Add useful constructors for Rule and Command for tests

tests/utils.py

@@ -0,0 +1,11 @@
+from thefuck import types
+
+
+def Command(script='', stdout='', stderr=''):
+    return types.Command(script, stdout, stderr)
+
+
+def Rule(name='', match=lambda *_: True,
+         get_new_command=lambda *_: '',
+         enabled_by_default=True):
+    return types.Rule(name, match, get_new_command, enabled_by_default)