coverage: Clearly mark not reachable places in the code

Replicates graphql/graphql-js@635a13c

Author: Cito

src/graphql/utilities/lexicographic_sort_schema.py

@@ -93,28 +93,28 @@ def sort_types(arr: FrozenList[GraphQLNamedType]) -> List[GraphQLNamedType]:
     def sort_named_type(type_: GraphQLNamedType) -> GraphQLNamedType:
         if is_scalar_type(type_) or is_introspection_type(type_):
             return type_
-        elif is_object_type(type_):
+        if is_object_type(type_):
             kwargs = type_.to_kwargs()
             type_ = cast(GraphQLObjectType, type_)
             kwargs.update(
                 interfaces=lambda: sort_types(type_.interfaces),
                 fields=lambda: sort_fields(type_.fields),
             )
             return GraphQLObjectType(**kwargs)
-        elif is_interface_type(type_):
+        if is_interface_type(type_):
             kwargs = type_.to_kwargs()
             type_ = cast(GraphQLInterfaceType, type_)
             kwargs.update(
                 interfaces=lambda: sort_types(type_.interfaces),
                 fields=lambda: sort_fields(type_.fields),
             )
             return GraphQLInterfaceType(**kwargs)
-        elif is_union_type(type_):
+        if is_union_type(type_):
             kwargs = type_.to_kwargs()
             type_ = cast(GraphQLUnionType, type_)
             kwargs.update(types=lambda: sort_types(type_.types))
             return GraphQLUnionType(**kwargs)
-        elif is_enum_type(type_):
+        if is_enum_type(type_):
             kwargs = type_.to_kwargs()
             type_ = cast(GraphQLEnumType, type_)
             kwargs.update(
@@ -129,7 +129,7 @@ def sort_named_type(type_: GraphQLNamedType) -> GraphQLNamedType:
                 }
             )
             return GraphQLEnumType(**kwargs)
-        elif is_input_object_type(type_):
+        if is_input_object_type(type_):
             kwargs = type_.to_kwargs()
             type_ = cast(GraphQLInputObjectType, type_)
             kwargs.update(fields=lambda: sort_input_fields(type_.fields))

src/graphql/utilities/schema_printer.py

@@ -140,6 +140,7 @@ def print_type(type_: GraphQLNamedType) -> str:
     if is_input_object_type(type_):
         type_ = cast(GraphQLInputObjectType, type_)
         return print_input_object(type_)
+
     # Not reachable. All possible types have been considered.
     raise TypeError(f"Unexpected type: {inspect(type_)}.")  # pragma: no cover
 

src/graphql/utilities/type_info.py

@@ -10,7 +10,6 @@
     Node,
     ObjectFieldNode,
     OperationDefinitionNode,
-    OperationType,
     SelectionSetNode,
     VariableDefinitionNode,
     Visitor,
@@ -157,14 +156,7 @@ def enter_directive(self, node: DirectiveNode):
         self._directive = self._schema.get_directive(node.name.value)
 
     def enter_operation_definition(self, node: OperationDefinitionNode):
-        if node.operation == OperationType.QUERY:
-            type_ = self._schema.query_type
-        elif node.operation == OperationType.MUTATION:
-            type_ = self._schema.mutation_type
-        elif node.operation == OperationType.SUBSCRIPTION:
-            type_ = self._schema.subscription_type
-        else:
-            type_ = None
+        type_ = getattr(self._schema, f"{node.operation.value}_type")
         self._type_stack.append(type_ if is_object_type(type_) else None)
 
     def enter_inline_fragment(self, node: InlineFragmentNode):

src/graphql/validation/rules/known_directives.py

@@ -95,7 +95,7 @@ def get_directive_location_for_ast_path(ancestors):
         kind = applied_to.kind
         if kind == "operation_definition":
             applied_to = cast(OperationDefinitionNode, applied_to)
-            return _operation_location.get(applied_to.operation.value)
+            return _operation_location[applied_to.operation.value]
         elif kind == "input_value_definition":
             parent_node = ancestors[-3]
             return (

src/graphql/validation/rules/possible_type_extensions.py

@@ -4,7 +4,7 @@
 
 from ...error import GraphQLError
 from ...language import TypeDefinitionNode, TypeExtensionNode
-from ...pyutils import did_you_mean, suggestion_list
+from ...pyutils import did_you_mean, inspect, suggestion_list
 from ...type import (
     is_enum_type,
     is_input_object_type,
@@ -80,18 +80,19 @@ def check_extension(self, node: TypeExtensionNode, *_args):
 def type_to_ext_kind(type_: Any) -> str:
     if is_scalar_type(type_):
         return "scalar_type_extension"
-    elif is_object_type(type_):
+    if is_object_type(type_):
         return "object_type_extension"
-    elif is_interface_type(type_):
+    if is_interface_type(type_):
         return "interface_type_extension"
-    elif is_union_type(type_):
+    if is_union_type(type_):
         return "union_type_extension"
-    elif is_enum_type(type_):
+    if is_enum_type(type_):
         return "enum_type_extension"
-    elif is_input_object_type(type_):
+    if is_input_object_type(type_):
         return "input_object_type_extension"
-    else:
-        return "unknown_type_extension"
+
+    # Not reachable. All possible types have been considered.
+    raise TypeError(f"Unexpected type: {inspect(type_)}.")  # pragma: no cover
 
 
 _type_names_for_extension_kinds = {

tests/execution/test_abstract.py

@@ -40,7 +40,7 @@ def is_type_of(obj, _info):
 
 def get_type_resolver(types):
     def resolve(obj, _info, _type):
-        return resolve_thunk(types).get(obj.__class__)
+        return resolve_thunk(types)[obj.__class__]
 
     return resolve
 

tests/execution/test_abstract_async.py

@@ -46,7 +46,7 @@ async def is_type_of(obj, _info):
 
 def get_type_resolver(types):
     async def resolve(obj, _info, _type):
-        return resolve_thunk(types).get(obj.__class__)
+        return resolve_thunk(types)[obj.__class__]
 
     return resolve
 

tests/execution/test_union_interface.py

@@ -112,6 +112,9 @@ def resolve_pet_type(value, _info, _type):
     if isinstance(value, Cat):
         return CatType
 
+    # Not reachable. All possible types have been considered.
+    raise TypeError  # pragma: no cover
+
 
 PetType = GraphQLUnionType("Pet", [DogType, CatType], resolve_type=resolve_pet_type)
 

tests/star_wars_schema.py

@@ -116,7 +116,7 @@
     resolve_type=lambda character, _info, _type: {
         "Human": human_type,
         "Droid": droid_type,
-    }.get(character.type),
+    }[character.type],
     description="A character in the Star Wars Trilogy",
 )