@@ -16,7 +16,7 @@ The current version 3.0.0a2 of GraphQL-core is up-to-date
 with GraphQL.js version 14.4.2.
 
 All parts of the API are covered by an extensive test suite
-of currently 1933 unit tests.
+of currently 1965 unit tests.
 
 
 ## Documentation

@@ -183,13 +183,15 @@ class GraphQLNamedType(GraphQLType):
 
 name: str
 description: Optional[str]
+extensions: Optional[Dict[str, Any]]
 ast_node: Optional[TypeDefinitionNode]
 extension_ast_nodes: Optional[FrozenList[TypeExtensionNode]]
 
 def __init__(
 self,
 name: str,
 description: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: TypeDefinitionNode = None,
 extension_ast_nodes: Sequence[TypeExtensionNode] = None,
 ) -> None:
@@ -199,6 +201,11 @@ def __init__(
 raise TypeError("The name must be a string.")
 if description is not None and not isinstance(description, str):
 raise TypeError("The description must be a string.")
+if extensions is not None and (
+not isinstance(extensions, dict)
+or not all(isinstance(key, str) for key in extensions)
+):
+raise TypeError(f"{name} extensions must be a dictionary with string keys.")
 if ast_node and not isinstance(ast_node, TypeDefinitionNode):
 raise TypeError(f"{name} AST node must be a TypeDefinitionNode.")
 if extension_ast_nodes:
@@ -215,6 +222,7 @@ def __init__(
 extension_ast_nodes = None
 self.name = name
 self.description = description
+self.extensions = extensions
 self.ast_node = ast_node
 self.extension_ast_nodes = extension_ast_nodes
 
@@ -228,6 +236,7 @@ def to_kwargs(self) -> Dict[str, Any]:
 return dict(
 name=self.name,
 description=self.description,
+extensions=self.extensions,
 ast_node=self.ast_node,
 extension_ast_nodes=self.extension_ast_nodes or FrozenList(),
 )
@@ -306,15 +315,17 @@ def __init__(
 self,
 name: str,
 serialize: GraphQLScalarSerializer = None,
-description: str = None,
 parse_value: GraphQLScalarValueParser = None,
 parse_literal: GraphQLScalarLiteralParser = None,
+description: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: ScalarTypeDefinitionNode = None,
 extension_ast_nodes: Sequence[ScalarTypeExtensionNode] = None,
 ) -> None:
 super().__init__(
 name=name,
 description=description,
+extensions=extensions,
 ast_node=ast_node,
 extension_ast_nodes=extension_ast_nodes,
 )
@@ -415,12 +426,13 @@ def assert_scalar_type(type_: Any) -> GraphQLScalarType:
 class GraphQLField:
 """Definition of a GraphQL field"""
 
-description: Optional[str]
 type: "GraphQLOutputType"
 args: GraphQLArgumentMap
 resolve: Optional["GraphQLFieldResolver"]
 subscribe: Optional["GraphQLFieldResolver"]
+description: Optional[str]
 deprecation_reason: Optional[str]
+extensions: Optional[Dict[str, Any]]
 ast_node: Optional[FieldDefinitionNode]
 
 def __init__(
@@ -431,6 +443,7 @@ def __init__(
 subscribe: "GraphQLFieldResolver" = None,
 description: str = None,
 deprecation_reason: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: FieldDefinitionNode = None,
 ) -> None:
 if not is_output_type(type_):
@@ -462,14 +475,20 @@ def __init__(
 raise TypeError("The description must be a string.")
 if deprecation_reason is not None and not isinstance(deprecation_reason, str):
 raise TypeError("The deprecation reason must be a string.")
+if extensions is not None and (
+not isinstance(extensions, dict)
+or not all(isinstance(key, str) for key in extensions)
+):
+raise TypeError("Field extensions must be a dictionary with string keys.")
 if ast_node and not isinstance(ast_node, FieldDefinitionNode):
 raise TypeError("Field AST node must be a FieldDefinitionNode.")
 self.type = type_
 self.args = args or {}
 self.resolve = resolve
 self.subscribe = subscribe
-self.deprecation_reason = deprecation_reason
 self.description = description
+self.deprecation_reason = deprecation_reason
+self.extensions = extensions
 self.ast_node = ast_node
 
 def __repr__(self):
@@ -486,16 +505,18 @@ def __eq__(self, other):
 and self.resolve == other.resolve
 and self.description == other.description
 and self.deprecation_reason == other.deprecation_reason
+and self.extensions == other.extensions
 )
 
 def to_kwargs(self) -> Dict[str, Any]:
 return dict(
-description=self.description,
 type_=self.type,
 args=self.args.copy() if self.args else None,
 resolve=self.resolve,
 subscribe=self.subscribe,
 deprecation_reason=self.deprecation_reason,
+description=self.description,
+extensions=self.extensions,
 ast_node=self.ast_node,
 )
 
