Check that all po/pot files are valid

Perform minimal checks on po and pot files so that no broken files can
get imported.

Add msgfmt to list of requirements in doc/source/setup.rst.

Change-Id: Ifa9fe2fc1ca9a41621ff3039c249700cdb1cd0ac
Related-Bug: #1299349
Co-Authored-By: Clark Boylan <clark.boylan@gmail.com>

doc/source/setup.rst

@@ -42,6 +42,7 @@ And that you have the following tools available on your system:
 - git_
 - setuptools_
 - pip_
+- msgfmt (part of the gettext package)
 
 **Reminder**: If you're successfully using a different platform, or a
 different version of the above, please document your configuration here!

tox.ini

@@ -10,11 +10,18 @@ setenv = VIRTUAL_ENV={envdir}
 deps = -r{toxinidir}/requirements.txt
        -r{toxinidir}/test-requirements.txt
 commands = python setup.py testr --slowest --testr-args='{posargs}'
+whitelist_externals = bash
 
 [testenv:pep8]
 envdir = {toxworkdir}/venv
 commands = 
   flake8 {posargs}
+  # Check that .po and .pot files are valid.
+  # NOTE(jaegerandi): We search for files ending with '.po' or '.pot'.
+  # The regex '.*\.pot?' does not work on OS X and we assume there are no
+  # files with more than one "t" that have to be ignored.
+  bash -c "find keystone -type f -regex '.*\.pot*' -print0| \
+           xargs -0 -n 1 msgfmt --check-format -o /dev/null"
 
 [tox:jenkins]
 downloadcache = ~/cache/pip