Code review comment for lp:~thumper/juju-core/refactor-uniter-tests

Reviewers: mp+198668_code.launchpad.net,

Message:
Please take a look.

Description:
Refactor uniter tests

We needed to have a better way to match the hooks that had been executed
by
the uniter in the tests. Instead of relying on log messages that the
hooks
wrote out, instead we have the uniter optionally call out to an
observer.

Part of this work also involved breaking up some of the larger methods
in the
Context and the Uniter methods. These broken up bits are used by the
code
that runs generic commands coming shortly.

A fundamental change is that now if a hook is missing, instead of
silently
passing, the context now returns a missingHookError.

https://code.launchpad.net/~thumper/juju-core/refactor-uniter-tests/+merge/198668

Requires:
https://code.launchpad.net/~thumper/juju-core/juju-run-listener/+merge/198662

(do not edit description out of merge proposal)

Please review this at https://codereview.appspot.com/41210043/

Affected files (+181, -109 lines):
   A [revision details]
   M worker/uniter/context.go
   M worker/uniter/context_test.go
   A worker/uniter/export_test.go
   M worker/uniter/uniter.go
   M worker/uniter/uniter_test.go