Issue 1974

CHANGELOG.md

@@ -22,6 +22,7 @@ Semantic versioning in our case means:
 ### Bugfixes
 
 - Fixes `UselessReturningElseViolation` to not report `else` with `break` #1958
+- Fixes bare raise outside of except block #1974
 
 ### Misc
 

tests/fixtures/noqa/noqa.py

@@ -788,3 +788,20 @@ def get_item():  # noqa: WPS463
    some(number) for numbers in matrix
    for number in numbers # noqa: WPS361
 ]
+
+def detect_bare_raise1():
+    """Function to check if the bare raise is detected."""
+    raise
+
+def detect_bare_raise2_helper():
+    """Function to check if the bare raise is detected."""
+    raise ZeroDivisionError
+
+def detect_bare_raise2():
+    """Function to check if the bare raise is detected."""
+    try:
+        testvar = 1/0  # noqa: WPS344, F841
+    except ZeroDivisionError:
+        detect_bare_raise2()
+        raise ZeroDivisionError
+

tests/test_checker/test_noqa.py

@@ -279,6 +279,7 @@
     'WPS529': 1,
     'WPS530': 1,
     'WPS531': 1,
+    'WPS532': 1,
 
     'WPS600': 1,
     'WPS601': 1,

tests/test_visitors/test_ast/test_keywords/test_raise.py

@@ -4,6 +4,7 @@
     BaseExceptionRaiseViolation,
     RaiseNotImplementedViolation,
 )
+from wemake_python_styleguide.violations.refactoring import BareRaiseViolation
 from wemake_python_styleguide.visitors.ast.keywords import WrongRaiseVisitor
 
 raise_exception_method = """
@@ -130,3 +131,22 @@ def test_bare_raise(
     visitor.run()
 
     assert_errors(visitor, [])
+
+
+def test_bare_raise_no_except(
+    assert_errors,
+    parse_ast_tree,
+    default_options,
+):
+    """Testing that bare `raise` is not allowed without an except block."""
+    code = """
+    def hello():
+        raise
+    hello()
+    """
+    tree = parse_ast_tree(code)
+
+    visitor = WrongRaiseVisitor(default_options, tree=tree)
+    visitor.run()
+
+    assert_errors(visitor, [BareRaiseViolation])

wemake_python_styleguide/logic/safe_eval.py

@@ -14,7 +14,6 @@ def _convert_num(node: Optional[ast.AST]):
     elif isinstance(node, ast.Name):
         # We return string names as is, see how we return strings:
         return node.id
-    raise ValueError('malformed node or string: {0!r}'.format(node))
 
 
 def _convert_signed_num(node: Optional[ast.AST]):

wemake_python_styleguide/violations/refactoring.py

@@ -45,6 +45,7 @@
    ImplicitDictGetViolation
    ImplicitNegativeIndexViolation
    SimplifiableReturningIfViolation
+   BareRaiseViolation
 
 Refactoring opportunities
 -------------------------
@@ -81,7 +82,7 @@
 .. autoclass:: ImplicitDictGetViolation
 .. autoclass:: ImplicitNegativeIndexViolation
 .. autoclass:: SimplifiableReturningIfViolation
-
+.. autoclass:: BareRaiseViolation
 """
 
 from typing_extensions import final
@@ -1233,3 +1234,37 @@ def some_function():
 
     error_template = 'Found simplifiable returning `if` condition in a function'
     code = 531
+
+
+@final
+class BareRaiseViolation(ASTViolation):
+    """
+    Forbid bare ``raise`` outside of ``except`` block.
+
+    Reasoning:
+        One could call a function from an ``except`` and have
+        a bare ``raise`` inside but it is considered bad practice
+        to have a bare ``raise`` outside of an ``except`` block.
+
+    Solution:
+        Use a ``raise`` statement inside a parent ``except`` block.
+
+    Example::
+
+        # good
+        def smth():
+            try:
+                ...
+            except:
+                raise
+
+        # bad
+        def smth():
+            raise
+
+    .. versionadded:: 0.15.3
+
+    """
+
+    error_template = 'Bare raise outside of except block detected'
+    code = 532

wemake_python_styleguide/visitors/ast/keywords.py

@@ -32,6 +32,7 @@
     IncorrectYieldFromTargetViolation,
     MultipleContextManagerAssignmentsViolation,
 )
+from wemake_python_styleguide.violations.refactoring import BareRaiseViolation
 from wemake_python_styleguide.visitors.base import BaseNodeVisitor
 from wemake_python_styleguide.visitors.decorators import alias
 
@@ -57,9 +58,11 @@ def visit_Raise(self, node: ast.Raise) -> None:
 
         Raises:
             RaiseNotImplementedViolation
+            BareRaiseViolation
 
         """
         self._check_exception_type(node)
+        self._check_bare_raise(node)
         self.generic_visit(node)
 
     def _check_exception_type(self, node: ast.Raise) -> None:
@@ -71,6 +74,11 @@ def _check_exception_type(self, node: ast.Raise) -> None:
                 BaseExceptionRaiseViolation(node, text=exception_name),
             )
 
+    def _check_bare_raise(self, node: ast.Raise) -> None:
+        parent = walk.get_closest_parent(node, ast.ExceptHandler)
+        if not parent and node.exc is None:
+            self.add_violation(BareRaiseViolation(node))
+
 
 @final
 @alias('visit_any_function', (