
-                schema = extension.scim_schema
+                schema = extension.model_fields["schemas"].default[0]
                 attrs.setdefault("__annotations__", {})[extension.__name__] = Annotated[
                     Optional[extension],
                     WrapSerializer(extension_serializer),
@@ -143,18 +136,6 @@ def __new__(cls, name, bases, attrs, **kwargs):
 
 
 class Resource(BaseModel, Generic[AnyExtension], metaclass=ResourceMetaclass):
-    def __init_subclass__(cls, **kwargs):
-        super().__init_subclass__(**kwargs)
-        if not hasattr(cls, "scim_schema"):
-            raise AttributeError(
-                f"{cls.__name__} did not define a scim_schema attribute"
-            )
-
-        def init_schemas():
-            return [cls.scim_schema]
-
-        cls.model_fields["schemas"].default_factory = init_schemas
-
     schemas: list[str]
     """The "schemas" attribute is a REQUIRED attribute and is an array of
     Strings containing URIs that are used to indicate the namespaces of the
@@ -205,7 +186,9 @@ def get_extension_models(cls) -> dict[str, type]:
             else extension_models
         )
 
-        by_schema = {ext.scim_schema: ext for ext in extension_models}
+        by_schema = {
+            ext.model_fields["schemas"].default[0]: ext for ext in extension_models
+        }
         return by_schema
 
     @staticmethod
@@ -214,7 +197,7 @@ def get_by_schema(
     ) -> Optional[type]:
         """Given a resource type list and a schema, find the matching resource type."""
         by_schema = {
-            resource_type.scim_schema.lower(): resource_type
+            resource_type.model_fields["schemas"].default[0].lower(): resource_type
             for resource_type in (resource_types or [])
         }
         if with_extensions:
@@ -291,7 +274,7 @@ def compare_field_infos(fi1, fi2):
 def model_to_schema(model: type[BaseModel]):
     from scim2_models.rfc7643.schema import Schema
 
-    schema_urn = model.scim_schema
+    schema_urn = model.model_fields["schemas"].default[0]
     field_infos = dedicated_attributes(model)
     attributes = [
         model_attribute_to_attribute(model, attribute_name)
diff --git a/scim2_models/rfc7643/resource_type.py b/scim2_models/rfc7643/resource_type.py
index 612b462..84dfcf8 100644
--- a/scim2_models/rfc7643/resource_type.py
+++ b/scim2_models/rfc7643/resource_type.py
@@ -1,5 +1,4 @@
 from typing import Annotated
-from typing import ClassVar
 from typing import Optional
 
 from pydantic import Field
@@ -36,7 +35,7 @@ class SchemaExtension(ComplexAttribute):
 
 
 class ResourceType(Resource):
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:schemas:core:2.0:ResourceType"
+    schemas: list[str] = ["urn:ietf:params:scim:schemas:core:2.0:ResourceType"]
 
     name: Annotated[Optional[str], Mutability.read_only, Required.true] = None
     """The resource type name.
@@ -79,7 +78,7 @@ class ResourceType(Resource):
     @classmethod
     def from_resource(cls, resource_model: type[Resource]) -> Self:
         """Build a naive ResourceType from a resource model."""
-        schema = resource_model.scim_schema
+        schema = resource_model.model_fields["schemas"].default[0]
         name = schema.split(":")[-1]
         extensions = resource_model.__pydantic_generic_metadata__["args"]
         return ResourceType(
@@ -89,7 +88,9 @@ def from_resource(cls, resource_model: type[Resource]) -> Self:
             endpoint=f"/{name}s",
             schema_=schema,
             schema_extensions=[
-                SchemaExtension(schema_=extension.scim_schema, required=False)
+                SchemaExtension(
+                    schema_=extension.model_fields["schemas"].default[0], required=False
+                )
                 for extension in extensions
             ],
         )
diff --git a/scim2_models/rfc7643/schema.py b/scim2_models/rfc7643/schema.py
index 2c8c8e0..1a33463 100644
--- a/scim2_models/rfc7643/schema.py
+++ b/scim2_models/rfc7643/schema.py
@@ -3,7 +3,6 @@
 from enum import Enum
 from typing import Annotated
 from typing import Any
-from typing import ClassVar
 from typing import List  # noqa : UP005
 from typing import Literal
 from typing import Optional
@@ -65,7 +64,10 @@ def make_python_model(
             for attr in (obj.attributes or [])
             if attr.name
         }
-        pydantic_attributes["scim_schema"] = (ClassVar[str], obj.id)
+        pydantic_attributes["schemas"] = (
+            Optional[list[str]],
+            Field(default=[obj.id]),
+        )
 