@@ -550,10 +571,11 @@ class GraphQLResolveInfo(NamedTuple):
 class GraphQLArgument:
 """Definition of a GraphQL argument"""
 
-description: Optional[str]
 type: "GraphQLInputType"
 default_value: Any
+description: Optional[str]
 out_name: Optional[str] # for transforming names (extension of GraphQL.js)
+extensions: Optional[Dict[str, Any]]
 ast_node: Optional[InputValueDefinitionNode]
 
 def __init__(
@@ -562,6 +584,7 @@ def __init__(
 default_value: Any = INVALID,
 description: str = None,
 out_name: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: InputValueDefinitionNode = None,
 ) -> None:
 if not is_input_type(type_):
@@ -570,12 +593,20 @@ def __init__(
 raise TypeError("Argument description must be a string.")
 if out_name is not None and not isinstance(out_name, str):
 raise TypeError("Argument out name must be a string.")
+if extensions is not None and (
+not isinstance(extensions, dict)
+or not all(isinstance(key, str) for key in extensions)
+):
+raise TypeError(
+"Argument extensions must be a dictionary with string keys."
+)
 if ast_node and not isinstance(ast_node, InputValueDefinitionNode):
 raise TypeError("Argument AST node must be an InputValueDefinitionNode.")
 self.type = type_
 self.default_value = default_value
 self.description = description
 self.out_name = out_name
+self.extensions = extensions
 self.ast_node = ast_node
 
 def __eq__(self, other):
@@ -585,14 +616,16 @@ def __eq__(self, other):
 and self.default_value == other.default_value
 and self.description == other.description
 and self.out_name == other.out_name
+and self.extensions == other.extensions
 )
 
 def to_kwargs(self) -> Dict[str, Any]:
 return dict(
-description=self.description,
 type_=self.type,
 default_value=self.default_value,
+description=self.description,
 out_name=self.out_name,
+extensions=self.extensions,
 ast_node=self.ast_node,
 )
 
@@ -645,13 +678,15 @@ def __init__(
 fields: Thunk[GraphQLFieldMap],
 interfaces: Thunk[Sequence["GraphQLInterfaceType"]] = None,
 is_type_of: GraphQLIsTypeOfFn = None,
+extensions: Dict[str, Any] = None,
 description: str = None,
 ast_node: ObjectTypeDefinitionNode = None,
 extension_ast_nodes: Sequence[ObjectTypeExtensionNode] = None,
 ) -> None:
 super().__init__(
 name=name,
 description=description,
+extensions=extensions,
 ast_node=ast_node,
 extension_ast_nodes=extension_ast_nodes,
 )
@@ -763,12 +798,14 @@ def __init__(
 fields: Thunk[GraphQLFieldMap] = None,
 resolve_type: GraphQLTypeResolver = None,
 description: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: InterfaceTypeDefinitionNode = None,
 extension_ast_nodes: Sequence[InterfaceTypeExtensionNode] = None,
 ) -> None:
 super().__init__(
 name=name,
 description=description,
+extensions=extensions,
 ast_node=ast_node,
 extension_ast_nodes=extension_ast_nodes,
 )
@@ -788,7 +825,6 @@ def __init__(
 )
 self._fields = fields
 self.resolve_type = resolve_type
-self.description = description
 
 def to_kwargs(self) -> Dict[str, Any]:
 return dict(
@@ -864,12 +900,14 @@ def __init__(
 types: Thunk[Sequence[GraphQLObjectType]],
 resolve_type: GraphQLTypeResolver = None,
 description: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: UnionTypeDefinitionNode = None,
 extension_ast_nodes: Sequence[UnionTypeExtensionNode] = None,
 ) -> None:
 super().__init__(
 name=name,
 description=description,
+extensions=extensions,
 ast_node=ast_node,
 extension_ast_nodes=extension_ast_nodes,
 )
@@ -967,12 +1005,14 @@ def __init__(
 name: str,
 values: Union[GraphQLEnumValueMap, Dict[str, Any], Type[Enum]],
 description: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: EnumTypeDefinitionNode = None,
 extension_ast_nodes: Sequence[EnumTypeExtensionNode] = None,
 ) -> None:
 super().__init__(
 name=name,
 description=description,
+extensions=extensions,
 ast_node=ast_node,
 extension_ast_nodes=extension_ast_nodes,
 )
@@ -1080,13 +1120,15 @@ class GraphQLEnumValue:
 value: Any
 description: Optional[str]
 deprecation_reason: Optional[str]
+extensions: Optional[Dict[str, Any]]
 ast_node: Optional[EnumValueDefinitionNode]
 
