Add a base cleaner suite to add cleanup methods

Add a base cleaner suite to add cleanup methods

Also made the LoggerSuite embed it, so most existing
tests get the magic.

https://code.launchpad.net/~thumper/juju-core/cleanup-suite/+merge/185199

(do not edit description out of merge proposal)

[thumper, 2013-09-12 05:05:17]

Please take a look.

[axw1, 2013-09-12 05:10:12]

On 2013/09/12 05:05:17, thumper wrote:
> Please take a look.

LGTM.

[wallyworld, 2013-09-12 05:11:13]

LGTM but I'd like some tests to ensure there's no cross contamination between
suite and test cleanup

[rog, 2013-09-12 07:09:41]

LGTM with a couple of minor suggestions.

Embedding this into LoggingSuite makes me
feel twitchy though. This a marriage entirely
of convenience - LoggingSuite previously
was about a single thing only, and now has
this functionality shoehorned in just because
lots of things use LoggingSuite.

I would be more inclined to embed it in some
of the "kitchen-sink" suites: JujuConnSuite;
or rename LoggingSuite to LoggingAndCleanupSuite
perhaps throughout.

I like the functionality in general though.

https://codereview.appspot.com/13633045/diff/1/testing/cleanup.go
File testing/cleanup.go (right):

https://codereview.appspot.com/13633045/diff/1/testing/cleanup.go#newcode14
testing/cleanup.go:14: testStack  []func()
One possibility is to use jc.Restorer instead of func() here, which perhaps
makes the purpose of the functions more clear.

It doesn't really make any difference, just a thought.

https://codereview.appspot.com/13633045/diff/1/testing/cleanup_test.go
File testing/cleanup_test.go (right):

https://codereview.appspot.com/13633045/diff/1/testing/cleanup_test.go#newcode10
testing/cleanup_test.go:10: testing.CleanupSuite
I'm not sure we need to embed this - you can just
declare it in each test, which I think will make the
tests a little clearer as it avoids shared state.