Source code for keystone.hacking.checks

# Licensed under the Apache License, Version 2.0 (the "License"); you may
# not use this file except in compliance with the License. You may obtain
# a copy of the License at
#
#      http://www.apache.org/licenses/LICENSE-2.0
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"""Keystone's pep8 extensions.

In order to make the review process faster and easier for core devs we are
adding some Keystone specific pep8 checks. This will catch common errors
so that core devs don't have to.

There are two types of pep8 extensions. One is a function that takes either
a physical or logical line. The physical or logical line is the first param
in the function definition and can be followed by other parameters supported
by pep8. The second type is a class that parses AST trees. For more info
please see pep8.py.
"""

import ast

import six


[docs]class BaseASTChecker(ast.NodeVisitor): """Provides a simple framework for writing AST-based checks. Subclasses should implement visit_* methods like any other AST visitor implementation. When they detect an error for a particular node the method should call ``self.add_error(offending_node)``. Details about where in the code the error occurred will be pulled from the node object. Subclasses should also provide a class variable named CHECK_DESC to be used for the human readable error message. """ def __init__(self, tree, filename): """This object is created automatically by pep8. :param tree: an AST tree :param filename: name of the file being analyzed (ignored by our checks) """ self._tree = tree self._errors = []
[docs] def run(self): """Called automatically by pep8.""" self.visit(self._tree) return self._errors
[docs] def add_error(self, node, message=None): """Add an error caused by a node to the list of errors for pep8.""" message = message or self.CHECK_DESC error = (node.lineno, node.col_offset, message, self.__class__) self._errors.append(error)
[docs]class CheckForMutableDefaultArgs(BaseASTChecker): """Checks for the use of mutable objects as function/method defaults. We are only checking for list and dict literals at this time. This means that a developer could specify an instance of their own and cause a bug. The fix for this is probably more work than it's worth because it will get caught during code review. """ CHECK_DESC = 'K001 Using mutable as a function/method default' # TODO(dstanek): once we drop support for Python 2.6 we can add ast.Set, # ast.DictComp and ast.SetComp to MUTABLES. Don't forget the tests! MUTABLES = (ast.List, ast.ListComp, ast.Dict)
[docs] def visit_FunctionDef(self, node): for arg in node.args.defaults: if isinstance(arg, self.MUTABLES): self.add_error(arg) super(CheckForMutableDefaultArgs, self).generic_visit(node)
[docs]def block_comments_begin_with_a_space(physical_line, line_number): """There should be a space after the # of block comments. There is already a check in pep8 that enforces this rule for inline comments. Okay: # this is a comment Okay: #!/usr/bin/python Okay: # this is a comment K002: #this is a comment """ MESSAGE = "K002 block comments should start with '# '" # shebangs are OK if line_number == 1 and physical_line.startswith('#!'): return text = physical_line.strip() if text.startswith('#'): # look for block comments if len(text) > 1 and not text[1].isspace(): return physical_line.index('#'), MESSAGE
[docs]class CheckForAssertingNoneEquality(BaseASTChecker): """Ensures that code does not use a None with assert(Not*)Equal.""" CHECK_DESC_IS = ('K003 Use self.assertIsNone(...) when comparing ' 'against None') CHECK_DESC_ISNOT = ('K004 Use assertIsNotNone(...) when comparing ' ' against None')
[docs] def visit_Call(self, node): # NOTE(dstanek): I wrote this in a verbose way to make it easier to # read for those that have little experience with Python's AST. if isinstance(node.func, ast.Attribute): if node.func.attr == 'assertEqual': for arg in node.args: if isinstance(arg, ast.Name) and arg.id == 'None': self.add_error(node, message=self.CHECK_DESC_IS) elif node.func.attr == 'assertNotEqual': for arg in node.args: if isinstance(arg, ast.Name) and arg.id == 'None': self.add_error(node, message=self.CHECK_DESC_ISNOT) super(CheckForAssertingNoneEquality, self).generic_visit(node)
