rulesets/python_bugbear.yaml at main · sylver-dev/rulesets · GitHub

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id: python_bugbear

language: python

rules:
    - id: prefix_increment
      category: smell
      message: "unary increment is not supported"

      note: "Python does not support the unary prefix increment. Writing ++n is equivalent to +(+(n)),
        which equals n. You meant n += 1."

      query: >
        match UnaryOperator(
          operator: Add,
          argument: UnaryOperator(operator: Add, argument: Identifier)
        )


    - id: os_environ_assign
      category: smell
      message: "assignment to os.environ"

      note: "Assigning to os.environ doesn't clear the environment. Subprocesses are going to see outdated
        variables, in disagreement with the current process. Use os.environ.clear() or the env= argument to Popen."

      query: >
        match Assignment(left: Subscript(value: 'os.environ'))


    - id: strip_multichar
      category: smell
      message: "call to .strip() with a multi-character string"

      note: "Using .strip() with multi-character strings is misleading the reader. It looks like stripping a
        substring. Move your character set to a constant if this is deliberate. Use .replace() or
        regular expressions to remove string fragments."

      query: >
        match c@Call(function: Attribute(attribute: 'strip')) when
          c.arguments.children.length == 1
          && c.arguments.children[0] is String
          && c.arguments.children[0].text.length > 3


    - id: assert_false
      category: smell
      message: "assert False"

      note: "Do not assert False (python -O removes these calls), raise AssertionError()"

      query: >
        match a@AssertStatement when a.children.length == 1 && a.children[0] is False


    - id: pointless_comparison
      category: smell
      message: "pointless comparison"

      note: "Pointless comparison. This comparison does nothing but waste CPU instructions.
        Either prepend assert or remove it."

      query: >
        match c@ComparisonOperator when c.parent is
          ExpressionStatement
          && (c.parent.parent is Module || c.parent.parent is Block)


    - id: assertRaises_Exception
      category: smell
      message: "assertRaises(Exception) should be considered evil"

      note: "assertRaises(Exception): should be considered evil. It can lead to your test passing even if the
        code being tested is never executed due to a typo. Either assert for a more specific exception
        (builtin or custom), use assertRaisesRegex, or use the context manager form of assertRaises."

      query: >
        match c@Call(function: Attribute(attribute: 'assertRaises')) when
          c.arguments.children.length == 1
          && c.arguments.children[0].text == 'Exception'


    - id: pointless_contextlib_suppress
      category: smell
      message: "not argument passed to contextlib.suppress"

      note: "No arguments passed to contextlib.suppress. No exceptions will be suppressed and therefore
        this context manager is redundant"

      query: >
        match c@Call when c.function.text.matches(`(contextlib\.)?suppress`)
          && c.parent is WithItem
          && c.arguments.children.length == 0


    - id: star_arg_unpacking_after_keyword_arg
      category: smell
      message: "star-arg unpacking after a keyword argument is discouraged"

      note: "Star-arg unpacking after a keyword argument is strongly discouraged, because it only works when
        the keyword parameter is declared after all parameters supplied by the unpacked sequence, and
        this change of ordering can surprise and mislead readers"

      query: >
        match l@ListSplat when l.previous_sibling is KeywordArgument