Use explicit optional type on arguments

mypy.ini

@@ -1,7 +1,7 @@
 [mypy]
 python_version = 3.8
 check_untyped_defs = True
-no_implicit_optional = False
+no_implicit_optional = True
 strict_optional = True
 warn_redundant_casts = True
 warn_unused_ignores = True

src/graphql/error/graphql_error.py

@@ -85,12 +85,12 @@ class GraphQLError(Exception):
     def __init__(
         self,
         message: str,
-        nodes: Union[Collection["Node"], "Node"] = None,
-        source: "Source" = None,
-        positions: Collection[int] = None,
-        path: Collection[Union[str, int]] = None,
-        original_error: Exception = None,
-        extensions: Dict[str, Any] = None,
+        nodes: Union[Collection["Node"], "Node", None] = None,
+        source: Optional["Source"] = None,
+        positions: Optional[Collection[int]] = None,
+        path: Optional[Collection[Union[str, int]]] = None,
+        original_error: Optional[Exception] = None,
+        extensions: Optional[Dict[str, Any]] = None,
     ) -> None:
         super().__init__(message)
         self.message = message

src/graphql/execution/execute.py

@@ -117,12 +117,12 @@ def execute(
     document: DocumentNode,
     root_value: Any = None,
     context_value: Any = None,
-    variable_values: Dict[str, Any] = None,
-    operation_name: str = None,
-    field_resolver: GraphQLFieldResolver = None,
-    type_resolver: GraphQLTypeResolver = None,
-    middleware: Middleware = None,
-    execution_context_class: Type["ExecutionContext"] = None,
+    variable_values: Optional[Dict[str, Any]] = None,
+    operation_name: Optional[str] = None,
+    field_resolver: Optional[GraphQLFieldResolver] = None,
+    type_resolver: Optional[GraphQLTypeResolver] = None,
+    middleware: Optional[Middleware] = None,
+    execution_context_class: Optional[Type["ExecutionContext"]] = None,
 ) -> AwaitableOrValue[ExecutionResult]:
     """Execute a GraphQL operation.
 
@@ -222,11 +222,11 @@ def build(
         document: DocumentNode,
         root_value: Any = None,
         context_value: Any = None,
-        raw_variable_values: Dict[str, Any] = None,
-        operation_name: str = None,
-        field_resolver: GraphQLFieldResolver = None,
-        type_resolver: GraphQLTypeResolver = None,
-        middleware: Middleware = None,
+        raw_variable_values: Optional[Dict[str, Any]] = None,
+        operation_name: Optional[str] = None,
+        field_resolver: Optional[GraphQLFieldResolver] = None,
+        type_resolver: Optional[GraphQLTypeResolver] = None,
+        middleware: Optional[Middleware] = None,
     ) -> Union[List[GraphQLError], "ExecutionContext"]:
         """Build an execution context
 
@@ -1030,7 +1030,7 @@ def collect_subfields(
 def assert_valid_execution_arguments(
     schema: GraphQLSchema,
     document: DocumentNode,
-    raw_variable_values: Dict[str, Any] = None,
+    raw_variable_values: Optional[Dict[str, Any]] = None,
 ) -> None:
     """Check that the arguments are acceptable.
 

src/graphql/execution/values.py

@@ -37,7 +37,7 @@ def get_variable_values(
     schema: GraphQLSchema,
     var_def_nodes: FrozenList[VariableDefinitionNode],
     inputs: Dict[str, Any],
-    max_errors: int = None,
+    max_errors: Optional[int] = None,
 ) -> CoercedVariableValues:
     """Get coerced variable values based on provided definitions.
 
@@ -144,7 +144,7 @@ def on_input_value_error(
 def get_argument_values(
     type_def: Union[GraphQLField, GraphQLDirective],
     node: Union[FieldNode, DirectiveNode],
-    variable_values: Dict[str, Any] = None,
+    variable_values: Optional[Dict[str, Any]] = None,
 ) -> Dict[str, Any]:
     """Get coerced argument values based on provided definitions and nodes.
 
@@ -221,7 +221,7 @@ def get_argument_values(
 def get_directive_values(
     directive_def: GraphQLDirective,
     node: NodeWithDirective,
-    variable_values: Dict[str, Any] = None,
+    variable_values: Optional[Dict[str, Any]] = None,
 ) -> Optional[Dict[str, Any]]:
     """Get coerced argument values based on provided nodes.
 

src/graphql/graphql.py

@@ -1,6 +1,6 @@
 from asyncio import ensure_future
 from inspect import isawaitable
-from typing import Any, Awaitable, Dict, Union, Type, cast
+from typing import Any, Awaitable, Dict, Optional, Union, Type, cast
 
