Implement checks for raising messages with exceptions (#1113)

* Implement checks for messages being raised with exceptions
(Fixes #1080)

* Add self.assertRaisesWithMessage method to relevant exercise tests
    - Uses self.assertRaisesRegex
    - Checks only for the presence of a message, not content
* Add meaningful messages to failing examples
* octal: Switch to using a context manager for exception tests

* Add note regarding error messages to the insert

* simple-linked-list: Move hints.md to correct location

* simple-cipher: Remove extra whitespace from lines

* collatz-conjecture: Update hints.md

* Regenerate README to include exceptions section

exercises/binary/binary_test.py

@@ -32,21 +32,31 @@ class BinaryTests(unittest.TestCase):
         self.assertEqual(parse_binary("10001101000"), 1128)
 
     def test_invalid_binary_text_only(self):
-        with self.assertRaises(ValueError):
+        with self.assertRaisesWithMessage(ValueError):
             parse_binary("carrot")
 
     def test_invalid_binary_number_not_base2(self):
-        with self.assertRaises(ValueError):
+        with self.assertRaisesWithMessage(ValueError):
             parse_binary("102011")
 
     def test_invalid_binary_numbers_with_text(self):
-        with self.assertRaises(ValueError):
+        with self.assertRaisesWithMessage(ValueError):
             parse_binary("10nope")
 
     def test_invalid_binary_text_with_numbers(self):
-        with self.assertRaises(ValueError):
+        with self.assertRaisesWithMessage(ValueError):
             parse_binary("nope10")
 
+    # Utility functions
+    def setUp(self):
+        try:
+            self.assertRaisesRegex = self.assertRaisesRegexp
+        except AttributeError:
+            pass
+
+    def assertRaisesWithMessage(self, exception):
+        return self.assertRaisesRegex(exception, r".+")
+
 
 if __name__ == '__main__':
     unittest.main()