     model_name = to_pascal(to_snake(obj.name))
     model = create_model(model_name, __base__=base, **pydantic_attributes)
@@ -238,7 +240,7 @@ def to_python(self) -> Optional[tuple[Any, Field]]:
 
 
 class Schema(Resource):
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:schemas:core:2.0:Schema"
+    schemas: list[str] = ["urn:ietf:params:scim:schemas:core:2.0:Schema"]
 
     id: Annotated[Optional[str], Mutability.read_only, Required.true] = None
     """The unique URI of the schema."""
diff --git a/scim2_models/rfc7643/service_provider_config.py b/scim2_models/rfc7643/service_provider_config.py
index 5f1cbba..784ffd8 100644
--- a/scim2_models/rfc7643/service_provider_config.py
+++ b/scim2_models/rfc7643/service_provider_config.py
@@ -1,6 +1,5 @@
 from enum import Enum
 from typing import Annotated
-from typing import ClassVar
 from typing import Optional
 
 from pydantic import Field
@@ -95,9 +94,7 @@ class Type(str, Enum):
 
 
 class ServiceProviderConfig(Resource):
-    scim_schema: ClassVar[str] = (
-        "urn:ietf:params:scim:schemas:core:2.0:ServiceProviderConfig"
-    )
+    schemas: list[str] = ["urn:ietf:params:scim:schemas:core:2.0:ServiceProviderConfig"]
 
     id: Annotated[
         Optional[str], Mutability.read_only, Returned.default, Uniqueness.global_
diff --git a/scim2_models/rfc7643/user.py b/scim2_models/rfc7643/user.py
index 034b330..44ea9ea 100644
--- a/scim2_models/rfc7643/user.py
+++ b/scim2_models/rfc7643/user.py
@@ -1,6 +1,5 @@
 from enum import Enum
 from typing import Annotated
-from typing import ClassVar
 from typing import Literal
 from typing import Optional
 from typing import Union
@@ -215,7 +214,7 @@ class X509Certificate(MultiValuedComplexAttribute):
 
 
 class User(Resource):
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:schemas:core:2.0:User"
+    schemas: list[str] = ["urn:ietf:params:scim:schemas:core:2.0:User"]
 
     user_name: Annotated[Optional[str], Uniqueness.server, Required.true] = None
     """Unique identifier for the User, typically used by the user to directly
diff --git a/scim2_models/rfc7644/bulk.py b/scim2_models/rfc7644/bulk.py
index 3585273..d2adc45 100644
--- a/scim2_models/rfc7644/bulk.py
+++ b/scim2_models/rfc7644/bulk.py
@@ -1,7 +1,6 @@
 from enum import Enum
 from typing import Annotated
 from typing import Any
-from typing import ClassVar
 from typing import Optional
 
 from pydantic import Field
@@ -54,7 +53,7 @@ class BulkRequest(Message):
         The models for Bulk operations are defined, but their behavior is not implemented nor tested yet.
     """
 
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:api:messages:2.0:BulkRequest"
+    schemas: list[str] = ["urn:ietf:params:scim:api:messages:2.0:BulkRequest"]
 
     fail_on_errors: Optional[int] = None
     """An integer specifying the number of errors that the service provider
@@ -75,7 +74,7 @@ class BulkResponse(Message):
         The models for Bulk operations are defined, but their behavior is not implemented nor tested yet.
     """
 