[docs]class CheckForTranslationsInDebugLogging(BaseASTChecker): CHECK_DESC = 'K005 Using translated string in debug logging' LOG_MODULES = ('logging', 'keystone.openstack.common.log') I18N_MODULES = ('keystone.i18n._') def __init__(self, tree, filename): super(CheckForTranslationsInDebugLogging, self).__init__( tree, filename) self.logger_names = [] self.logger_module_names = [] self.i18n_names = [] # NOTE(dstanek): this kinda accounts for scopes when talking # about only leaf node in the graph self.assignments = [] def _filter_imports(self, module_name, alias): """Keeps lists of logging and i18n imports """ if module_name in self.LOG_MODULES: self.logger_module_names.append(alias.asname or alias.name) elif module_name in self.I18N_MODULES: self.i18n_names.append(alias.asname or alias.name)
[docs] def visit_Import(self, node): for alias in node.names: self._filter_imports(alias.name, alias) super(CheckForTranslationsInDebugLogging, self).generic_visit(node)
[docs] def visit_ImportFrom(self, node): for alias in node.names: full_name = '%s.%s' % (node.module, alias.name) self._filter_imports(full_name, alias) super(CheckForTranslationsInDebugLogging, self).generic_visit(node)
def _find_name(self, node): """Return the fully qualified name or a Name or Attribute.""" if isinstance(node, ast.Name): return node.id elif (isinstance(node, ast.Attribute) and isinstance(node.value, (ast.Name, ast.Attribute))): method_name = node.attr obj_name = self._find_name(node.value) if obj_name is None: return None return obj_name + '.' + method_name elif isinstance(node, six.string_types): return node else: # could be Subscript, Call or many more return None
[docs] def visit_Assign(self, node): """Look for 'LOG = logging.getLogger' This only handles the simple case: name = [logging_module].getLogger(...) - or - name = [i18n_name](...) """ attr_node_types = (ast.Name, ast.Attribute) if (len(node.targets) != 1 or not isinstance(node.targets[0], attr_node_types)): # say no to: "x, y = ..." return target_name = self._find_name(node.targets[0]) if not isinstance(node.value, ast.Call): # node.value must be a call to getLogger return # is this a call to an i18n function? if (isinstance(node.value.func, ast.Name) and node.value.func.id in self.i18n_names): self.assignments.append(target_name) return if (not isinstance(node.value.func, ast.Attribute) or not isinstance(node.value.func.value, attr_node_types)): # function must be an attribute on an object like # logging.getLogger return object_name = self._find_name(node.value.func.value) func_name = node.value.func.attr if (object_name in self.logger_module_names and func_name == 'getLogger'): self.logger_names.append(target_name)
[docs] def visit_Call(self, node): """Look for the 'LOG.debug' calls. """ # obj.method if isinstance(node.func, ast.Attribute): obj_name = self._find_name(node.func.value) if isinstance(node.func.value, ast.Name): method_name = node.func.attr elif isinstance(node.func.value, ast.Attribute): obj_name = self._find_name(node.func.value) method_name = node.func.attr else: # could be Subscript, Call or many more return # must be a logger instance and the debug method if obj_name not in self.logger_names or method_name != 'debug': return # the call must have arguments if not len(node.args): return # if first arg is a call to a i18n name if (isinstance(node.args[0], ast.Call) and isinstance(node.args[0].func, ast.Name) and node.args[0].func.id in self.i18n_names): self.add_error(node.args[0]) # if the first arg is a reference to a i18n call elif (isinstance(node.args[0], ast.Name) and node.args[0].id in self.assignments): self.add_error(node.args[0])
[docs]def factory(register): register(CheckForMutableDefaultArgs) register(block_comments_begin_with_a_space) register(CheckForAssertingNoneEquality) register(CheckForTranslationsInDebugLogging)