chromium-cq-status: StatsTest utility class for testing CQ stats

chromium-cq-status: StatsTest utility class for testing CQ stats

This change adds a testing utility class StatsTest.
This class provides two helper functions, one for clearing all Records
and one for importing Records from the contents of a JSON test resource file.
New stats analysis tests will subclass StatsTest to make use of these
helper functions.

[alancutter (OOO until 2018), 2014-08-28 11:57:56]

alancutter@chromium.org changed reviewers:
+ eseidel@chromium.org, jam@chromium.org, sergeyberezin@chromium.org

[eseidel1, 2014-08-28 16:46:32]

eseidel@google.com changed reviewers:
+ eseidel@google.com

[eseidel1, 2014-08-28 16:46:32]

We shouldn't be adding new no covers.

[Sergey Berezin, 2014-08-28 21:14:15]

LGTM + comment (more a question - I'm not clear on the exact meaning of pragma:
no cover).

https://codereview.chromium.org/515093004/diff/1/appengine/chromium_cq_status...
File appengine/chromium_cq_status/model/record.py (right):

https://codereview.chromium.org/515093004/diff/1/appengine/chromium_cq_status...
appengine/chromium_cq_status/model/record.py:9: class Record(ndb.Model): #
pragma: no cover
Why no cover? Is it just one line, or the whole class?

[jam, 2014-08-28 23:13:28]

btw Sergey said he preferred I use a new app for my purposes, so I won't need
this anymore.

[alancutter (OOO until 2018), 2014-08-29 01:38:36]

If this isn't required by jam I'll put this change on hold until it actually
gets used.

https://codereview.chromium.org/515093004/diff/1/appengine/chromium_cq_status...
File appengine/chromium_cq_status/model/record.py (right):

https://codereview.chromium.org/515093004/diff/1/appengine/chromium_cq_status...
appengine/chromium_cq_status/model/record.py:9: class Record(ndb.Model): #
pragma: no cover
On 2014/08/28 21:14:15, Sergey Berezin wrote:
> Why no cover? Is it just one line, or the whole class?

Everything under appengine/ has "# pragma: no cover" because the coverage tool
run by test.py doesn't detect appengine test coverage correctly.
Without this pragma test.py will complain about no coverage despite there being
tests that run this code.

Ironically the no cover pragma is only required for apps that get tested by
test.py.