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:api:messages:2.0:BulkResponse"
+    schemas: list[str] = ["urn:ietf:params:scim:api:messages:2.0:BulkResponse"]
 
     operations: Optional[list[BulkOperation]] = Field(
         None, serialization_alias="Operations"
diff --git a/scim2_models/rfc7644/error.py b/scim2_models/rfc7644/error.py
index ebde80c..93ba783 100644
--- a/scim2_models/rfc7644/error.py
+++ b/scim2_models/rfc7644/error.py
@@ -1,5 +1,4 @@
 from typing import Annotated
-from typing import ClassVar
 from typing import Optional
 
 from pydantic import PlainSerializer
@@ -11,7 +10,7 @@
 class Error(Message):
     """Representation of SCIM API errors."""
 
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:api:messages:2.0:Error"
+    schemas: list[str] = ["urn:ietf:params:scim:api:messages:2.0:Error"]
 
     status: Annotated[Optional[int], PlainSerializer(int_to_str)] = None
     """The HTTP status code (see Section 6 of [RFC7231]) expressed as a JSON
diff --git a/scim2_models/rfc7644/list_response.py b/scim2_models/rfc7644/list_response.py
index b25f720..3241e9e 100644
--- a/scim2_models/rfc7644/list_response.py
+++ b/scim2_models/rfc7644/list_response.py
@@ -1,6 +1,5 @@
 from typing import Annotated
 from typing import Any
-from typing import ClassVar
 from typing import Generic
 from typing import Optional
 from typing import Union
@@ -45,7 +44,8 @@ def get_schema_from_payload(payload: Any) -> Optional[str]:
             )
 
             resource_types_schemas = [
-                resource_type.scim_schema for resource_type in resource_types
+                resource_type.model_fields["schemas"].default[0]
+                for resource_type in resource_types
             ]
             common_schemas = [
                 schema for schema in payload_schemas if schema in resource_types_schemas
@@ -55,7 +55,7 @@ def get_schema_from_payload(payload: Any) -> Optional[str]:
         discriminator = Discriminator(get_schema_from_payload)
 
         def get_tag(resource_type: type[BaseModel]) -> Tag:
-            return Tag(resource_type.scim_schema)
+            return Tag(resource_type.model_fields["schemas"].default[0])
 
         tagged_resources = [
             Annotated[resource_type, get_tag(resource_type)]
@@ -78,7 +78,7 @@ def __new__(cls, name, bases, attrs, **kwargs):
 
 
 class ListResponse(Message, Generic[AnyResource], metaclass=ListResponseMetaclass):
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:api:messages:2.0:ListResponse"
+    schemas: list[str] = ["urn:ietf:params:scim:api:messages:2.0:ListResponse"]
 
     total_results: Optional[int] = None
     """The total number of results returned by the list or query operation."""
diff --git a/scim2_models/rfc7644/message.py b/scim2_models/rfc7644/message.py
index ca4f8a1..8304f58 100644
--- a/scim2_models/rfc7644/message.py
+++ b/scim2_models/rfc7644/message.py
@@ -5,15 +5,3 @@ class Message(BaseModel):
     """SCIM protocol messages as defined by :rfc:`RFC7644 §3.1 <7644#section-3.1>`."""
 
     schemas: list[str]
-
-    def __init_subclass__(cls, **kwargs):
-        super().__init_subclass__(**kwargs)
-        if not hasattr(cls, "scim_schema"):
-            raise AttributeError(
-                f"{cls.__name__} did not define a scim_schema attribute"
-            )
-
-        def init_schemas():
-            return [cls.scim_schema]
-
-        cls.model_fields["schemas"].default_factory = init_schemas
diff --git a/scim2_models/rfc7644/patch_op.py b/scim2_models/rfc7644/patch_op.py
index c7fb0a2..6c83928 100644
--- a/scim2_models/rfc7644/patch_op.py
+++ b/scim2_models/rfc7644/patch_op.py
@@ -1,6 +1,5 @@
 from enum import Enum
 from typing import Any
-from typing import ClassVar
 from typing import Optional
 
 from pydantic import Field
@@ -58,7 +57,7 @@ class PatchOp(Message):
         The models for Patch operations are defined, but their behavior is not implemented nor tested yet.
     """
 
