Add a tox env to make dists and test them

.travis.yml

@@ -30,17 +30,20 @@ notifications:
 jobs:
   include:
 
-    - language: python
+    - &check
+      language: python
       env:
         - TOXENV=style
       os: linux
       python: "3.7"
 
-    - language: python
+    - <<: *check
       env:
         - TOXENV=type
-      os: linux
-      python: "3.7"
+
+    - <<: *check
+      env:
+        - TOXENV=packaging
 
     # Upload the package to `test.pypi.org` when there is a push to
     # `release/test` branch:

tox.ini

@@ -36,6 +36,20 @@ source =
     .tox/*/lib/python*/site-packages/tkfplaygroundpy
 # https://coverage.readthedocs.io/en/coverage-4.5.1/config.html#paths
 
+[testenv:packaging]
+commands_pre =
+    rm -rf dist
+    rm -rf src/tkfplaygroundpy.egg-info
+commands =
+    python setup.py sdist
+    python setup.py bdist_wheel
+commands_post =
+    sh -c "tar tf dist/tkfplaygroundpy-*.tar.gz | grep LICENSE"
+    sh -c "unzip -l dist/tkfplaygroundpy-*.whl | grep LICENSE"
+whitelist_externals =
+    rm
+    sh
+
 [testenv:style]
 deps =
     black == 19.3b0