Merge lp:~thomir/unity/wait_for-to-use-testtools-exception into lp:unity

[Thomi Richards]

Extend the autopilot wait_for feature to use testtools matcher instances as well as ordinary values. Also added an 'Eventually' matcher which makes tests more explicit.

We'd like to be able to use testtools.matchers class instances with the new wait_for feature. Currently the wait_for feature allows us to do this:

emulator.attribute.wait_for(expected_value)

Which will wait until 'attribute' is equal to 'expected_value'. We can now extend this to use any testtools matcher object, for example:

emulator.attribute.wait_for(LessThan(123))
 - or -
emulator.attribute.wait_for(In(['several','possible','accepted','values'])

This makes the wait_for feature considerably more powerful.

[Tim Penhey (thumper)]

Given that people can write matchers that are not in the testtools class, I think a better check would be to see if it had the match method.

# Remember hasattr is dangerous.
match_func = getattr(expected_value, 'match', None)
if callable(match_func)...

If expected_value isn't a matcher, make it one by:
  expected_value = Equals(expected_value)
then you don't need to have two code paths inside the time loop.

review: Needs Fixing

[Thomi Richards (thomir)]

Done.

[Alex Launi (alexlauni)]

Looks rad!

review: Approve

[Unity Merger (unity-merger)]

No proposals found for merge of lp:~thomir/unity/autopilot-attribute-feature into lp:unity.

[Tim Penhey (thumper)]

> if not wait_fun:

You shouldn't use a bool check here. What if the object had an attribute called wait_for that returned "foo"?

Instead use:

if wait_fun is None:
  raise...

review: Needs Fixing

[lp:~thomir/unity/wait_for-to-use-testtools-exception]

2237. By Thomi Richards on 2012-04-18

Fixed code from review.

2238. By Thomi Richards on 2012-04-18

Fixed code from review.

2239. By Thomi Richards on 2012-04-18

Check match and wait_for attribute are callables.:

Unmerged revisions

=== added directory 'tests/autopilot/autopilot/matchers'
=== added file 'tests/autopilot/autopilot/matchers/__init__.py'
--- tests/autopilot/autopilot/matchers/__init__.py	1970-01-01 00:00:00 +0000
+++ tests/autopilot/autopilot/matchers/__init__.py	2012-04-17 21:23:20 +0000
@@ -0,0 +1,31 @@
+# -*- Mode: Python; coding: utf-8; indent-tabs-mode: nil; tab-width: 4 -*-
+# Copyright 2012 Canonical
+# Author: Thomi Richards
+#
+# This program is free software: you can redistribute it and/or modify it
+# under the terms of the GNU General Public License version 3, as published
+# by the Free Software Foundation.
+
+"Autopilot-specific matchers."
+
+from testtools.matchers import Matcher
+
+
+class Eventually(Matcher):
+    """Asserts that a value will eventually equal a given Matcher object."""
+
+    def __init__(self, matcher):
+        super(Eventually, self).__init__()
+        match_fun = getattr(matcher, 'match', None)
+        if not match_fun:
+            raise TypeError("Eventually must be called with a testtools matcher argument.")
+        self.matcher = matcher
+
+    def match(self, value):
+        wait_fun = getattr(value, 'wait_for', None)
+        if not wait_fun:
+            raise TypeError("Eventually can only be used against autopilot attributes that have a wait_for funtion.")
+        value.wait_for(self.matcher)
+
+    def __str__(self):
+        return "Eventually " + str(self.matcher)