enable coverage on Travis

- ensure pip is up to date
- enable pip caching
- run tests with Python 3.6
- publish coverage to codecov

.gitignore

@@ -9,6 +9,8 @@ MANIFEST
 
 .DS_Store
 .cache
+.coverage
+htmlcov
 
 repo2docker/s2i
 

.travis.yml

@@ -1,20 +1,25 @@
 language: python
 sudo: required
+cache: pip
 services:
 - docker
 python:
-- 3.4
+- 3.6
 install:
-# Make a wheel and install it to test to catch possible
-# issues with MANIFEST.in
-- pip install --no-cache-dir -r dev-requirements.txt
-- python setup.py bdist_wheel
-- pip install dist/*.whl
+  # Make a wheel and install it to test to catch possible
+  # issues with releases
+  - pip install --upgrade setuptools pip
+  - pip install -r dev-requirements.txt
+  - python setup.py bdist_wheel
+  - pip install dist/*.whl
 
 script:
   # cd into tests so CWD being repo2docker does not hide
   # possible issues with MANIFEST.in
-  - cd tests && pytest -s -v ${REPO_TYPE}
+  - cd tests && pytest --cov repo2docker -s -v ${REPO_TYPE}
+after_success:
+  - pip install codecov
+  - codecov
 
 jobs:
   include:

dev-requirements.txt

@@ -1,3 +1,4 @@
 pyyaml
 pytest
 wheel
+pytest-cov