Clean up tests and examples for Python 3.4

This addresses some of the feedback in
I71c0bb61c9ee0bf1b751a719a4eb95bf7a0b4943

Change-Id: Ie916ebda1ddff6de528a495bf249d40e7b1e7fc5

bandit/core/context.py

@@ -16,6 +16,8 @@
 
 import _ast
 
+import six
+
 from bandit.core import utils
 
 
@@ -184,10 +186,6 @@ class Context():
         elif isinstance(literal, _ast.Str):
             return literal.s
 
-        # Python 3 only
-        # elif isinstance(literal, _ast.Bytes):
-        #    return literal.s
-
         elif isinstance(literal, _ast.List):
             return_list = list()
             for li in literal.elts:
@@ -213,16 +211,19 @@ class Context():
             # what do we want to do with this?
             pass
 
-        # Python 3 only
-        # elif isinstance(literal, _ast.NameConstant):
-        #    return literal.value
-
         elif isinstance(literal, _ast.Name):
             return literal.id
 
-        elif hasattr(literal, 'value'):
+        # NOTE(sigmavirus24): NameConstants are only part of the AST in Python
+        # 3. NameConstants tend to refer to things like True and False. This
+        # prevents them from being re-assigned in Python 3.
+        elif six.PY3 and isinstance(literal, _ast.NameConstant):
             return str(literal.value)
 
+        # NOTE(sigmavirus24): Bytes are only part of the AST in Python 3
+        elif six.PY3 and isinstance(literal, _ast.Bytes):
+            return literal.s
+
         else:
             return None
 

examples/exec-py3.py

@@ -0,0 +1 @@
+exec("do evil")

examples/os-chmod-py3.py

@@ -0,0 +1,17 @@
+import os
+import stat
+
+keyfile = 'foo'
+
+os.chmod('/etc/passwd', 0o227)
+os.chmod('/etc/passwd', 0o7)
+os.chmod('/etc/passwd', 0o664)
+os.chmod('/etc/passwd', 0o777)
+os.chmod('/etc/passwd', 0o770)
+os.chmod('/etc/passwd', 0o776)
+os.chmod('/etc/passwd', 0o760)
+os.chmod('~/.bashrc', 511)
+os.chmod('/etc/hosts', 0o777)
+os.chmod('/tmp/oh_hai', 0x1ff)
+os.chmod('/etc/passwd', stat.S_IRWXU)
+os.chmod(key_file, 0o777)

tests/test_functional.py

@@ -19,6 +19,8 @@ import os
 import unittest
 import inspect
 
+import six
+
 from bandit.core import constants as C
 from bandit.core import manager as b_manager
 from bandit.core import test_set as b_test_set
@@ -100,8 +102,14 @@ class FunctionalTests(unittest.TestCase):
 
     def test_exec(self):
         '''Test the `exec` example.'''
-        expect = {'SEVERITY': {'MEDIUM': 2}, 'CONFIDENCE': {'HIGH': 2}}
-        self.check_example('exec.py', expect)
+        filename = 'exec-{}.py'
+        if six.PY2:
+            filename = filename.format('py2')
+            expect = {'SEVERITY': {'MEDIUM': 2}, 'CONFIDENCE': {'HIGH': 2}}
+        else:
+            filename = filename.format('py3')
+            expect = {'SEVERITY': {'MEDIUM': 1}, 'CONFIDENCE': {'HIGH': 1}}
+        self.check_example(filename, expect)
 
     def test_exec_as_root(self):
         '''Test for the `run_as_root=True` keyword argument.'''
@@ -173,10 +181,19 @@ class FunctionalTests(unittest.TestCase):
 
     def test_os_chmod(self):
         '''Test setting file permissions.'''
-        expect = {
-            'SEVERITY': {'MEDIUM': 2, 'HIGH': 9},
-            'CONFIDENCE': {'HIGH': 10, 'MEDIUM': 1}
-        }
+        filename = 'os-chmod-{}.py'
+        if six.PY2:
+            filename = filename.format('py2')
+            expect = {
+                'SEVERITY': {'MEDIUM': 2, 'HIGH': 9},
+                'CONFIDENCE': {'HIGH': 10, 'MEDIUM': 1}
+            }
+        else:
+            filename = filename.format('py3')
+            expect = {
+                'SEVERITY': {'MEDIUM': 2, 'HIGH': 9},
+                'CONFIDENCE': {'HIGH': 10, 'MEDIUM': 1}
+            }
         self.check_example('os-chmod.py', expect)
 
     def test_os_exec(self):