 def __init__(
 self,
 value: Any = None,
 description: str = None,
 deprecation_reason: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: EnumValueDefinitionNode = None,
 ) -> None:
 if description is not None and not isinstance(description, str):
@@ -1095,11 +1137,19 @@ def __init__(
 raise TypeError(
 "The deprecation reason for the enum value must be a string."
 )
+if extensions is not None and (
+not isinstance(extensions, dict)
+or not all(isinstance(key, str) for key in extensions)
+):
+raise TypeError(
+"Enum value extensions must be a dictionary with string keys."
+)
 if ast_node and not isinstance(ast_node, EnumValueDefinitionNode):
 raise TypeError("AST node must be an EnumValueDefinitionNode.")
 self.value = value
 self.description = description
 self.deprecation_reason = deprecation_reason
+self.extensions = extensions
 self.ast_node = ast_node
 
 def __eq__(self, other):
@@ -1108,13 +1158,15 @@ def __eq__(self, other):
 and self.value == other.value
 and self.description == other.description
 and self.deprecation_reason == other.deprecation_reason
+and self.extensions == other.extensions
 )
 
 def to_kwargs(self) -> Dict[str, Any]:
 return dict(
 value=self.value,
 description=self.description,
 deprecation_reason=self.deprecation_reason,
+extensions=self.extensions,
 ast_node=self.ast_node,
 )
 
@@ -1161,12 +1213,14 @@ def __init__(
 fields: Thunk[GraphQLInputFieldMap],
 description: str = None,
 out_type: GraphQLInputFieldOutType = None,
+extensions: Dict[str, Any] = None,
 ast_node: InputObjectTypeDefinitionNode = None,
 extension_ast_nodes: Sequence[InputObjectTypeExtensionNode] = None,
 ) -> None:
 super().__init__(
 name=name,
 description=description,
+extensions=extensions,
 ast_node=ast_node,
 extension_ast_nodes=extension_ast_nodes,
 )
@@ -1252,6 +1306,7 @@ class GraphQLInputField:
 default_value: Any
 description: Optional[str]
 out_name: Optional[str] # for transforming names (extension of GraphQL.js)
+extensions: Optional[Dict[str, Any]]
 ast_node: Optional[InputValueDefinitionNode]
 
 def __init__(
@@ -1260,6 +1315,7 @@ def __init__(
 default_value: Any = INVALID,
 description: str = None,
 out_name: str = None,
+extensions: Dict[str, Any] = None,
 ast_node: InputValueDefinitionNode = None,
 ) -> None:
 if not is_input_type(type_):
@@ -1268,12 +1324,20 @@ def __init__(
 raise TypeError("Input field description must be a string.")
 if out_name is not None and not isinstance(out_name, str):
 raise TypeError("Input field out name must be a string.")
+if extensions is not None and (
+not isinstance(extensions, dict)
+or not all(isinstance(key, str) for key in extensions)
+):
+raise TypeError(
+"Input field extensions must be a dictionary with string keys."
+)
 if ast_node and not isinstance(ast_node, InputValueDefinitionNode):
 raise TypeError("Input field AST node must be an InputValueDefinitionNode.")
 self.type = type_
 self.default_value = default_value
 self.description = description
 self.out_name = out_name
+self.extensions = extensions
 self.ast_node = ast_node
 
 def __eq__(self, other):
@@ -1282,15 +1346,17 @@ def __eq__(self, other):
 and self.type == other.type
 and self.default_value == other.default_value
 and self.description == other.description
+and self.extensions == other.extensions
 and self.out_name == other.out_name
 )
 
 def to_kwargs(self) -> Dict[str, Any]:
 return dict(
 type_=self.type,
-description=self.description,
 default_value=self.default_value,
+description=self.description,
 out_name=self.out_name,
+extensions=self.extensions,
 ast_node=self.ast_node,
 )