add better loop support to common_test.py

Merge from trunk revisions 2976 and 2980

Add better support for looping over a tests[] array to common_test.py:
- class AATest - a base class we can use for all tests, and that will
  probably get more features in the future (for example tempdir
  handling)
- setup_all_tests() - a function that iterates over all classes in the
  given file and calls setup_test_loops() for each of them
- setup_tests_loop() - a function that creates tests based on tests[]
  in the given class. Those tests call the class' _run_test() method for
  each test specified in tests[]  (inspired by setup_regex_tests() ;-)

This means we can get rid of the manually maintained tests list in
test-regex_matches.py and just need to call setup_all_tests() once in
each file.

The patch also adds test-example.py, which is
- a demo of the code added to common_test.py
- a template file that we can copy for future test-*.py

Acked-by: Steve Beattie <steve@nxnw.org>

utils/test/common_test.py

@@ -1,5 +1,6 @@
 # ----------------------------------------------------------------------
 #    Copyright (C) 2013 Kshitij Gupta <kgupta8592@gmail.com>
+#    Copyright (C) 2015 Christian Boltz <apparmor@cboltz.de>
 #
 #    This program is free software; you can redistribute it and/or
 #    modify it under the terms of version 2 of the GNU General Public
@@ -12,8 +13,10 @@
 #
 # ----------------------------------------------------------------------
 import unittest
+import inspect
 import os
 import re
+import sys
 
 import apparmor.common
 import apparmor.config
@@ -34,6 +37,10 @@ class Test(unittest.TestCase):
     #    print("Please press the Y button on the keyboard.")
     #    self.assertEqual(apparmor.common.readkey().lower(), 'y', 'Error reading key from shell!')
 
+
+class AATest(unittest.TestCase):
+    tests = []
+
 class AAParseTest(unittest.TestCase):
     parse_function = None
 
@@ -44,6 +51,33 @@ class AAParseTest(unittest.TestCase):
             'parse object %s returned "%s", expected "%s"' \
             %(self.parse_function.__doc__, parsed.serialize(), rule))
 
+
+def setup_all_tests():
+    '''call setup_tests_loop() for each class in module_name'''
+    for name, obj in inspect.getmembers(sys.modules['__main__']):
+        if inspect.isclass(obj):
+            if issubclass(obj, unittest.TestCase):
+                setup_tests_loop(obj)
+
+def setup_tests_loop(test_class):
+    '''Create tests in test_class using test_class.tests and self._run_test()
+
+    test_class.tests should be tuples of (test_data, expected_results)
+    test_data and expected_results can be of any type as long as test_class._run_test()
+    know how to handle them.
+
+    A typical definition for _run_test() is:
+        def test_class._run_test(self, test_data, expected)
+        '''
+
+    for (i, (test_data, expected)) in enumerate(test_class.tests):
+        def stub_test(self, test_data=test_data, expected=expected):
+            self._run_test(test_data, expected)
+
+        stub_test.__doc__ = "test '%s'" % (test_data)
+        setattr(test_class, 'test_%d' % (i), stub_test)
+
+
 def setup_regex_tests(test_class):
     '''Create tests in test_class using test_class.tests and AAParseTest._test_parse_rule()