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:api:messages:2.0:PatchOp"
+    schemas: list[str] = ["urn:ietf:params:scim:api:messages:2.0:PatchOp"]
 
     operations: Optional[list[PatchOperation]] = Field(
         None, serialization_alias="Operations"
diff --git a/scim2_models/rfc7644/search_request.py b/scim2_models/rfc7644/search_request.py
index b4f3122..8f61b65 100644
--- a/scim2_models/rfc7644/search_request.py
+++ b/scim2_models/rfc7644/search_request.py
@@ -1,5 +1,4 @@
 from enum import Enum
-from typing import ClassVar
 from typing import Optional
 
 from pydantic import field_validator
@@ -14,7 +13,7 @@ class SearchRequest(Message):
     https://datatracker.ietf.org/doc/html/rfc7644#section-3.4.3
     """
 
-    scim_schema: ClassVar[str] = "urn:ietf:params:scim:api:messages:2.0:SearchRequest"
+    schemas: list[str] = ["urn:ietf:params:scim:api:messages:2.0:SearchRequest"]
 
     attributes: Optional[list[str]] = None
     """A multi-valued list of strings indicating the names of resource
diff --git a/tests/test_dynamic_resources.py b/tests/test_dynamic_resources.py
index 51890db..c817f06 100644
--- a/tests/test_dynamic_resources.py
+++ b/tests/test_dynamic_resources.py
@@ -25,7 +25,9 @@ def test_make_group_model_from_schema(load_sample):
     schema = Schema.model_validate(payload)
     Group = Resource.from_schema(schema)
 
-    assert Group.scim_schema == "urn:ietf:params:scim:schemas:core:2.0:Group"
+    assert Group.model_fields["schemas"].default == [
+        "urn:ietf:params:scim:schemas:core:2.0:Group"
+    ]
 
     # displayName
     assert Group.get_field_root_type("display_name") is str
@@ -151,7 +153,9 @@ def test_make_user_model_from_schema(load_sample):
     schema = Schema.model_validate(payload)
     User = Resource.from_schema(schema)
 
-    assert User.scim_schema == "urn:ietf:params:scim:schemas:core:2.0:User"
+    assert User.model_fields["schemas"].default == [
+        "urn:ietf:params:scim:schemas:core:2.0:User"
+    ]
 
     # user_name
     assert User.get_field_root_type("user_name") is str
@@ -1241,10 +1245,9 @@ def test_make_enterprise_user_model_from_schema(load_sample):
     schema = Schema.model_validate(payload)
     EnterpriseUser = Extension.from_schema(schema)
 
-    assert (
-        EnterpriseUser.scim_schema
-        == "urn:ietf:params:scim:schemas:extension:enterprise:2.0:User"
-    )
+    assert EnterpriseUser.model_fields["schemas"].default == [
+        "urn:ietf:params:scim:schemas:extension:enterprise:2.0:User"
+    ]
 
     # employee_number
     assert EnterpriseUser.get_field_root_type("employee_number") is str
@@ -1431,9 +1434,9 @@ def test_make_resource_type_model_from_schema(load_sample):
     schema = Schema.model_validate(payload)
     ResourceType = Resource.from_schema(schema)
 
-    assert (
-        ResourceType.scim_schema == "urn:ietf:params:scim:schemas:core:2.0:ResourceType"
-    )
+    assert ResourceType.model_fields["schemas"].default == [
+        "urn:ietf:params:scim:schemas:core:2.0:ResourceType"
+    ]
 
