Fix Travis build on OSX

As noticed in PR #42, Travis was not installing the different Python
versions correctly anymore.

Author: Ezibenroc

.travis.yml

@@ -14,50 +14,26 @@ matrix:
       dist: xenial
       sudo: required
       python: 3.7
-#    - os: linux
-#      dist: trusty
-#      sudo: required
-#      python: pypy
-# Travis does not support yet Python installation on OSX (see https://github.com/travis-ci/travis-ci/issues/2312).
-# We will therefore only test with the preinstalled Python 2.7
     - os: osx
       language: generic
-      env: PYTHON=2.7-dev
+      env: PYTHON=2.7.15
     - os: osx
       language: generic
-      env: PYTHON=3.5
+      env: PYTHON=3.5.6
     - os: osx
       language: generic
-      env: PYTHON=3.6
+      env: PYTHON=3.6.7
     - os: osx
       language: generic
-      env: PYTHON=3.7
+      env: PYTHON=3.7.1
 
 before_install: |
-  # These steps are taken from https://pythonhosted.org/CodeChat/.travis.yml.html
   if [ "$TRAVIS_OS_NAME" == "osx" ]; then
-    brew update
-    # Per the `pyenv homebrew recommendations <https://github.com/yyuu/pyenv/wiki#suggested-build-environment>`_.
-    brew install openssl readline
-    # See https://docs.travis-ci.com/user/osx-ci-environment/#A-note-on-upgrading-packages.
-    # I didn't do this above because it works and I'm lazy.
-    brew outdated pyenv || brew upgrade pyenv
-    # virtualenv doesn't work without pyenv knowledge. venv in Python 3.3
-    # doesn't provide Pip by default. So, use `pyenv-virtualenv <https://github.com/yyuu/pyenv-virtualenv/blob/master/README.md>`_.
-    brew install pyenv-virtualenv
-    pyenv install $PYTHON
-    # I would expect something like ``pyenv init; pyenv local $PYTHON`` or
-    # ``pyenv shell $PYTHON`` would work, but ``pyenv init`` doesn't seem to
-    # modify the Bash environment. ??? So, I hand-set the variables instead.
-    export PYENV_VERSION=$PYTHON
-    export PATH="/Users/travis/.pyenv/shims:${PATH}"
-    pyenv-virtualenv venv
-    source venv/bin/activate
-    # A manual check that the correct version of Python is running.
-    python --version
+    source .travis_osx.sh
   fi
 
 install:
+    - python --version
     - pip install hypothesis Cython wheel
 
 script:

.travis_osx.sh

@@ -0,0 +1,12 @@
+# These steps are taken from https://pythonhosted.org/CodeChat/.travis.yml.html
+brew update
+brew install openssl readline
+curl -L https://github.com/pyenv/pyenv-installer/raw/master/bin/pyenv-installer | bash
+export PATH="${HOME}/.pyenv/bin:${PATH}"
+eval "$(pyenv init -)"
+eval "$(pyenv virtualenv-init -)"
+pyenv install $PYTHON
+export PYENV_VERSION=$PYTHON
+export PATH="/Users/travis/.pyenv/shims:${PATH}"
+pyenv virtualenv venv
+pyenv activate venv