Add flake8-bugbear to report potential bugs

Author: Cito

.flake8

@@ -4,3 +4,4 @@
 ignore = E203,W503
 exclude = .git,.mypy_cache,.pytest_cache,.tox,.venv,__pycache__,build,dist,docs
 max-line-length = 88
+per-file-ignores = tests/*:B011

pyproject.toml

@@ -63,6 +63,7 @@ optional = true
 black = "22.8.0"
 flake8 = "^5.0"
 flake8-bandit = "^4.1"
+flake8-bugbear = "22.9.23"
 isort = "^5.10"
 mypy = "0.971"
 bump2version = ">=1.0,<2"

src/graphql/execution/execute.py

@@ -714,7 +714,7 @@ async def await_completed(item: Any, item_path: Path) -> Any:
                         error = located_error(
                             raw_error, field_nodes, item_path.as_list()
                         )
-                        self.handle_field_error(error, item_type)
+                        self.handle_field_error(error, item_type)  # noqa: B023
                         return None
 
                 completed_item = await_completed(item, item_path)
@@ -732,7 +732,7 @@ async def await_completed(item: Any, item_path: Path) -> Any:
                                 error = located_error(
                                     raw_error, field_nodes, item_path.as_list()
                                 )
-                                self.handle_field_error(error, item_type)
+                                self.handle_field_error(error, item_type)  # noqa: B023
                                 return None
 
                         completed_item = await_completed(completed_item, item_path)

src/graphql/execution/values.py

@@ -125,13 +125,15 @@ def on_input_value_error(
             path: List[Union[str, int]], invalid_value: Any, error: GraphQLError
         ) -> None:
             invalid_str = inspect(invalid_value)
-            prefix = f"Variable '${var_name}' got invalid value {invalid_str}"
+            prefix = (
+                f"Variable '${var_name}' got invalid value {invalid_str}"  # noqa: B023
+            )
             if path:
-                prefix += f" at '{var_name}{print_path_list(path)}'"
+                prefix += f" at '{var_name}{print_path_list(path)}'"  # noqa: B023
             on_error(
                 GraphQLError(
                     prefix + "; " + error.message,
-                    var_def_node,
+                    var_def_node,  # noqa: B023
                     original_error=error.original_error,
                 )
             )

src/graphql/language/source.py

@@ -5,6 +5,9 @@
 
 __all__ = ["Source", "is_source"]
 
+DEFAULT_NAME = "GraphQL request"
+DEFAULT_SOURCE_LOCATION = SourceLocation(1, 1)
+
 
 class Source:
     """A representation of source input to GraphQL."""
@@ -15,8 +18,8 @@ class Source:
     def __init__(
         self,
         body: str,
-        name: str = "GraphQL request",
-        location_offset: SourceLocation = SourceLocation(1, 1),
+        name: str = DEFAULT_NAME,
+        location_offset: SourceLocation = DEFAULT_SOURCE_LOCATION,
     ) -> None:
         """Initialize source input.
 

src/graphql/language/visitor.py

@@ -110,7 +110,7 @@ def leave(self, node, key, parent, path, ancestors):
     def __init_subclass__(cls) -> None:
         """Verify that all defined handlers are valid."""
         super().__init_subclass__()
-        for attr, val in cls.__dict__.items():
+        for attr in cls.__dict__:
             if attr.startswith("_"):
                 continue
             attr_kind = attr.split("_", 1)

src/graphql/pyutils/cached_property.py

@@ -22,7 +22,7 @@ class CachedProperty:
         """
 
         def __init__(self, func: Callable) -> None:
-            self.__doc__ = getattr(func, "__doc__")
+            self.__doc__ = func.__doc__
             self.func = func
 
         def __get__(self, obj: object, cls: type) -> Any:

src/graphql/pyutils/identity_func.py

@@ -8,7 +8,9 @@
 
 T = TypeVar("T")
 
+DEFAULT_VALUE = cast(Any, Undefined)
 
-def identity_func(x: T = cast(Any, Undefined), *_args: Any) -> T:
+
+def identity_func(x: T = DEFAULT_VALUE, *_args: Any) -> T:
     """Return the first received argument."""
     return x

tests/language/test_ast.py

@@ -180,18 +180,19 @@ def can_hash():
         assert node3 != node
         assert hash(node3) != hash(node)
 
+    # noinspection PyProtectedMember
     def caches_are_hashed():
         node = SampleTestNode(alpha=1)
         assert not hasattr(node, "_hash")
         hash1 = hash(node)
         assert hasattr(node, "_hash")
-        assert hash1 == getattr(node, "_hash")
+        assert hash1 == node._hash
         node.alpha = 2
         assert not hasattr(node, "_hash")
         hash2 = hash(node)
         assert hash2 != hash1
         assert hasattr(node, "_hash")
-        assert hash2 == getattr(node, "_hash")
+        assert hash2 == node._hash
 
     def can_create_weak_reference():
         node = SampleTestNode(alpha=1, beta=2)

tests/pyutils/test_simple_pub_sub.py

@@ -91,6 +91,6 @@ async def iterator_aclose_is_idempotent():
         pubsub = SimplePubSub()
         iterator = pubsub.get_subscriber()
         assert iterator.listening
-        for n in range(3):
+        for _n in range(3):
             await iterator.aclose()
             assert not iterator.listening