Validate project metadata

Adds a step that builds and tests both deliverables using twine.

Change-Id: Ib1d867df19d56bb01dcb2fed9e785d04286764c4

.gitignore

@@ -2,6 +2,7 @@
 *.egg-info
 *.pyc
 *.retry
+.eggs
 .idea
 .mypy_cache
 .test

tox.ini

@@ -18,7 +18,9 @@ passenv =
   OS_STDERR_CAPTURE
   OS_STDOUT_CAPTURE
 usedevelop = True
-whitelist_externals = bash
+whitelist_externals =
+  bash
+  rm
 deps =
   -r{toxinidir}/requirements.txt
   -r{toxinidir}/test-requirements.txt
@@ -34,9 +36,14 @@ install_command = pip install {opts} {packages}
 deps =
   flake8
   mypy<0.790
+  twine>=3.3.0
 commands =
   flake8 {posargs}
   mypy --ignore-missing-imports zuulclient
+  # metadata validation
+  rm -rfv {toxinidir}/dist/
+  python setup.py sdist bdist_wheel
+  twine check --strict {toxinidir}/dist/*
 
 [testenv:cover]
 setenv =