Add B044: assert <generator_expression>

Author: gschaffner

README.rst

@@ -304,6 +304,10 @@ If you define `__str__/__reduce__` in super classes this check is unable to dete
 **B043**: Do not call ``delattr(x, 'attr')``, instead use ``del x.attr``. 
 There is no additional safety in using ``delattr`` if you know the attribute name ahead of time.
 
+.. _B044:
+
+**B044**: `assert <generator_expression>` is always true. Did you forget `all()`?
+
 
 Opinionated warnings
 ~~~~~~~~~~~~~~~~~~~~
@@ -494,6 +498,11 @@ MIT
 Change Log
 ----------
 
+UNRELEASED
+~~~~~~~~~~
+
+* B044: New check for `assert <generator_expression>`, which is always true (#534)
+
 25.11.29
 ~~~~~~~~
 

bugbear.py

@@ -622,6 +622,7 @@ def visit_GeneratorExp(self, node: ast.GeneratorExp) -> None:
 
     def visit_Assert(self, node: ast.Assert) -> None:
         self.check_for_b011(node)
+        self.check_for_b044(node)
         self.generic_visit(node)
 
     def visit_AsyncFunctionDef(self, node: ast.AsyncFunctionDef) -> None:
@@ -1887,6 +1888,10 @@ def is_exception(s: str):
                 return
         # no `def __init__` found, which is fine
 
+    def check_for_b044(self, node: ast.Assert) -> None:
+        if isinstance(node.test, ast.GeneratorExp):
+            self.add_error("B044", node)
+
     def check_for_b909(self, node: ast.For) -> None:
         if isinstance(node.iter, ast.Name):
             name = _to_name_str(node.iter)
@@ -2521,6 +2526,11 @@ def __call__(self, lineno: int, col: int, vars: tuple[object, ...] = ()) -> erro
             "it is not any safer than normal property access."
         )
     ),
+    "B044": Error(
+        message=(
+            "B044 `assert <generator_expression>` is always true. Did you forget `all()`?"
+        )
+    ),
     # Warnings disabled by default.
     "B901": Error(
         message=(

tests/eval_files/b044.py

@@ -0,0 +1,4 @@
+assert (x for x in a)  # B044: 0
+assert [x for x in a]
+assert {x for x in a}
+assert {x: y for x, y in a}