Test on multiple MongoDB versions, with and without timezone support.

.travis.yml

@@ -16,15 +16,26 @@ python:
   - "3.5"
   - "3.6"
 
+env:
+  - MONGODB_VERSION=3.4.7
+
+matrix:
+  include:
+    - python: "3.5"
+      env: NO_PYTZ=1
+    - python: "3.5"
+      env: MONGODB_VERSION=3.2.13
+
 before_install:
-  - wget http://fastdl.mongodb.org/linux/mongodb-linux-x86_64-3.4.7.tgz -O /tmp/mongodb.tgz
+  - wget http://fastdl.mongodb.org/linux/mongodb-linux-x86_64-${MONGODB_VERSION}.tgz -O /tmp/mongodb.tgz
   - tar -xvf /tmp/mongodb.tgz
   - mkdir /tmp/data
-  - ${PWD}/mongodb-linux-x86_64-3.4.7/bin/mongod --dbpath /tmp/data --bind_ip 127.0.0.1 --noauth &> /dev/null &
+  - ${PWD}/mongodb-linux-x86_64-${MONGODB_VERSION}/bin/mongod --dbpath /tmp/data --bind_ip 127.0.0.1 --noauth &> /dev/null &
 
 install:
-  - travis_retry pip install --upgrade setuptools pip pytest pytest-cov codecov 'setuptools_scm>=1.9' cffi
-  - pip install -e '.[development,logger]'
+  - 'travis_retry pip install --upgrade setuptools pip pytest pytest-cov codecov "setuptools_scm>=1.9" cffi'
+  - 'pip install -e ".[development,logger]"'
+  - '[[ -e $NO_PYTZ ]] && pip uninstall --quiet --yes pytz tzlocal'
 
 script:
     python setup.py test