     # id
     assert ResourceType.get_field_root_type("id") is str
@@ -1624,10 +1627,9 @@ def test_make_service_provider_config_model_from_schema(load_sample):
     schema = Schema.model_validate(payload)
     ServiceProviderConfig = Resource.from_schema(schema)
 
-    assert (
-        ServiceProviderConfig.scim_schema
-        == "urn:ietf:params:scim:schemas:core:2.0:ServiceProviderConfig"
-    )
+    assert ServiceProviderConfig.model_fields["schemas"].default == [
+        "urn:ietf:params:scim:schemas:core:2.0:ServiceProviderConfig"
+    ]
 
     # documentation_uri
     assert (
@@ -2161,7 +2163,9 @@ def test_make_schema_model_from_schema(load_sample):
     schema = Schema.model_validate(payload)
     Schema_ = Resource.from_schema(schema)
 
-    assert Schema_.scim_schema == "urn:ietf:params:scim:schemas:core:2.0:Schema"
+    assert Schema_.model_fields["schemas"].default == [
+        "urn:ietf:params:scim:schemas:core:2.0:Schema"
+    ]
 
     # id
     assert Schema_.get_field_root_type("id") is str
diff --git a/tests/test_list_response.py b/tests/test_list_response.py
index 938566a..9c410e5 100644
--- a/tests/test_list_response.py
+++ b/tests/test_list_response.py
@@ -1,4 +1,3 @@
-from typing import ClassVar
 from typing import Union
 
 import pytest
@@ -108,7 +107,7 @@ def test_mixed_types(load_sample):
 
 
 class Foobar(Resource):
-    scim_schema: ClassVar[str] = "foobarschema"
+    schemas: list[str] = ["foobarschema"]
 
 
 def test_mixed_types_type_missing(load_sample):
diff --git a/tests/test_model_attributes.py b/tests/test_model_attributes.py
index 8bef1df..087d0e7 100644
--- a/tests/test_model_attributes.py
+++ b/tests/test_model_attributes.py
@@ -1,6 +1,5 @@
 import uuid
 from typing import Annotated
-from typing import ClassVar
 from typing import Optional
 
 import pytest
@@ -21,7 +20,7 @@ class Sub(ComplexAttribute):
 
 
 class Sup(Resource):
-    scim_schema: ClassVar[str] = "urn:example:2.0:Sup"
+    schemas: list[str] = ["urn:example:2.0:Sup"]
     dummy: str
     sub: Sub
     subs: list[Sub]
@@ -45,7 +44,7 @@ class Baz(ComplexAttribute):
 
 
 class Foo(Resource):
-    scim_schema: ClassVar[str] = "urn:example:2.0:Foo"
+    schemas: list[str] = ["urn:example:2.0:Foo"]
     sub: Annotated[ReturnedModel, Returned.default]
     bar: str
     snake_case: str
@@ -53,7 +52,7 @@ class Foo(Resource):
 
 
 class Bar(Resource):
-    scim_schema: ClassVar[str] = "urn:example:2.0:Bar"
+    schemas: list[str] = ["urn:example:2.0:Bar"]
     sub: Annotated[ReturnedModel, Returned.default]
     bar: str
     snake_case: str
@@ -61,7 +60,7 @@ class Bar(Resource):
 
 
 class Extension(Resource):
-    scim_schema: ClassVar[str] = "urn:example:2.0:Extension"
+    schemas: list[str] = ["urn:example:2.0:Extension"]
     baz: str
 
 
diff --git a/tests/test_model_serialization.py b/tests/test_model_serialization.py
index e0cc596..b8e644d 100644
--- a/tests/test_model_serialization.py
+++ b/tests/test_model_serialization.py
@@ -1,5 +1,4 @@
 from typing import Annotated
-from typing import ClassVar
 from typing import Optional
 
 import pytest
@@ -19,7 +18,7 @@ class SubRetModel(ComplexAttribute):
 
 
 class SupRetResource(Resource):
-    scim_schema: ClassVar[str] = "org:example:SupRetResource"
+    schemas: list[str] = ["org:example:SupRetResource"]
 
