This role currently does
which tox || pip install --user tox
and then sets "tox_exectuable" iff it has installed tox into the
user's pip environment.
This isn't idempotent -- if you run ensure-tox again, it will again
run "which tox" and miss that it already installed tox in the private
pip environment. Instead, make it look for
"which {{ tox_executable }}" ... this way it will find the install it
just did if it runs again.
There seems to be no reason to only set "tox_exectuable" in the case
this role had to install tox. Make this *always* set tox_exectuable
so that you can run ensure-tox and then be sure tox_exectuable is
something sane.
The current testing assumes that tox is installed in the base image.
We are working to remove this assumption; remove this part of the
test.
Rework the testing to first clear out any existing tox, which is
present on most images but will have no effect on the -plain images.
Then test when we install fresh it goes into the user pip install
area, and then test if we explicitly set tox_exectuable it overrides.
Change-Id: I36cfb62f2a2e2b9c2bbe92b46ed0b8098a873732
b2d27969a9