Allow rules to correct commands that time out

tests/test_main.py

@@ -14,7 +14,8 @@ def test_load_rule(mocker):
         return_value=Mock(match=match,
                           get_new_command=get_new_command,
                           enabled_by_default=True,
-                          priority=900))
+                          priority=900,
+                          requires_output=True))
     assert main.load_rule(Path('/rules/bash.py')) \
            == Rule('bash', match, get_new_command, priority=900)
     load_source.assert_called_once_with('bash', '/rules/bash.py')

tests/utils.py

@@ -10,7 +10,8 @@ def Rule(name='', match=lambda *_: True,
          get_new_command=lambda *_: '',
          enabled_by_default=True,
          side_effect=None,
-         priority=DEFAULT_PRIORITY):
+         priority=DEFAULT_PRIORITY,
+         requires_output=True):
     return types.Rule(name, match, get_new_command,
                       enabled_by_default, side_effect,
-                      priority)
+                      priority, requires_output)