     always_returned: Annotated[Optional[str], Returned.always] = None
     never_returned: Annotated[Optional[str], Returned.never] = None
@@ -30,7 +29,7 @@ class SupRetResource(Resource):
 
 
 class MutResource(Resource):
-    scim_schema: ClassVar[str] = "org:example:MutResource"
+    schemas: list[str] = ["org:example:MutResource"]
 
     read_only: Annotated[Optional[str], Mutability.read_only] = None
     read_write: Annotated[Optional[str], Mutability.read_write] = None
diff --git a/tests/test_model_validation.py b/tests/test_model_validation.py
index 5161819..35e4282 100644
--- a/tests/test_model_validation.py
+++ b/tests/test_model_validation.py
@@ -1,5 +1,4 @@
 from typing import Annotated
-from typing import ClassVar
 from typing import Optional
 
 import pytest
@@ -13,7 +12,7 @@
 
 
 class RetResource(Resource):
-    scim_schema: ClassVar[str] = "org:example:RetResource"
+    schemas: list[str] = ["org:example:RetResource"]
 
     always_returned: Annotated[Optional[str], Returned.always] = None
     never_returned: Annotated[Optional[str], Returned.never] = None
@@ -22,7 +21,7 @@ class RetResource(Resource):
 
 
 class MutResource(Resource):
-    scim_schema: ClassVar[str] = "org:example:MutResource"
+    schemas: list[str] = ["org:example:MutResource"]
 
     read_only: Annotated[Optional[str], Mutability.read_only] = None
     read_write: Annotated[Optional[str], Mutability.read_write] = None
@@ -31,7 +30,7 @@ class MutResource(Resource):
 
 
 class ReqResource(Resource):
-    scim_schema: ClassVar[str] = "org:example:ReqResource"
+    schemas: list[str] = ["org:example:ReqResource"]
 
     required: Annotated[Optional[str], Required.true] = None
     optional: Annotated[Optional[str], Required.false] = None
diff --git a/tests/test_models.py b/tests/test_models.py
index f853b49..88d2b11 100644
--- a/tests/test_models.py
+++ b/tests/test_models.py
@@ -1,16 +1,12 @@
 import os
 from typing import Union
 
-import pytest
-
 from scim2_models import BulkRequest
 from scim2_models import BulkResponse
 from scim2_models import EnterpriseUser
 from scim2_models import Error
-from scim2_models import Extension
 from scim2_models import Group
 from scim2_models import ListResponse
-from scim2_models import Message
 from scim2_models import PatchOp
 from scim2_models import Resource
 from scim2_models import ResourceType
@@ -161,18 +157,3 @@ def test_everything_is_optional():
     ]
     for model in models:
         model()
-
-
-def test_scim_schema_is_mandatory():
-    """Check that the scim_schema attribute is needed to define new resources."""
-    with pytest.raises(AttributeError):
-
-        class InvalidResource(Resource): ...
-
-    with pytest.raises(AttributeError):
-
-        class InvalidExtension(Extension): ...
-
-    with pytest.raises(AttributeError):
-
-        class InvalidMessage(Message): ...
diff --git a/tests/test_resource_extension.py b/tests/test_resource_extension.py
index 70a5a7e..950a9f0 100644
--- a/tests/test_resource_extension.py
+++ b/tests/test_resource_extension.py
@@ -1,5 +1,4 @@
 import datetime
-from typing import ClassVar
 from typing import Optional
 from typing import Union
 
@@ -202,9 +201,7 @@ def test_invalid_setitem():
 
 
 class SuperHero(Extension):
-    scim_schema: ClassVar[str] = (
-        "urn:ietf:params:scim:schemas:extension:enterprise:2.0:User"
-    )
+    schemas: list[str] = ["urn:ietf:params:scim:schemas:extension:enterprise:2.0:User"]
 
     superpower: Optional[str] = None
     """The superhero superpower."""