 from .error import GraphQLError
 from .execution import execute, ExecutionResult, ExecutionContext, Middleware
@@ -21,11 +21,11 @@ async def graphql(
     source: Union[str, Source],
     root_value: Any = None,
     context_value: Any = None,
-    variable_values: Dict[str, Any] = None,
-    operation_name: str = None,
-    field_resolver: GraphQLFieldResolver = None,
-    type_resolver: GraphQLTypeResolver = None,
-    middleware: Middleware = None,
+    variable_values: Optional[Dict[str, Any]] = None,
+    operation_name: Optional[str] = None,
+    field_resolver: Optional[GraphQLFieldResolver] = None,
+    type_resolver: Optional[GraphQLTypeResolver] = None,
+    middleware: Optional[Middleware] = None,
     execution_context_class: Type[ExecutionContext] = ExecutionContext,
 ) -> ExecutionResult:
     """Execute a GraphQL operation asynchronously.
@@ -95,11 +95,11 @@ def graphql_sync(
     source: Union[str, Source],
     root_value: Any = None,
     context_value: Any = None,
-    variable_values: Dict[str, Any] = None,
-    operation_name: str = None,
-    field_resolver: GraphQLFieldResolver = None,
-    type_resolver: GraphQLTypeResolver = None,
-    middleware: Middleware = None,
+    variable_values: Optional[Dict[str, Any]] = None,
+    operation_name: Optional[str] = None,
+    field_resolver: Optional[GraphQLFieldResolver] = None,
+    type_resolver: Optional[GraphQLTypeResolver] = None,
+    middleware: Optional[Middleware] = None,
     execution_context_class: Type[ExecutionContext] = ExecutionContext,
 ) -> ExecutionResult:
     """Execute a GraphQL operation synchronously.

src/graphql/language/ast.py

@@ -93,8 +93,8 @@ def __init__(
         end: int,
         line: int,
         column: int,
-        prev: "Token" = None,
-        value: str = None,
+        prev: Optional["Token"] = None,
+        value: Optional[str] = None,
     ) -> None:
         self.kind = kind
         self.start, self.end = start, end

src/graphql/language/parser.py

@@ -1025,7 +1025,7 @@ def expect_optional_keyword(self, value: str) -> bool:
 
         return False
 
-    def unexpected(self, at_token: Token = None) -> GraphQLError:
+    def unexpected(self, at_token: Optional[Token] = None) -> GraphQLError:
         """Create an error when an unexpected lexed token is encountered."""
         token = at_token or self._lexer.token
         return GraphQLSyntaxError(

src/graphql/language/source.py

@@ -1,3 +1,5 @@
+from typing import Optional
+
 from .location import SourceLocation
 
 __all__ = ["Source"]
@@ -9,7 +11,10 @@ class Source:
     __slots__ = "body", "name", "location_offset"
 
     def __init__(
-        self, body: str, name: str = None, location_offset: SourceLocation = None
+        self,
+        body: str,
+        name: Optional[str] = None,
+        location_offset: Optional[SourceLocation] = None,
     ) -> None:
         """Initialize source input.
 

src/graphql/pyutils/did_you_mean.py

@@ -1,11 +1,11 @@
-from typing import Sequence
+from typing import Optional, Sequence
 
 __all__ = ["did_you_mean"]
 
 MAX_LENGTH = 5
 
 
-def did_you_mean(suggestions: Sequence[str], sub_message: str = None) -> str:
+def did_you_mean(suggestions: Sequence[str], sub_message: Optional[str] = None) -> str:
     """Given [ A, B, C ] return ' Did you mean A, B, or C?'"""
     if not suggestions:
         return ""

src/graphql/subscription/map_async_iterator.py

@@ -1,7 +1,7 @@
 from asyncio import Event, ensure_future, Future, wait
 from concurrent.futures import FIRST_COMPLETED
 from inspect import isasyncgen, isawaitable
-from typing import AsyncIterable, Callable, Set
+from typing import AsyncIterable, Callable, Optional, Set
 
 __all__ = ["MapAsyncIterator"]
 
@@ -21,7 +21,7 @@ def __init__(
         self,
         iterable: AsyncIterable,
         callback: Callable,
-        reject_callback: Callable = None,
+        reject_callback: Optional[Callable] = None,
     ) -> None:
         self.iterator = iterable.__aiter__()
         self.callback = callback

src/graphql/subscription/subscribe.py

@@ -1,5 +1,14 @@
 from inspect import isawaitable
-from typing import Any, AsyncIterable, AsyncIterator, Awaitable, Dict, Union, cast
+from typing import (
+    Any,
+    AsyncIterable,
+    AsyncIterator,
+    Awaitable,
+    Dict,
+    Optional,
+    Union,
+    cast,
+)
 
 from ..error import GraphQLError, located_error
 from ..execution.execute import (
@@ -23,10 +32,10 @@ async def subscribe(
     document: DocumentNode,
     root_value: Any = None,
     context_value: Any = None,
-    variable_values: Dict[str, Any] = None,
-    operation_name: str = None,
-    field_resolver: GraphQLFieldResolver = None,
-    subscribe_field_resolver: GraphQLFieldResolver = None,
+    variable_values: Optional[Dict[str, Any]] = None,
+    operation_name: Optional[str] = None,
+    field_resolver: Optional[GraphQLFieldResolver] = None,
+    subscribe_field_resolver: Optional[GraphQLFieldResolver] = None,
 ) -> Union[AsyncIterator[ExecutionResult], ExecutionResult]:
     """Create a GraphQL subscription.
 
@@ -91,9 +100,9 @@ async def create_source_event_stream(
     document: DocumentNode,
     root_value: Any = None,
     context_value: Any = None,
-    variable_values: Dict[str, Any] = None,
-    operation_name: str = None,
-    field_resolver: GraphQLFieldResolver = None,
+    variable_values: Optional[Dict[str, Any]] = None,
+    operation_name: Optional[str] = None,
+    field_resolver: Optional[GraphQLFieldResolver] = None,
 ) -> Union[AsyncIterable[Any], ExecutionResult]:
     """Create source even stream